Sexually transmitted diseases

Definition

Sexually transmitted diseases (STDs) are viral and bacterial infections passed from one person to another through sexual contact.

Description

Adolescence is a time of opportunities and risk when many health behaviors are established. Although many of these behaviors are health-promoting, some are health-compromising, resulting in increasingly high rates of adolescent morbidity and mortality. For example, initiation of sexual intercourse and experimentation with alcohol and drugs are normative adolescent behaviors. However, these behaviors often result in negative health outcomes such as the acquisition of STDs. As a consequence of STDs, many adolescents experience serious health problems that often alter the course of their adult lives, including infertility, difficult pregnancy, genital and cervical cancer , neonatal transmission of infections, and AIDS (acquired immunodeficiency syndrome).

Examples of STDs with high prevalence among sexually-active adolescents include:

• Gonorrhea: Caused by the bacteria Neisseria gonorrhoeae, gonorrhea infects the reproductive tract of women, causing pelvic inflammatory disease (PID), a major cause of infertility. The bacteria are found in vaginal secretions and semen.
• Chlamydia: The bacteria that causes chlamydia, Chlamydia trachomatis, trigger inflammation of the reproductive tract, leading to PID in women and epididymitis (inflammation of the epididymis) in men.
• Syphilis: Treponema pallidum is the bacteria that causes syphilis. The course of syphilis is broken down into four distinct segments: primary syphilis, occurring within a few weeks or months of initial exposure; secondary syphilis, occurring generally between six weeks and six months of initial exposure; latent syphilis, an asymptomatic period which may stretch for years; and late syphilis, the most serious stage. If left untreated, syphilis can infect a number of organ systems and cause serious complications.
• Herpes simplex virus: Two different types of HSV (HSV-1 and HSV-2) cause lesions on the genitals, although HSV-2 is associated with the majority of cases. (HSV-1 is most commonly associated with oral lesions, or "cold sores.")
• Human papillomavirus (HPV): HPV causes condylomata acuminata, more commonly known as venereal warts or genital warts. The warts may affect any of the external and internal genital organs in men and women.
• Human immunodeficiency virus (HIV). HIV is the causative agent of acquired immune deficiency syndrome (AIDS), a potentially fatal condition in which the immune system fails and the individual becomes prone to frequent and unusual infections.

Transmission

The mode of transmission varies among the different sexually transmitted diseases. Some bacteria or virus are found in vaginal secretions or semen (e.g. HIV and gonorrhea), while others are shed from the skin of and around the genitals (e.g. HSV and HPV). Infection typically occurs during sexual intercourse or when the genitals come into close contact. Infection may also occur during oral sex, such as transmission of HSV from an oral lesion to the genitals or vice versa, or transmission of HIV from genital secretions through a cut in the mouth. STDs may be transmitted during nonconsensual sex acts such as rape or molestation.

The transmission of many STDs is more efficient from men to women than from women to men. For example, with just one unprotected sexual encounter with an infected partner, a woman is twice as likely as a man to acquire gonorrhea or chlamydia. In addition, different STDs have different rates of transmissibility. For example, with one exposure of unprotected sexual intercourse, a woman has a 1 percent chance of acquiring HIV, a 30 percent chance of acquiring herpes, and 50 percent chance of contracting gonorrhea if her partner is infected.

Demographics

STDs among sexually experienced adolescents occur at alarmingly high rates. One-fourth of the estimated 12 million new cases reported annually occur among adolescents between 15 and 19 years of age. Moreover, since many STDs are asymptomatic, they are often undiagnosed and untreated, thus increasing their potential for proliferation among adolescents.

Gonorrhea and chlamydia, the most prevalent bacterial STDs, disproportionately affect adolescents. The rates of gonorrhea in adolescents ages 15 to 19 years declined between 1990 and 2004, but in the early 2000s they continue to be higher than rates for any five-year age group between 20 and 44 years, particularly among women and African Americans.

Numerous prevalence studies for chlamydia have shown rates to be highest among adolescents and young adults under 25 years of age, many of whom are minorities. Rates of chlamydia reported by gender indicate that women, overall, have higher rates than men due in large part to increased efforts in screening women for asymptomatic chlamydial infections. The low rates of chlamydia for men suggest that the sexual partners of women diagnosed with chlamydia are not being diagnosed or treated. Chlamydia has been detected in more than 10 percent of sexually experienced women during screening.

While rates of syphilis declined between 1990 and 2004, the disease continues to be an important cause of sexually transmitted infection. The rate of syphilis infection among adolescents ages 15 to 19 is 1.3 per 100,000 population for males and 2.2 per 100,000 population for females. For comparison, the syphilis rates among males 20 to 24 is 5.5 per 100,000, and among females of the same age, 3.3 per 100,000.

HSV and HPS occur at alarming rates among sexually experienced adolescents. Studies indicate that one in six Americans is infected with HSV-2, reflecting a ninefold increase between 1975 and 2005. Prevalence of HSV-2 in adolescents and young adults varies by the demographic and behavioral characteristics of the populations studied as well as the diagnostic methods used. As of the early 2000s approximately 4 percent of Caucasians and 17 percent of African Americans are infected with HSV-2 by the end of their teenage years. One study of young pregnant women of low income status found an HSV-2 infection rate of 11 percent in women 15 to 19 years of age and 22 percent in women 25 to 29 years of age.

In 2002, there were 4,785 reported cases of AIDS among teenagers between the ages of 13 and 19, more than double the 1994 figures. Most adolescents with AIDS were infected as a result of high risk sexual and substance use behaviors. Among adolescents ages 13 to 19 years infected with HIV, 49 percent are male and 51 percent are female. Studies also indicate that African-American and Latino teens are overrepresented among persons with AIDS relative to their proportion in the population. Although these epidemiological statistics on AIDS in the United States provide a descriptive overview of the prevalence and patterns of HIV exposure in adolescents, the extent of asymptomatic HIV infection remains largely unknown.

Causes and symptoms

The chance for adolescents of getting and transmitting STDs is affected by complex interrelationships between key factors (sociodemographic, biologic, psychosocial, and behavioral). For example, many STD-related risk markers (e.g. age, gender, race/ethnicity) correlate with more fundamental determinants of risk status (e.g., access to health care, living in communities with high prevalence of STDs) to influence adolescents' risk for STDs.

Developmental factors such as pubertal timing, self-esteem , and peer affiliation may also increase their risk of exposure to STDs. An assessment of these interrelationships is critical to preventing and controlling STDs in adolescents. Moreover, since behavior is the common means by which STDs occur, an important first step in fighting STDs is to understand the prevalence and patterns of risk behaviors as well as the psychosocial context in which these behaviors occur.

Behavioral factors

Although biologic factors play an important role in the transmission of STDs, it is also the health-risking behaviors of adolescents that place them at increased risk for exposure to STDs. Behavioral risk factors include the age of sexual activity, number of sexual partners, use of contraceptives, and use of alcohol and drugs.

SEXUAL ACTIVITY Early initiation of sexual intercourse has been associated with high-risk sexual activities, including ineffective use of contraceptives, multiple sex partners over a short period of time, high-risk sex partners, and acquisition of STDs and their consequences of cervical cancer and dysplasia. The average age of first sexual intercourse is between 16 and 17 years for adolescent men and between the age of 17 and 18 years for adolescent women, and has been found to be as young as age 12 in some high-risk populations. Research on adolescents' decision to initiate sexual intercourse indicates an interaction between biological and social factors. However, much remains unknown about the interactions between hormones, behavior, and social factors.

The Youth Risk Behavior Surveillance System (YRBSS), a self-reported survey of a national representative sample of high school students in grades nine to 12, indicated that in 2003, 46.7 percent of the students reported having had sex. By grade level, the rates were 32.8 percent for ninth grade, 44.1 percent for tenth grade, 53.2 percent for eleventh grade, and 61.6 percent for twelfth grade. Approximately 7.4 percent of students reported having sex for the first time before age 13. Prevalence rates of sexual experience differed by race/ethnicity and gender. African-American students were significantly more likely (73.8% of males and 60.9% of females) than Caucasian (40.5% of males and 43.0% of females) and Hispanic (56.8% of males and 46.4% of females) students to have engaged in sexual intercourse. Moreover, data from the National Survey of Family Growth (NSFG), a large-scale national survey of women ages 15 to 44 years, reveal that family income is associated with adolescents' protection against HIV and many other STDs; adolescents from poor and low-income families are more likely to report an earlier age of sexual experience than their counterparts from higher income families.

In addition to early sexual activity, many adolescents have multiple sex partners within a short period of time in a pattern of serial monogamy which also increases their risk of acquiring STD for two important reasons: it increases the likelihood of being exposed to a sexually transmitted pathogen, and it may reflect poor choices of sexual partners. Among the sexually experienced high school students responding to the YRBSS, 14.4 percent reported having four or more sex partners. Multiple sex partners were noted more frequently among African-American students (41.7% of males and 16.3% of females), compared to Hispanic (20.5% of males and 11.2% of females) and Caucasian (11.5% of males and 10.1% of females) students.

Involuntary sexual intercourse such as rape and sexual abuse may occur more commonly among adolescents, especially younger adolescent women, and often pose a potential risk for acquisition of STDs. A study on the effects of child abuse (i.e., incest, extra-familial sexual abuse, and physical abuse) on adolescent males showed a strong association between abuse and a number of risk-taking behaviors, such as forcing female sexual partners into having sexual intercourse and drinking alcohol prior to sexual intercourse. Moreover, when sexual intercourse is intermittent, as it is with most sexually experienced adolescents, the adolescents are less likely to take proper measures to safeguard against STDs.

CONTRACEPTIVE USE Sexually experienced adolescents are also at risk for STDs because of their patterns of contraceptive use, especially their use of barrier-method contraceptives. Some data indicate that adolescents do not use effective methods to reduce their risk of STDs or unintended pregnancies. Sexual abstinence is the only sure method of eliminating risk for STDs. When used consistently and correctly, however, condoms offer the best protection against acquisition of STDs, including HIV. Even when condoms are used improperly they reduce the risk of acquiring infections by 50 percent.

The overall reported use of contraceptives, particularly condoms, has increased among adolescents between 1994 and 2004. Data from the 2003 YRBSS reveal that 63.0 percent of the students who reported sexual activity in the three months prior to the survey also reported using condoms during their last sexual encounter; this behavior was more common among males of virtually all ages and racial/ethnic groups. In contrast, 20.6 percent of adolescent women ages 15 to 19 years reported use of birth control pills. It appears that while the use of oral contraceptives provides some protection against the development of gonococcal and nongonococcal forms of PID, it may increase the risk of chlamydial endocervical infections, and provides no protection against most STDs.

Differences in the types and patterns of contraceptive use by race/ethnicity, age, and socioeconomic status have also been noted. Also, adolescent women of higher income are more likely than young women of lower income to use oral contraceptives. These factors are related to access and use of medical services for reproductive health care. Thus, providing all sexually experienced adolescents with reproductive health counseling and education about the importance of consistently and correctly using barrier-method contraceptives such as condoms may play a crucial role in reducing their risk of acquiring and transmitting STDs.

ALCOHOL AND OTHER DRUG USE Use of alcohol and other drugs is prevalent among adolescents and thus poses a significant threat to their health. About 40 percent of high school youth responding to the YRBSS have used marijuana at least once with 22.4 percent of these students reporting use of this substance within 30 days before the survey. Cocaine was used at least once by 8.7 percent of the students and by 4.1 percent within 30 days of the survey. The substance of choice, however, is alcohol: 74.9 percent of students had at least one drink at some point in time and nearly half (44.9%) consumed alcohol in the 30 days prior to the survey. Among the current alcohol users, 28.3 percent had five or more drinks on at least one occasion, suggesting that a sizeable proportion of the students are periodic heavy drinkers. Grade, age, and gender differences were noted for lifetime and current use of alcohol and other illicit substances. In general, students in higher grade levels (grades 11 and 12) and males were more likely to use all substances. Racial/ethnic differences in use of substances were also found. Heavy use of alcohol was most prevalent among Caucasian and Hispanic males and females, while marijuana use was most common among African-American and Hispanic males.

Although these data strongly suggest that adolescents are at increased risk for social and physical morbidities, and even premature mortality because of their use of alcohol and other illicit substances, they underrepresent the actual prevalence of substance use among all adolescents. Teens who have dropped out or who are repeatedly absent from school and those who are homeless or otherwise disenfranchised are not represented by the reported data; many of these teens are potentially at higher risk for STDs because of their substance use behavior.

Substance use prior to sexual intercourse is likely to be related to a number of risk-taking behaviors: sexual intercourse with a casual acquaintance, lack of communication about use of condoms or previous sexual experiences, and no use of condoms. This association remained significant regardless of demographic factors, sexual experience, and dispositional factors such as adventure and thrill seeking. It appears that early intervention to prevent the use and abuse of alcohol and other substances may significantly decrease their risk of acquiring STDs.

Psychosocial factors

One study of college students examined the relationship between sexual behavior, substance use, and specific constructs from social cognitive theory (i.e., perceptions of self-efficacy, vulnerability to HIV risk, social norms, negative outcome expectancies of condoms, and knowledge of HIV risk and prevention). The results indicate that although young men expected more negative outcomes of condom use and were more likely to have sexual intercourse under the influence of alcohol and other drugs, young women reported perceptions of higher self-efficacy to practice safer sex. The study further revealed that perceptions of higher self-efficacy to engage in safer sexual behaviors, perceptions of fewer negative outcomes of condom use, and less frequent alcohol and drug use with sexual intercourse were the best predictors of safer sexual behaviors.

Evaluating STD risk

The information, motivation, and behavioral skills (IMB) model is one method of evaluating risk for STDs. This model posits that information, motivation, and behavior are the primary determinants of AIDS-related preventive behavior. Specifically, the model asserts that information regarding the transmission of HIV and information concerning specific methods of preventing HIV (e.g., condom use, decreasing the number of partners) are necessary prerequisites of reducing risk behaviors.

Motivation to change risk behaviors is another determinant of prevention and affects whether a person acts on his or her knowledge of the transmission and prevention of HIV. The IMB contends that motivation to engage in prevention behaviors is a function of one's attitudes toward the behavior and of subjective norms regarding prevention behaviors. Other critical factors which are hypothesized to influence motivation to engage in prevention behaviors are perceived vulnerability to acquiring HIV, perceived costs and benefits of engaging in prevention behaviors, intention to engage in prevention behaviors regarding HIV, as well as characteristics of the sex partner and/or the sexual relationship (e.g. primary vs. secondary partner).

Behavioral skills for engaging in specific prevention behaviors are a third determinant of prevention; it affects whether a knowledgeable, highly motivated person will be able to change his or her behavior to prevent HIV. Important skills required to engage in prevention behaviors include the ability to effectively communicate with one's sex partner about safer sex, refusal to engage in unsafe sexual practices, proper use of barrier-method contraceptives, and the ability to exit a situation when prevention behaviors are not possible. In addition, individuals who are able to practice prevention skills are presumed to have a strong belief in their ability to practice these prevention behavioral skills. Overall, the IMB asserts that information and motivation trigger behavioral skills to affect the initiation and maintenance of HIV prevention behaviors.

Symptoms of common STDs

The symptoms of some STDs may seriously affect an infected individual's quality of life or eventually become fatal, while others are so mild as to go undetected. The symptoms of some of the more prevalent STDs include:

• Gonorrhea: The most common symptoms among infected adolescent girls are vaginal discharge, bleeding between menstrual cycles, and painful urination. Among adolescent boys, common symptoms are burning or painful urination and pus-like discharge from the penis. Many infections, however, remain asymptomatic in both females (32%) and males (2%). Symptoms are similar among young children who have contracted gonorrhea from a sexual abuser.
• Chlamydia: Symptoms of chlamydia are similar to those of gonorrhea and sometimes difficult to differentiate clinically. Chlamydial infections are more likely to be asymptomatic than gonorrheal infections and thus are of longer duration on average.
• Syphilis: In primarily syphilis, the characteristic symptom is the appearance of a chancre (painless ulcer) at the site of initial exposure (e.g. external genitalia, lips, tongue, nipples, or fingers). In some cases, the infected individual will experience swollen lymph glands. In secondary syphilis, the infection becomes systemic and the individual experiences symptoms such as fever , headache , sore throat , rash, and swollen glands. During latent syphilis, symptoms go unnoticed. During the late stage of syphilis, the infection has spread to organ systems and may cause blindness, signs of damage to the nervous system and heart, and skin lesions.
• Herpes simplex virus: The symptoms of genital herpes include burning and itching of the genital area, blisters or sores on the genitals, discharge from the vagina or penis, and/or flu-like symptoms such as headache and fever.
• Human papillomavirus (HPV): The warty growths of HPV can appear on the external or internal reproductive organs of males and females but are commonly found on the labia minora and the opening to the vagina in females and the penis in males. They may be small and few or combine to form larger growths.
• Human immunodeficiency virus (HIV): Some persons who are newly infected with HIV have rash, fever, enlarged lymph nodes, and a flu-like illness sometimes called HIV seroconversion syndrome. This initial syndrome passes without intervention, and later symptoms, when T-cells become depleted, include weight loss, chronic cough , fever, fatigue, chronic diarrhea , swollen glands, white spots on the tongue and inside of the mouth, and dark blotches on the skin or in the mouth.

When to call the doctor

If a child or adolescent develops any of the symptoms of STDs, he or she should be evaluated for possible infection. Routine pelvic exams are recommended for all sexually active females and all females over the age of 18.

Diagnosis

A history of sexual activity is collected from all individuals at increased risk of contracting an STD, including adolescents who admit to being sexually active or who are pregnant or have undergone therapeutic abortion, adolescents or children with symptoms indicative of infection with an STD, and adolescents or children suspected of being victims of sexual abuse or rape. The healthcare provider will take a complete medical history and perform a thorough physical examination. Depending on the STD in question, additional tests may be performed such as blood work, Papanicolaou (pap) smear, rectal swabs, or biopsy.

Treatment

The treatment of sexually transmitted diseases varies according to the diagnosed infection. Gonorrhea, chlamydia, and syphilis are curable in most cases with antibiotics , although antibiotic-resistant strains do exist. As viruses, HSV, HPV, and HIV are treatable but not curable. The frequency and duration of HSV lesions can be reduced with antiviral therapy, including acyclovir (Zovirax), famciclovir (Famvir), and valacyclovir (Valtrex). Common methods to reduce genital warts include application of a topical cream called imiquimod (Aldara), cryotherapy (freezing of the wart), elecrosurgery (applying an electrical current to the wart), and surgical removal. The course of HIV infection can be slowed with a number of different kinds of drugs, including reverse transcriptase inhibitors, protease inhibitors, nonnucleoside reverse transcriptase inhibitors, and fusion inhibitors.

Alternative treatment

A number of different alternative therapies may be pursued to treat STDs, such as the use of herbs, homeopathy, acupuncture, and nutritional supplements, although minimal research has been done to establish their efficacy.

Nutritional concerns

In some cases, supplementation with specific nutrients may enhance immunity and minimize outbreaks. Examples are vitamin C (to boost the immune system), zinc (to reduce the frequency of HSV outbreaks), aloe (a possible antiviral), lemon balm (to speed healing), and licorice (with anti-inflammatory and antiviral effects).

Prognosis

Most STDs have excellent prognoses and respond well to treatment. While HSV and HPS are not curable, outbreaks can be managed and infection generally has little effect on quality of life. HIV, however, is a potentially fatal disease which can be treated but not cured.

Prevention

The prevalence data on STDs, HIV, and AIDS in adolescents indicate that younger women, gay and bisexual teens, and poor, urban and racial/ethnic minority young people have higher rates of STDs and HIV relative to their peers. Primary prevention of initial STD infections through prevention and risk reduction programs are essential for stemming the tide of these sexually acquired diseases. Moreover, secondary prevention through screening at risk adolescents for asymptomatic STD infections and effectively treating the index case and his or her sexual contact(s) are the most effective means of eliminating long-term medical and psychosocial consequences from STDs.

Prevention of high risk sexual, contraceptive, and substance use behaviors through cognitive-behavioral skills training and prevention and risk reduction counseling programs is a key strategy for decreasing the high incidence of STDs in adolescents. Prevention and risk reduction strategies should be developed and implemented in settings in which most adolescents can be reached, including schools or community-based programs in which there are multiple opportunities to intervene with adolescents or clinical settings where one-to-one risk reduction counseling can occur and actual risk can be assessed.

Cognitive-behavioral skills building interventions

In order to prevent new STD infections, adolescents must not only be informed about the risk and prevention of STDs, they must also have skills to resist peer pressure , negotiate the use of condoms, and project the future consequences of their behaviors. In addition, prevention of STDs in adolescents requires that they have the necessary means, resources, and social support to develop self-regulative skills and self-efficacy to effectively reduce their risk of disease transmission. Such cognitive-behavioral skills building programs have been shown to be effective in developing skills, delaying the onset of sexual activity, and changing high risk behaviors associated with pregnancy, STDs, and HIV infection. Moreover, cognitive-behavioral skills building programs should be immediate, sustained, and cost-effective. Specifically, these programs should be designed to increase knowledge about the prevention and transmission of STDs and their consequences; formulate realistic attitudes and perceptions about personal susceptibility to acquiring infections; enhance self-efficacy and self-motivation; monitor and regulate STD-related risk behaviors; address the role of social peer norms; and develop appropriate decision-making, problem-solving, and communication skills .

Prevention and risk reduction counseling

Counseling strategies to prevent and reduce the risk of STDs should be conducted in a confidential and nonjudgmental manner that is both developmental and culturally appropriate for the adolescent. Counseling should focus on a number of key elements such as maintenance and support of healthy sexual behaviors (e.g. delaying initiation of sexual intercourse, limiting the number of sexual partners), use of barrier-method contraceptives (e.g. condoms, diaphragms, spermicide), routine medical care and advice (e.g. seeking medical care if the adolescent has participated in high-risk behavior), compliance with treatment recommendations (e.g. taking all medications as directed), and encouraging sex partners to seek medical care. Adolescents should also be informed about the myths and misconceptions of acquiring STDs. Moreover, adolescents should receive anticipatory guidance to assist them in defining appropriate options and alternatives to engaging in high-risk behaviors.

Parental concerns

Parents should be encouraged to talk to their children about sexually transmitted diseases and the risks of sexual activity. By asking preteens or teenagers questions about what they knows about STDs or by using cues from television shows or newspaper articles, parents can help make their children more comfortable talking about sex and the risks of infection, thereby opening the lines of communication. It is important that adolescents be provided accurate information, even if they already have some knowledge on the topic. Research has shown teens are not more likely to have sex if they are informed about safe sex practices, but they are more likely to practice safer sex.

KEY TERMS

Opportunistic infection —An infection that is normally mild in a healthy individual, but which takes advantage of an ill person's weakened immune system to move into the body, grow, spread, and cause serious illness.

Pap test —A screening test for precancerous and cancerous cells on the cervix. This simple test is done during a routine pelvic exam and involves scraping cells from the cervix. These cells are then stained and examined under a microscope. Also known as the Papanicolaou test.

Resources

BOOKS

Hammerschlag, Margaret R., Sarah A. Rawstron, and Kenneth Bromberg. "Sexually Transmitted Diseases." In Krugman's Infectious Diseases of Children, 11th ed. Edited by Anne A. Gershon, Peter J. Hotez, and Samuel L. Katz. New York: Mosby, 2004.

Jenkins, Renee R. "Sexually Transmitted Diseases." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman, Robert M. Kliegman, and Hal B. Jenson. Philadelphia: Saunders, 2004.

MacDonald, Noni E., and David M. Patrick. "Sexually Transmitted Disease Syndromes." In Principles and Practice of Pediatric Infectious Diseases, 2nd ed. Edited by Sarah S. Long. New York: Churchill Livingstone, 2003.

PERIODICALS

Department of Health and Human Services, Centers for Disease Control and Prevention. "Youth Risk Behavior Surveillance: United States, 2003." Morbidity and Mortality Weekly Report 53, no. SS-2 (May 21, 2004): 12–20.

ORGANIZATIONS

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. Web site: <www.cdc.gov>.

WEB SITES

Divisions of HIV/AIDS Prevention, National Center for HIV, STD, and TB Prevention. "HIV/AIDS Surveillance in Adolescents." Centers for Disease Control and Prevention (CDC), August 25, 2004. Available online at <www.cdc.gov/hiv/graphics/adolesnt.htm> (accessed January 17, 2005).

Divisions of STD Prevention, National Center for HIV, STD, and TB Prevention. "Sexually Transmitted Disease Surveillance 2002 Supplement: Syphilis Surveillance Report." Centers for Disease Control and Prevention (CDC), January 2004. Available online at <www.cdc.gov/std/Syphilis2002/SyphSurvSupp2002.pdf> (accessed January 17, 2005).

Gearhart, Peter A., et al. "Human Papillomavirus." eMedicine, December 13,, 2004. Available online at <www.emedicine.com/med/topic1037.htm> (accessed January 17, 2005).

Lamprecht, Catherine. "Talking to Your Child about STDs." Nemours Foundation, May 2001. Available online at <http://kidshealth.org/parent/positive/talk/talk_child_stds.html> (accessed January 17, 2005).

Stephanie Dionne Sherk

Sexually Transmitted Diseases

The world continues to live with the ironic realization that the most intimate form of human relations, that of sexual interactions, carries the threat of serious disease. Sexually transmitted diseases (STDs), once known as venereal diseases, have menaced humankind since the dawn of recorded history. There are references to STDs in Egyptian papyri dating to 1550 BCE, and according to biblical scholars, there are similar references in the Old Testament (Holmes et al. 1999). STDs operate at the intersection of individual human behaviors, collective sociodemographic trends, and specific disease pathogens. They are diseases caused by bacteria, viruses, protozoa, fungi, and ectoparasites. In society and within the lives of families and individuals, STDs continue to inflict considerable suffering, trauma, serious medical conditions, and medical expense. They can often stigmatize the infectee; they also can cause death. Despite powerful treatments including newer antibiotics, better diagnostic tools using advanced technologies, extensive prevention programs, and increased international awareness, STDs remain among the most common reported diseases.

Tragically, they have a global reach that in many countries dwarfs the burden in the United States. The World Health Organization estimated that in 1999, among women and men aged fifteen to forty-nine years, there were approximately 340 million new cases of the most common, nonviral, sexually transmitted diseases that occurred throughout the world. They were syphilis (12 million), gonorrhea (62 million), chlamydia (92 million), and trichomoniasis (174 million). STDs most commonly affect people when they are between the ages of fifteen and forty-four, during their peak years of economic production (Ober and Piot 1993). This is of particular concern to developing countries.

For these four STDs and several others (there are more than twenty-five pathogens that can be transmitted by sexual intercourse), their spread in a population is a function of the average number of new cases caused by an infected person (often referred to as the force of infectivity). This number is the product of the efficiency of transmission of the STD, the average duration of infectiousness of the STD, and the mean number of different sexual partners per unit time (Anderson and May 1991). The use of numerical methods using this kind of methodology has allowed population- and country-specific estimates for incidence and prevalence of the most common STDs.

The three most common and threatening sequelae (i.e., after-effects) of STDs to infected individuals are impaired fertility for women, adverse pregnancy outcomes, and increased susceptibility to the human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS). STDs cause acute illnesses, long-term suffering and disability, and infertility. Related psychological and medical consequences have an enormous global economic impact.

Since World War II, advances in epidemiology, disease surveillance, behavioral and social sciences, demographics, and medical science have greatly contributed to a better understanding of how STDs occur, are sustained, and shift into new populations in society; how they interact with each other; how several STDs can be successfully treated and cured (although many still cannot); and, importantly, how they and their most common sequelae can often be prevented. Despite these modern advances, STDs continue to imperil society, families and other loved ones, and individuals.

Although difficult to estimate (approximately 12 million infections from STDs occur annually in the United States), two-thirds of the infections from STDs occur among people less than twenty-five years of age (Noegel et al. 1993). Women and the poor suffer disproportionately, and it is estimated that one of every four people in the United States will have an STD in his or her lifetime. STDs are most commonly transmitted either from males to their female sex partners or from females to their male sex partners. Male to male transmission occurs often with some STDs, whereas female to female transmission occurs infrequently with nearly all STDs. Of the more than twenty-five known pathogens that are classified as causing STDs in humans, only the most important will be addressed here.

Bacterial STDs

Though readily curable, these STDs (sometimes referred to as Sexually Transmitted Infections, or STIs) account for considerable morbidity, ranking among the most frequently reported communicable diseases. Chlamydia and gonorrhea pose threats to the reproductive health of women and are readily transmitted between sex partners. These and many other bacterial STDs influence adverse pregnancy outcomes, either during fetal development or during birth. No effective vaccines exist for these diseases.

Chlamydia. This disease is thought to be the most common of all STDs in the United States. Between 20 percent and 40 percent of sexually active women have been exposed; they have chlamydial antibodies. Since the 1970s, the pathogenesis (i.e., production and development) of and threats to reproductive health from chlamydia have become better understood; it has emerged as an STD with major consequences. It has been estimated that more than $2 billion is spent each year in the United States on treatment of chlamydia and its complications (Noegel et al. 1993). The most common clinical manifestations of chlamydial infections in women are salpingitis and mucccopurulent cervicitis, with the endocervix being the most common site of infection. Chlamydia is a particularly insidious STD because women with active infections usually have minimal or no symptoms. Most women are unlikely to be treated unless: (1) they undergo a screening test (a rapid, inexpensive diagnostic test has only recently become widely available in the United States, but is still unavailable in many parts of the world) that specifically cultures the pathogen; or (2) their male sex partner develops a symptomatic infection and the woman is informed. Seven-day oral antibiotic regimens of either doxycycline or azithromycin are effective treatment of chlamydia in men and women. A single dose azithromycin regimen is equally effective, and, though more expensive, is now available.

Gonorrhea. This disease is the second most commonly reported STD in the United States (approximately 350,000 cases per year are reported [approximately 260 cases per 100,000 U.S. population for men and women combined; many more are thought to occur]). The highest age-specific rates are for women ages fifteen to nineteen and for men ages twenty to twenty-four (Centers for Disease Control and Prevention 2000). For women, gonococcal infection occurs primarily in the cervix, although the pharynx, rectum, and urethra can also be infected. Approximately 40 percent to 60 percent of women with gonorrhea have symptoms, sometimes painful. Gonorrhea, which is less "silent" than chlamydia, can cause a purulent vaginal discharge, dysuria, and frequent urination. Cervical gonococcal infection is usually diagnosed via an endocervical culture. Most infected men have painful symptoms, usually pain and discharge upon urination, which cause them to seek treatment. Several antibiotic regimens (e.g., a single oral dose of cefixime) are safe and effective for most cases (Centers for Disease Control and Prevention 1993). Ominously, about one-third of all gonococcal isolates now manifest some degree of resistance to this conventional therapy, thus causing reliance on more expensive antibiotics and creating concern that some emerging gonococcal strains may soon be resistant to all known forms of antibiotics.

Comparison of chlamydia and gonorrhea. About 25 percent to 40 percent of women with gonorrhea also have a concurrent chlamydial infection. Yet the percentage of women with gonorrhea who also have a concurrent chlamydial infection varies dramatically by subpopulation (Holmes et al. 1999). (Since 1975, trends in reported U.S. gonorrhea rates have steadily declined.) Chlamydia is thought to be homogeneously distributed in the population, although focused in those who are younger, yet sexually active, whereas gonorrhea disproportionately affects minority populations. (In 2000, the ratio of U.S. gonorrhea cases reported in African Americans to whites was five to one; in Hispanics to whites, one to two; [Centers for Disease Control and Prevention 2000]). However, these differences should be viewed cautiously. Research analyzing population-based survey data suggests that the real differences may be less striking (Anderson, McCormick, and Fichtner 1994). Case reporting from publicly funded medical facilities tends to be more complete than that from private facilities, and minority populations disproportionately use publicly funded facilities. All states legally require the medical reporting of most STDs, but inconsistent adherence as well as frequent self-treatment of STDs prevent more accurate estimates of the incidence of STDs in the United States and thereby inhibit a better understanding of their respective epidemiologies.

Pelvic inflammatory disease (PID). PID broadly defines an array of inflammatory conditions, the most common of which are endometritis and salpingitis, which affect the upper reproductive tract of women. Symptoms are often pain with concurrent fever. (There are approximately 2.5 million symptomatic outpatient visits to medical facilities for PID annually in the United States. Nearly 300,000 women are hospitalized annually, and more than 100,000 associated surgical procedures need to be performed [Centers for Disease Control and Prevention 2000]). Most cases of PID are caused, directly or indirectly, by gonococcal and chlamydial infections. PID is frequently episodic, with initial acute episodes being directly caused by untreated or repeat infections of gonorrhea or chlamydia. Subsequent episodes can be caused by nonsexually transmitted pathogens or intrauterine contraceptive devices. Infertility caused by occlusion of the fallopian tubes, chronic pelvic pain, and ectopic pregnancy is the most frequent and serious complication of repeat episodes of PID. A diagnosis of PID is often difficult because there is a wide range of signs and symptoms—or none at all. Women and health care providers should be suspicious of symptoms, especially if there is a history numerous sex partners. A variety of antibiotic therapies (e.g., cefoxitin plus doxycycline) are available for PID; most require aggressive, extended regimens, usually up to fourteen days, for maximum effectiveness.

Syphilis. This disease has been central to the development of the practice of medicine and was the basis for venereology, an early medical subspecialty. Epidemic and a scourge in Europe in the fifteenth century, its symptoms, natural history, and transmission dynamics have fascinated students of medicine for years; its malevolence has caused great personal suffering; and it continues to be a prevention and treatment challenge. In the late 1970s and early 1980s, syphilis in the United States was at moderate levels and was primarily a disease that occurred in homosexual men (Fichtner et al. 1983). However, in the late 1980s, there was a surge in the reported incidence of syphilis in the United States, peaking at about 135,000 cases in 1990. About 50,000 of those cases in 1990, up from approximately 27,000 cases in 1985, represented occurrences of syphilis in primary or secondary stages, when the disease is infectious (i.e., transmissible). From 1990 to 2000, the rate of infectious syphilis declined by 89.2 percent. In 2000, only 5,979 cases were reported in the United States, the lowest since reporting began in 1941 (Centers for Disease Control and Prevention 2000).

About one-third of persons exposed to infectious syphilis acquire it. Within twenty-one days, primary, relatively painless lesions (ulcers or chancres) usually appear. Often these lesions disappear (after ten to ninety days) if the disease is untreated. The disease then reemerges in a secondary stage characterized by more disseminated symptoms, usually malaise, sore throat, and adenopathy (sore lymph glands). During this secondary stage, the classic rash of syphilis appears, often visible on the palms of the hands and soles of the feet. If the disease is still untreated in the secondary stage, a latent period of variable duration is entered by the patient. Subsequently, approximately 15 to 40 percent of the untreated patients develop tertiary syphilis, and small numbers of those (approximately 5–20%) develop serious neurological and/or cardiovascular manifestations that can become life-threatening (Holmes et al. 1999). These late manifestations are rarely seen in the United States.

Untreated pregnant women who are infected with syphilis have a 50 percent change of transmitting the disease to their newborns. About half of these women deliver a preterm baby or a still birth. Throughout the world, this is the most serious direct outcome of syphilis. (The rise of syphilis in U.S. women in the late 1980s, cresting in 1990, increased the concern for preventing cases of congenital syphilis. A peak in reported cases [approximately 4,400] of congenital syphilis occurred in 1991. [Centers for Disease Control and Prevention 2000]).

Syphilis is readily diagnosed by serologic (blood) testing; screening tests are inexpensive and routinely performed in a variety of settings. In the United States, premarital screening is required in nearly all states, a reminder of the history of the disease. One intramuscular injection of benzathine penicillin is the usual, effective treatment for syphilis during its early stages.

Viral STDs

These diseases are incurable, but during the 1980s and 1990s, many technological advances led to improved diagnostic tools, thus enabling a clearer understanding of the distribution of these diseases in the world. For some of the viral STDs, therapies to minimize symptoms exist. Hepatitis B virus (HBV), which is often but not always sexually transmitted, is the only STD for which an effective vaccine has been developed and is readily available.

Herpes simplex virus (HSV) infection. Herpes (from the Greek, to creep) is another STD with a long history. There are two major types of HSV: HSV-1 and HSV-2. Genital herpes, the clinical condition, is most often caused by HSV-2, and caused much less frequently by HSV-1. A prior history of HSV-1 appears to increase the risk of acquiring HSV-2. Herodotus, a Roman physician, described cold sores (from HSV-1) in the second century, and genital herpes was first described by John Astruc, a French physician in the eighteenth century, Shortly thereafter, other physicians noted that genital herpes often afflicted a patient shortly after the onset of syphilis or gonorrhea. Genital herpes results in painful ulcers that last about ten to fourteen days; both men and women can be affected. These ulcers can be treated by antiviral agents to ease discomfort and shorten periods of symptoms, but the infection persists in the body and symptoms are likely to reoccur. HSV-2 is most frequently transmitted by viral shedding from ulcers during sex, but transmission can occur even when no genital ulcer is evident. It can be acquired by the infant from its mother during child birth.

Both HSV-1 (much lower worldwide prevalence) and HSV-2 are widespread throughout the world. Surveys conducted in the United States have led to the approximation that about 20 percent of persons fifteen to seventy-four years of age have antibodies to HSV-2. From a survey conducted in the United States in the early 1990s, it was approximated that 31 million persons living in the United States are infected, as determined by the prevalence of serum antibodies, and it is estimated that approximately 20 to 25 percent of persons living in the United States will contract diagnosable (via symptoms) genital herpes sometime in their lives. Numerous studies have associated the presence of HSV-2 with the lifetime number of sex partners, history of other STDs, and age at first sex (i.e., sexual debut).

Several studies have linked HSV-2 with genital cancers in women (Holmes et al. 1999), and this is an area of intense epidemiological and clinical research. Unlike gonorrhea and syphilis, HSV seems to be distributed homogeneously in the sexually active population. Together with syphilis and chancroid, genital herpes forms a group of diseases called genital ulcer disease because of the dermatological eruptions they can cause. Patients with symptomatic genital herpes can be treated topically with acylovir to moderate severity and duration of symptoms. Most often, genital herpes is a fairly benign STD; however, it can be of urgent concern during pregnancy when there can be danger of transmission of the infection to the newborn. Neonatal herpes causes frequent morbidity and even mortality, but infants who are delivered by cesarean section avoid risk of transmission, as do infants born to women with no recent symptomatic outbreaks.

Human papillomavirus infection (HPV). This disease, most often manifested as genital warts, is the most common viral STD. Although case surveillance of HPV is relatively poor worldwide, physicians report seeing increases in numbers of cases. The wart (condyloma acuminata) that is seen in about 30 percent of all HPV patients is usually a small, pimply tumor, pigmented or nonpigmented, with fingerlike projections. In women with HPV, it is commonly seen in the lower genital tract; in men, it can appear at various sites in the genital region. The presence of HPV in the cervix and vulva is cause for concern. Certain HPV DNA types have been found in more than 90 percent of patients with certain forms of genital tract cancer, and it is therefore thought that the HPV infections caused by these HPV DNA types are precursors of later cancers in women. Although the clinical management of HPV varies greatly, several therapies, including physical agents (e.g., electrocautery) and immunotherapy, are available and widely used.

HIV and other STDs. HIV (technically, also an STD when it is, in fact, sexually transmitted) and AIDS disproportionately affected white homosexual and bisexual men in the early stages of the epidemic (early 1980s) in the United States, but as the epidemic was spread and diagnosed around the world, the epidemiology of the disease varied by geographical region, influenced greatly by cultural differences. In the United States, the epidemic later appeared in subpopulations of injecting drug users, most of whom were members of racial/ethnic minorities. Since 1989, the group in the United States showing the greatest increase in reported HIV infection has been the group infected through heterosexual transmission, especially in subpopulations in which STDs are most prevalent (Wasserheit 1994). Persons with STDs, especially those infected with genital ulcer disease, appear to be at elevated risk for acquiring an HIV from an infected sex partner. A person who is co-infected (HIV and an STD) is also more likely to transmit HIV to a sex partner than one who is infected with HIV alone. Thus, an important strategy for modulating the HIV epidemic throughout the world is the successful prevention of all STDs and the successful treatment of curable STDs.

Another Important STD

Trichomoniasis is caused by trichomonas vaginalis, a protozoan pathogen, or type of parasite. Despite being the most common of all STDs of consequence, data on its global occurrence are badly inadequate. This disease, transmitted mainly by sexual intercourse, is manifested by vaginitis in women (approximately 50% of those infected have symptoms) and urethritis in men. Men have symptoms for only a brief period, but can easily transmit the parasite to their female sex partners during that period. Metronidazole, usually as a single oral dose, is the effective treatment of choice for trichomoniasis. This common disease, despite seldom resulting in clinical complications, has recently increased in priority for clinicians and prevention programs as new studies have shown that genital inflammation associated with trichomoniasis greatly increases the risk of acquiring other STDs, including HIV. It is thought, that in some populations of the world, the high prevalence of trichomoniasis may explain the explosiveness of the HIV epidemic they have experienced. Unfortunately, laboratory tests for diagnosis are not always available in developing nations.

Global Distribution and Epidemiology of STDs

The World Health Organization estimated that 340 million new cases of curable STDs (limited to gonorrhea, syphilis, chlamydia, and trichomoniasis) occurred in the world in 1999 (Table 1). The largest number of new cases (incidence) occurred in the region of the world denoted by South and Southeast Asia. But, the highest prevalence (number of cases at any point in time per 1,000 population, ages fifteen to forty-nine) occurred in sub-Saharan Africa, meaning that at any random time during 1999, approximately 119 out of 1,000 persons, ages fifteen to forty-nine, were infected with one of these four STDs, or nearly one out of every nine people.

To understand why the global distribution of STDs is so highly differentiated and why cases occur in such geographically and culturally focal patterns is not a straightforward challenge. There are so many factors involved from which to hypothesize, even in industrialized countries. Two recent surveys of sexual behavior conducted in the United States and United Kingdom, where STD and HIV rates are lower, provide useful information, and clues, for comparison purposes. In both countries, the overwhelming majority of the population does not engage in high-risk sexual behaviors. Both surveys reported nearly identical mean numbers of sexual partners, but, in the United States, there were greater proportions of those who reported no or a high number of sex partners, and further, sexual behaviors and attitudes were more polarized in the United States. It was conjectured that the higher rates of STDs, including HIV, in the United States were attributable to the higher proportion of the population with greater numbers of sex partners and to restricted attitudes toward sexuality that made prevention efforts difficult (Michael 1998).

Because not all STDs are widely reportable in many countries, the task of understanding the worldwide epidemiologies of STDs is made more complex. Data on STDs from most of the world is incomplete at best, and in industrialized nations, is limited. In general, data on STDs from many European countries, the United States, Australia, and New Zealand showed increasing incidences of STDs in the 1960s and 1970s, with the bacterial

STDs leveling off then declining since then, but the viral STDs continuing to increase. Of course, the extent of diagnoses and the technologies available to make diagnoses must be seriously taken into consideration in any examination of temporal STD trends. Syphilis probably fluctuates in incidence more widely than any other STD, with cyclic epidemics, in particular, seen in the United States nearly every decade since the discovery of penicillin. Since the dissolution of Russia, an explosive outbreak of STDs has occurred in its respective states, including large syphilis epidemics in the late 1990s in Belarus, Ukraine, and Kyrgyzstan (Eng and Butler 1997).

Openness about sexuality may be a crucial factor in prevention of STDs, an observation from industrialized nations that may be applicable to developing countries. For example, Scandinavia and some northern and western European countries have levels of sexual activity comparable to those reported in the United States, but these countries report much lower rates of unintended pregnancies and STDs. This may be attributable to the pragmatic, open attitudes toward sexuality in these countries that are manifested in mass media interventions, school-based sexual education, and public discussion about sexual health. It can be hypothesized that this openness also translates into openness between parent and child, and between sex partners. This may be relevant to understanding relative low STD and unintended pregnancy rates observed in these countries.

Another possible factor that may partially explain differences in STD rates among industrialized countries is access to medical care. In the United States, many young people who are at elevated risk for STDs do not have medical care, and thus do not routinely access clinical services where regular STD screening tests and counseling can occur. This factor is given credibility by the scant differences in viral STD rates between the United States and other industrialized countries, and larger differences in rates of curable STDs. Other possible factors include the higher use of crack cocaine in the United States, often strongly associated with STD risk, occurrences of sexual violence toward women, and the lack of regulation, or legalization, of prostitution in the United States.

Conclusion

Recent calls for changes in public policy in the United States have cited the "hidden epidemic" of STDs in the United States, an epidemic that is characterized as hidden from view, cloaked in nondisclosure, stigmatizing attitudes, avoidance of medical care, and a byproduct of a society not prone to discuss sexual behaviors and sexuality openly (Eng and Butler 1997). This hidden epidemic is fortified by social norms that do not promote healthy, sexual behavior. If true, this realization may explain differences in reported STD rates among industrialized nations and may be instrumental in elevated STD rates in many developing countries. Bringing the hidden epidemic out into the open may be the key to major progress in STD prevention in the United States and in other parts of the world.

However, there are other related and unrelated factors to consider when trying to understand why these ancient diseases continue to plague the globe, despite the fact that nearly all are preventable and most are curable. People throughout the world are becoming sexually active at younger ages, having more sex partners earlier in life, getting married later in life, and, in general, exposing themselves more often to the risk of acquiring STDs. World governments, by means of acceptance, greater commitment, and enlightened policies, and through better health care and expanded prevention programs, must address STD epidemics on multiple fronts. Despite the responsibilities of governments, international health organizations, and faith and volunteer-based organizations, individuals must also shoulder responsibilities and be sexually cautious, decrease their risks of acquiring and transmitting STDs, and access routine medical care to protect their own health and that of their sex partners and children.

See also:Acquired Immunodeficiency Syndrome (AIDS); Family Planning; Rape; Sexual Communication: Couple Relationships; Sexuality; Sexuality Education

Bibliography

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Other Resources

national center for hiv, std, and tb prevention. (2002). "sexually transmitted disease facts and information." available from www.cdc.gov/nchstp/dstd/disease_info.htm.

world health organization. (2001). "global prevalence and incidence of selected curable transmitted infections—overview and estimates." available from www.who.int/emc-documents/stis/whocdscsredc200110c.html.

ronald r. fichtner

Sexually transmitted diseases (STDS)

Sexually transmitted diseases (STDs) vary in their susceptibility to treatment, their signs and symptoms, and the consequences if they are left untreated. Some are caused by bacteria . These usually can be treated and cured. Others are caused by viruses and can typically be treated but not cured. As of June 2002, recent advancements in diagnosis now allow the identification of more than 15 million new cases of STD in the United States each year.

Long known as venereal disease, after Venus, the Roman goddess of love, sexually transmitted diseases are increasingly common. The more than 20 known sexually transmitted diseases range from the life-threatening to painful and unsightly. The life-threatening sexually transmitted diseases include syphilis , which has been known for centuries, some forms of hepatitis , and Acquired Immune Deficiency Syndrome (AIDS ), which was first identified in 1981.

Most sexually transmitted diseases can be treated successfully, although untreated sexually transmitted diseases remain a huge public health problem. Untreated sexually transmitted diseases can cause everything from blindness to infertility. While AIDS is the most widely publicized sexually transmitted disease, others are more common. More than 13 million Americans of all backgrounds and economic levels develop sexually transmitted diseases every year. Prevention efforts focus on teaching the physical signs of sexually transmitted diseases, instructing individuals on how to avoid exposure, and emphasizing the need for regular check-ups.

The history of sexually transmitted disease is controversial. Some historians argue that syphilis emerged as a new disease in the fifteenth century. Others cite Biblical and other ancient texts as proof that syphilis and perhaps gonorrhea were ancient as well as contemporary burdens. The dispute can best be understood with some knowledge of the elusive nature of gonorrhea and syphilis, called "the great imitator" by the eminent physician William Osler (1849–1919).

No laboratory tests existed to diagnose gonorrhea and syphilis until the late nineteenth and early twentieth centuries. This means that early clinicians based their diagnosis exclusively on symptoms, all of which could be present in other illnesses. Symptoms of syphilis during the first two of its three stages include chancre sores, skin rash, fever, fatigue, headache, sore throat, and swollen glands. Likewise, many other diseases have the potential to cause the dire consequences of late-stage syphilis. These range from blindness to mental illness to heart disease to death. Diagnosis of syphilis before laboratory tests were developed was complicated by the fact that most symptoms disappear during the third stage of the disease.

Symptoms of gonorrhea may also be elusive, particularly in women. Men have the most obvious symptoms, with inflammation and discharge from the penis from two to ten days after infection. Symptoms in women include a painful sensation while urinating or abdominal pain. However, women may be infected for months without showing any symptoms. Untreated gonorrhea can cause infertility in women and blindness in infants born to women with the disease.

The nonspecific nature of many symptoms linked to syphilis and gonorrhea means that historical references to sexually transmitted disease are open to different interpretations. There is also evidence that sexually transmitted disease was present in ancient China.

During the Renaissance, syphilis became a common and deadly disease in Europe. It is unclear whether new, more dangerous strains of syphilis were introduced or whether the syphilis which emerged at that time was, indeed, a new illness. Historians have proposed many arguments to explain the dramatic increase in syphilis during the era. One argument suggests that Columbus and other explorers of the New World carried syphilis back to Europe. In 1539, the Spanish physician Rodrigo Ruiz Diaz de Isla treated members of the crew of Columbus for a peculiar disease marked by eruptions on the skin. Other contemporary accounts tell of epidemics of syphilis across Europe in 1495.

The abundance of syphilis during the Renaissance made the disease a central element of the dynamic culture of the period. The poet John Donne (1572-1631) was one of many thinkers of that era who saw sexually transmitted disease as a consequence of man's weakness. Shakespeare (1564-1616) also wrote about syphilis, using it as a curse in some plays and referring to the "tub of infamy," a nickname for a common medical treatment for syphilis. The treatment involved placing syphilitic individuals in a tub where they received mercury rubs. Mercury, which is now known to be a toxic chemical, did not cure syphilis, but is thought to have helped relieve some symptoms. Other treatments for syphilis included the induction of fever and the use of purgatives to flush the system.

The sculptor Benvenuto Cellini (1500–1571) is one of many individuals who wrote about their own syphilis during the era: "The French disease, for it was that, remained in me more than four months dormant before it showed itself." Cellini's reference to syphilis as the "French disease" was typical of Italians at the time and reflects a worldwide eagerness to place the origin of syphilis far away from one's own home. The French, for their part, called it the "Neapolitan disease," and the Japanese called it the "Portuguese disease." The name syphilis was bestowed on the disease by the Italian Girolamo Fracastoro (1478–1553), a poet, physician, and scientist. Fracastoro created an allegorical story about syphilis in 1530 entitled "Syphilis, or the French Disease." The story proposed that syphilis developed on Earth after a shepherd named Syphilis foolishly cursed at the Sun. The angry Sun retaliated with a disease that took its name from the foolish shepherd, who was the first individual to get sick.

For years, medical experts used syphilis as a catch-all diagnosis for sexually transmitted disease. Physicians assumed that syphilis and gonorrhea were the same thing until 1837, when Philippe Ricord (1800–1889) reported that syphilis and gonorrhea were separate illnesses. The late nineteenth and early twentieth centuries saw major breakthroughs in the understanding of syphilis and gonorrhea. In 1879, Albert Neisser (1855–1916) discovered that gonorrhea was caused by a bacillus, which has since been named Neisseria gonorrhoeae. Fritz Richard Schaudinn (1871–1906) and Paul Erich Hoffmann (1868–1959) identified a special type of spirochete bacteria, now known as Treponema pallidum, as the cause of syphilis in 1905.

Further advances occurred quickly. August von Wassermann (1866–1925) developed a blood test for syphilis in 1906, making testing for syphilis a simple procedure for the first time. Just four years later in 1910, the first effective therapy for syphilis was introduced in the form of Salvarsan, an organic arsenical compound. The compound was one of many effective compounds introduced by the German physician Paul Ehrlich (1854–1915), whose argument that specific drugs could be effective against microorganisms has proven correct. The drug is effective against syphilis, but it is toxic and even fatal to some patients.

The development of Salvarsan offered hope for individuals with syphilis, but there was little public understanding about how syphilis was transmitted in the early twentieth century. In the United States, this stemmed in part from government enforcement of laws prohibiting public discussion of certain types of sexual information. One popular account of syphilis from 1915 erroneously warned that one could develop syphilis after contact with whistles, pens, pencils, toilets, and toothbrushes.

In a tragic chapter in American history, some members of the U.S. Public Health Service exploited the ignorance of the disease among the general public as late as the mid-twentieth century in order to study the ravages of untreated syphilis. The Tuskegee Syphilis Study was launched in 1932 by the U.S. Public Health Service. The almost 400 black men who participated in the study were promised free medical care and burial money. Although effective treatments had been available for decades, researchers withheld treatment, even when penicillin became available in 1943, and carefully observed the unchecked progress of symptoms. Many of the participants fathered children with congenital syphilis, and many died. The study was finally exposed in the media in the early 1970s. When the activities of the study were revealed, a series of new regulations governing human experimentation were passed by the government.

A more public discussion of sexually transmitted disease was conducted by the military during World Wars I and II. During both wars, the military conducted aggressive public information campaigns to limit sexually transmitted disease among the armed forces. One poster from World War II showed a grinning skull on a woman dressed in an evening gown striding along with German Chancellor Führer Adolf Hitler and Japanese Emperor Hirohito. The poster's caption reads "V.D. Worst of the Three," suggesting that venereal disease could destroy American troops faster than either of America's declared enemies.

Concern about the human cost of sexually transmitted disease helped make the production of the new drug penicillin a wartime priority. Arthur Fleming (1881–1955), who is credited with the discovery of penicillin, first observed in 1928 that the penicillium mold was capable of killing bacteria in the laboratory; however, the mold was unstable and difficult to produce. Penicillin was not ready for general use or general clinical testing until after Howard Florey (1898–1968) and Ernst Boris Chain (1906–1979) developed ways to purify and produce a consistent substance.

The introduction of penicillin for widespread use in 1943 completed the transformation of syphilis from a life–threatening disease to one that could be treated relatively easily and quickly. United States rates of cure were 90–97% for syphilis by 1944, one year after penicillin was first distributed in the country. Death rates dropped dramatically. In 1940, 10.7 out of every 100,000 people died of syphilis. By 1970, it was 0.2 per 100,000.

Such progress infused the medical community with optimism. A 1951 article in the American Journal of Syphilis asked, "Are Venereal Diseases Disappearing?" By 1958, the number of cases of syphilis had dropped to 113,884 from 575,593 in 1943, the year penicillin was introduced.

Venereal disease was not eliminated, and sexually transmitted diseases continue to ravage Americans and others in the 1990s. Though penicillin has lived up to its early promise as an effective treatment for syphilis, the number of cases of syphilis has increased since 1956. In addition, millions of Americans suffer from other sexually transmitted diseases, many of which were not known a century or more ago, such as Acquired Immune Deficiency Syndrome (AIDS) caused by the HIV virus. By the 1990s, sexually transmitted diseases were among the most common infectious diseases in the United States.

Some sexually transmitted diseases are seen as growing at epidemic rates. For example, syphilis, gonorrhea, and chancroid, which are uncommon in Europe, Japan and Australia, have increased at epidemic rates among certain urban minority populations. A 1990 study found the rate of syphilis was more than four times higher among blacks than among whites. The Public Health Service reports that as many as 30 million Americans have been affected by genital herpes . Experts have also noted that sexually transmitted disease appears to increase in areas where AIDS is common.

Shifting sexual and marital habits are two factors behind the growth in sexually transmitted disease. Americans are more likely to have sex at an earlier age than they did in years past. They also marry later in life than Americans did two to three decades ago, and their marriages are more likely to end in divorce. These factors make Americans more likely to have many sexual partners over the course of their lives, placing them at greater risk of sexually transmitted disease.

Public health officials report that fear and embarrassment continue to limit the number of people willing to report signs of sexually transmitted disease.

All sexually transmitted diseases have certain elements in common. They are most prevalent among teenagers and young adults, with nearly 66% occurring in people under 25. In addition, most can be transmitted in ways other than through sexual relations. For example, AIDS and Hepatitis B can be transmitted through contact with tainted blood, but they are primarily transmitted sexually. In general, sexual contact should be avoided if there are visible sores, warts, or other signs of disease in the genital area. The risk of developing most sexually transmitted diseases is reduced by using condoms and limiting sexual contact—but can only be reduced to zero by having monogamous (one partner) sexual relations between partners who are free of disease or vectors of disease (e.g., the HIV virus).

Bacterial sexually transmitted diseases include syphilis, gonorrhea, chlamydia, and chancroid. Syphilis is less common than many other sexually transmitted diseases in the Unites States, with 134,000 cases in 1990. The disease is thought to be more difficult to transmit than many other sexually transmitted diseases. Sexual partners of an individual with syphilis have about a 10% chance of developing syphilis after one sexual contact, but the disease has come under increasing scrutiny as researchers have realized how easily the HIV virus which causes AIDS can be spread through open syphilitic chancre sores.

Gonorrhea is far more common than syphilis, with approximately 750,000 cases of gonorrhea reported annually in the United States. The gonococcus bacterium is considered highly contagious. Public health officials suggest that all individuals with more than one sexual partner should be tested regularly for gonorrhea. Penicillin is no longer the treatment of choice for gonorrhea, because of the numerous strains of gonorrhea that are resistant to penicillin. Newer strains of antibiotics have proven to be more effective. Gonorrhea infection overall has diminished in the United States, but the incidence of gonorrhea among certain populations (e.g., African-Americans) has increased.

Chlamydia infection is considered the most common sexually transmitted disease in the United States. About four million new cases of chlamydia infection are reported every year. The infection is caused by the bacterium Chlamydia trachomatis. Symptoms of chlamydia are similar to symptoms of gonorrhea, and the disease often occurs at the same time as gonorrhea. Men and women may have pain during urination or notice an unusual genital discharge one to three weeks after exposure. However, many individuals, particularly women, have no symptoms until complications develop.

Complications resulting from untreated chlamydia occur when the bacteria has a chance to travel in the body. Chlamydia can result in pelvic inflammatory disease in women, a condition which occurs when the infection travels up the uterus and fallopian tubes. This condition can lead to infertility. In men, the infection can lead to epididymitis, inflammation of the epididymis, a structure on the testes where spermatozoa are stored. This too can lead to infertility. Untreated chlamydia infection can cause eye infection or pneumonia in babies of mothers with the infection. Antibiotics are successful against chlamydia.

The progression of chancroid in the United States is a modern-day indicator of the migration of sexually transmitted disease. Chancroid, a bacterial infection caused by Haemophilus ducreyi, was common in Africa and rare in the United States until the 1980s. Beginning in the mid-1980s, there were outbreaks of chancroid in a number of large cities and migrant-labor communities in the United States. The number of chancroid cases increased dramatically during the last two decades of the twentieth century.

In men, who are most likely to develop chancroid, the disease is characterized by painful open sores and swollen lymph nodes in the groin. The sores are generally softer than the harder chancre seen in syphilis. Women may also develop painful sores. They may feel pain urinating and may have bleeding or discharge in the rectal and vaginal areas. Chancroid can be treated effectively with antibiotics.

As of June 2002, there are no cures for the sexually transmitted diseases caused by viruses: AIDS, genital herpes, viral hepatitis, and genital warts. Treatment to reduce adverse symptoms is available for most of these diseases, but the virus cannot be eliminated from the body.

AIDS is the most life-threatening sexually transmitted disease, a disease which is usually fatal and for which there is no cure. The disease is caused by the human immunodeficiency virus (HIV), a virus which disables the immune system , making the body susceptible to injury or death from infection and certain cancers. HIV is a retrovirus which translates the RNA contained in the virus into DNA , the genetic information code contained in the human body. This DNA becomes a part of the human host cell. The fact that viruses become part of the human body makes them difficult to treat or eliminate without harming the patient.

HIV can remain dormant for years within the human body. More than 800,000 cases of AIDS have been reported in the United States Centers for Disease Control since the disease was first identified in 1981, and at least one million other Americans are believed to be infected with the HIV virus. Initial symptoms of AIDS include fever, headache, or enlarged lymph nodes. Later symptoms include energy loss, frequent fever, weight loss, or frequent yeast infections. HIV is transmitted most commonly through sexual contact or through use of contaminated needles or blood products. The disease is not spread through casual contact, such as the sharing of towels, bedding, swimming pools, or toilet seats.

Genital herpes is a widespread, recurrent, and incurable viral infection. Almost a million new cases are reported in the United States annually. The prevalence of herpes infection reflects the highly contagious nature of the virus. About 75% of the sexual partners of individuals with the infection develop genital herpes.

The herpes virus is common. Most individuals who are exposed to one of the two types of herpes simplex virus never develop any symptoms. In these cases, the herpes virus remains in certain nerve cells of the body, but does not cause any problems. Herpes simplex virus type 1 most frequently causes cold sores on the lips or mouth, but can also cause genital infections. Herpes simplex virus type 2 most commonly causes genital sores, though mouth sores can also occur due to this type of virus.

In genital herpes, the virus enters the skin or mucous membrane, travels to a group of nerves at the end of the spinal cord, and initiates a host of painful symptoms within about one week of exposure. These symptoms may include vaginal discharge, pain in the legs, and an itching or burning feeling. A few days later, sores appear at the infected area. Beginning as small red bumps, they can become open sores which eventually become crusted. These sores are typically painful and last an average of two weeks.

Following the initial outbreak, the virus waits in the nerve cells in an inactive state. A recurrence is created when the virus moves through the nervous system to the skin. There may be new sores or simply a shedding of virus which can infect a sexual partner. The number of times herpes recurs varies from individual to individual, ranging from several times a year to only once or twice in a lifetime. Occurrences of genital herpes may be shortened through use of an antiviral drug which limits the herpes virus's ability to reproduce itself.

Genital herpes is most dangerous to newborns born to pregnant women experiencing their first episode of the disease. Direct newborn contact with the virus increases the risk of neurological damage or death. To avoid exposure, physicians usually deliver babies using cesarean section if herpes lesions are present.

Hepatitis, an inflammation of the liver, is a complicated illness with many types. Millions of Americans develop hepatitis annually. The hepatitis A virus, one of four types of viral hepatitis, is most often spread by contamination of food or water. The hepatitis B virus is most often spread through sexual contact, through the sharing of intravenous drug needles, and from mother to child. Hospital workers who are exposed to blood and blood products are also at risk. Hepatitis C and Hepatitis D (less commonly) may also be spread through sexual contact.

A yellowing of the skin, or jaundice, is the best known symptom of hepatitis. Other symptoms include dark and foamy urine and abdominal pain. There is no cure for hepatitis, although prolonged rest usually enables individuals with the disease to recover completely.

Many people who develop hepatitis B become carriers of the virus for life. This means they can infect others and face a high risk of developing liver disease. There are as many as 350 million carriers worldwide, and about 1.5 million in the United States. A vaccination is available against hepatitis B.

The link between human papillomavirus, genital warts, and certain types of cancer has drawn attention to the potential risk of genital warts. There are more than 60 types of human papillomavirus. Many of these types can cause genital warts. In the United States, about 1 million new cases of genital warts are diagnosed every year.

Genital warts are very contagious, and about two-thirds of the individuals who have sexual contact with someone with genital warts develop the disease. There is also an association between human papillomavirus and cancer of the cervix, anus, penis, and vulva. This means that people who develop genital warts appear to be at a higher risk for these cancers and should have their health carefully watched. Contact with genital warts can also damage infants born to mothers with the problem.

Genital warts usually appear within three months of sexual contact. The warts can be removed in various ways, but the virus remains in the body. Once the warts are removed the chances of transmitting the disease are reduced.

Many questions persist concerning the control of sexually transmitted diseases. Experts have struggled for years with efforts to inform people about transmission and treatment of sexually transmitted disease. Frustration over the continuing increase in sexually transmitted disease is one factor which has fueled interest in potential vaccines against certain sexually transmitted diseases.

A worldwide research effort to develop a vaccine against AIDS has resulted in a series of vaccinations now in clinical trials. Efforts have focused in two areas, finding a vaccine to protect individuals against the HIV virus and finding a vaccine to prevent the progression of HIV to AIDS in individuals who already have been exposed to the virus. One of many challenges facing researchers has been the ability of the HIV virus to change, making efforts to develop a single vaccine against the virus futile.

Researchers also are searching for vaccines against syphilis and gonorrhea. Experiments conducted on prisoners more than 40 years ago proved that some individuals could develop immunity to syphilis after inoculation with live Treponema pallidum, but researchers have still not been able to develop a vaccine against syphilis which is safe and effective. In part this stems from the unusual nature of the syphilis bacteria, which remain potentially infectious even when its cells are killed. An effective gonorrhea vaccine has also eluded researchers.

Immunizations are available against Hepatitis A and Hepatitis B (Hepatitis D is prevented by the Hepatitis B vaccine). The virus that causes Hepatitis C, however, is able to change its form (mutate) quite rapidly, thereby hampering efforts to develop a vaccine against it.

Without vaccinations for most of the sexually transmitted diseases, health officials depend on public information campaigns to limit the growth of the diseases. Some critics have claimed that the increasing incidence of sexually transmitted diseases suggest that current techniques are failing. In other countries, however, the incidence of sexually transmitted disease has fallen during the same period it has risen in the United States. For example, in Sweden the gonorrhea rate fell by more than 95% from 1970 to 1989 after vigorous government efforts to control sexually transmitted disease in Sweden.

Yet the role of government funding for community health clinics, birth control, and public information campaigns on sexually transmitted disease has long been controversial. Public officials continue to debate the wisdom of funding public distribution of condoms and other services that could affect the transmission of sexually transmitted disease. Although science has made great strides in understanding the causes and cures of many sexually transmitted diseases, society has yet to reach agreement on how best to attack them.

See also Bacteria and bacterial infection; Immunization; Immunogenetics; Public health, current issues; Virus replication; Viruses and responses to viral infection

SEXUALLY TRANSMITTED DISEASES

Sexually transmitted diseases (STDs) are caused by a group of infectious microorganisms that are transmitted mainly through sexual activity. These agents represent a costly, burdensome global public health problem. STDs can cause harmful, often irreversible, clinical complications, including reproductive health problems, fetal and perinatal health problems, and cancer, and they are also linked in a causal chain of events to the sexual transmission of human immunodeficiency virus (HIV) infection. Although STDs are largely preventable through behavior modification and sound primary health care, they are under-recognized and under-appreciated as a public health problem by most healthcare providers, the general public, and healthcare policy makers. In 1997, the Institute of Medicine characterized STDs as "hidden epidemics of tremendous health and economic consequence" in the United States and advocated urgent national preventive action.

An estimated 333 million curable STDs occur annually worldwide. In the United States, STDs are among the most frequently reported infectious diseases nationwide. Each year an estimated 15 million new cases of STDs occur in Americans, including nearly 4 million infections in U.S. teenagers. The annual direct and indirect costs of the principal STDs, including sexually transmitted HIV infection, and their complications are estimated at $17 billion.

More than twenty-five bacteria, viruses, protozoa, and yeasts are considered sexually transmissible. Bacterial STDs include those caused by Chlamydia trachomatis (chlamydia), Neisseria gonorrhoeae (gonorrhea), Treponema pallidum (syphilis), Haemophilus ducreyi (chancroid), and other common sexually transmitted organisms. Chlamydia and gonorrhea cause inflammatory reactions in the host. In women, these organisms can ascend into the upper reproductive tract where pelvic inflammatory disease (PID) can cause irreparable damage to the reproductive organs and result in infertility, ectopic pregnancy, and chronic pelvic pain. In its early stages, syphilis causes painless genital ulcers and other infectious lesions. Left untreated, syphilis moves through the body in stages, damaging many organs over time. Chancroid is associated with painful genital lesions. In pregnant women, acute bacterial STDs can cause potentially fatal congenital infections or perinatal complications, such as eye and lung infections in the newborn. Effective single-dose antimicrobials can cure chlamydia, gonorrhea, syphilis, and chancroid.

Viral STDs include the sexually transmitted viral infections caused by human immunodeficiency virus (HIV infection), herpes simplex virus type 2 (genital herpes), and human papillomavirus (HPV infection). Initial infections with these organisms may be asymptomatic or cause only mild symptoms. Treatable but not curable, viral STDs appear to be lifelong infections. HIV is the virus that causes acquired immunodeficiency syndrome (AIDS). Herpes causes periodic outbreaks of painful genital lesions. Some strains of HPV cause genital warts, and others are important risk factors for cervical dysplasia and invasive cervical cancer. Hepatitis B virus (HBV) is another acute viral illness that can be transmitted through sexual activity. Most persons who acquire HBV infection recover and have no complications, but it can sometimes become a chronic health problem.

Trichomonas vaginalis (trichomoniasis) is a common protozoal STD, and Candida species (candidiasis) are sexually transmitted yeasts. Both are frequently associated with vaginal discharge.

BIOLOGICAL FACTORS IN THE SPREAD OF STDS

STDs are behavior-linked diseases that result from unprotected sex. Nonetheless, several biological factors contribute to their spread. These include the asymptomatic nature of STDs, the long lag time between infections and complications, the higher susceptibility of women to STDs, and the way that STDs facilitate the transmission of HIV infection.

The silent nature of STDs represents their greatest public health threat. Most STDs cause some symptomatic illness, but many produce symptoms so mild or nonspecific that infected persons are not alerted to seek medical care. As many as one in three men and two in three women with chlamydia infection have no obvious signs of infection. Without treatment or other interventions, infected persons can continue to infect new sex partners. Moreover, serious complications that cause irreversible damage can occur "silently" before any symptoms are apparent. A related problem is the long interval that can elapse between acquiring an STD and recognizing a clinically significant health problem. Women can develop cervical cancer many years after infection with some strains of HPV. A woman may first suspect she had an asymptomatic infection with chlamydia or gonorrhea when she finds out later in life that she is infertile or has an ectopic pregnancy. Because the original infection was likely to have been asymptomatic, there is frequently no perceived connection between the original sexually acquired infection and the resulting health problem. The lack of awareness of this connection leads people to underestimate their risk and to forego preventive precautions.

Gender and age are also associated with increased risk for STDs. Women are at higher risk than men for most STDs, and young women are more susceptible to certain infections than older women. Due to cervical ectopy that is extremely common in adolescent females, the immature cervix of adolescent females is covered with cells that are especially susceptible to STDs such as chlamydia.

The presence of other STDs, especially those that cause genital ulcers or inflammation, influences the sexual transmission and acquisition of HIV infection. Studies have repeatedly demonstrated that people are two to five times more likely to become infected with HIV through sexual contact when other STDs are present. In addition, dually infected persons (persons who are infected with both HIV and another STD) are more likely to transmit HIV infection during sexual contact. Conversely, effective STD detection and treatment can slow the spread of HIV infection at the individual and community levels. For example, in a study in Malawi in the mid-1990s, treatment of gonorrhea in HIV-infected men returned the frequency and concentration of HIV genetic material in semen to levels comparable to levels found in HIV-infected men who were not infected with other STDs. Similarly, a community trial in Tanzania in the mid-1990s demonstrated that treatment of symptomatic STDs resulted in a 42-percent decrease in new heterosexually transmitted HIV infections.

SOCIAL FACTORS THAT AFFECT THE SPREAD OF STDS

Some social factors directly affect STD spread especially in vulnerable populations. In addition, the stigma that continues to surround STDs in the United States indirectly interferes with establishing new social norms pertaining to sex and sexuality.

When there are barriers to health care, it is difficult to detect and treat STDs early. Infected persons also miss an opportunity for behavioral change counseling. Health care access barriers keep infected persons in the community where they continue to spread STDs. In the United States, groups with the highest rates of STDs are the same groups in which access to health care services is limited or absent.

Perhaps the greatest social factor contributing to the spread of STDs, and the factor that most significantly separates the United States from industrialized countries with low STD rates, is the stigma that continues to be associated with sexually transmitted infections. Although sex and sexuality pervade many aspects of American culture, most Americans are secretive and private about their sexual behavior. Talking openly and comfortably about sex and sexuality is difficult even in intimate relationships. This secrecy about sexuality and STDs adversely affects STD prevention in the United States by thwarting sexuality and STD education programs for adolescents, hindering communication between parents and children and between sex partners, promoting unbalanced sexual messages in the media, obstructing education and counseling activities, and impeding research on sexual behaviors.

GROUPS DISPROPORTIONATELY AFFECTED BY STDS

All racial, cultural, economic, and religious groups are affected by STDs, and people in all communities and sexual networks are at risk. Nevertheless, some persons are disproportionately affected by STDs and their complications.

STDs disproportionately affect disenfranchised persons and individuals who are in social networks characterized by high-risk sexual behaviors, substance abuse, and limited access to health care. Some notable disproportionately affected groups include sex workers, homeless persons and runaways, adolescents and adults in detention, and migrant workers. Many studies document the association of substance use, especially alcohol and drug use, with STDs. The introduction of illicit substances into communities can dramatically alter sexual behavior in high-risk sexual networks leading to epidemic spread of STDs. The national U.S. syphilis epidemic of the late 1980s was fueled by the effect of increased crack cocaine use, especially in minority communities. Crack cocaine led to increases in sex exchanged for drugs and in the number of anonymous sex partners and decreased health care-seeking behavior and motivation to use barrier protection—all factors that can increase STD transmission in a community. Other substances, including alcohol, can also affect a person's cognitive and negotiating skills before and during sex, lowering the likelihood that preventive action will be taken to protect against STDs and pregnancy.

Gender disparities are an important aspect of the epidemiology of STDs. Compared to men, women suffer more frequent and serious STD complications, including PID, ectopic pregnancy, infertility, and chronic pelvic pain. Women are biologically more susceptible to infection when exposed to a sexually transmitted agent, and STDs are often more easily transmitted from a man to a woman than from a woman to a man. Given that some newly acquired STDs (and even some long-term complications) are only mildly symptomatic or completely asymptomatic in women, the combination of increased susceptibility and silent infection frequently results in delayed STD diagnosis and treatment. A further complication is that STDs are more difficult to diagnose in women due to the complex anatomy of the female reproductive tract and the frequent need for a speculum examination and diagnostic culture tests.

In pregnant women, STDs can result in serious health problems or death to a developing fetus or newborn. Sexually transmitted pathogens can be transmitted across the placenta, resulting in congenital infection, or can reach the newborn during vaginal childbirth, resulting in perinatal infection. Regardless of the route of infection, these organisms can permanently damage the fetal or newborn brain, spinal cord, eyes, auditory nerves, or immune system. Even when the organisms do not reach the fetus or newborn directly, they can cause spontaneous abortion, stillbirth, premature rupture of the membranes, and preterm delivery.

For a variety of behavioral, social, and biological reasons, STDs also disproportionately affect adolescents. In 1998, U.S. teenagers 15 to 19 years old had the highest reported rate of chlamydia and the second highest rate of gonorrhea. The herpes infection rate among white youth in the United States aged twelve to nineteen increased nearly fivefold from the late 1970s to the early 1990s. Because not all teenagers are sexually active, the actual rate of STDs among teens is even higher than the observed rates suggest. There are several contributing factors. Many teenagers are, in fact, sexually active and at risk for STDs, and they are having sex with partners from sexual networks that are already highly infected with untreated STDs. In 1999, among U.S. high school youth interviewed for the Youth Risk Behavior Surveillance System survey, half (49.9%) indicated they had had sexual intercourse during their lifetimes. Early sexual activity and multiple sexual partners were commonly reported among American high school youth; 8.3 percent of students indicated they had first had sex before age thirteen, and 16.2 percent said they had four or more sex partners during their lifetime. Despite the supposedly easy access to condoms that can lower STD transmission risk considerably, only 58 percent of sexually active students said they used a condom the last time they had intercourse. Sexually active teenagers are often reluctant to seek STD services or face serious obstacles to obtaining such services. In addition, health care providers are often uncomfortable discussing sexuality and risk reduction with young persons.

Some minority racial and ethnic groups (mainly black and Hispanic populations) in the United States have higher rates of STDs compared with rates for whites. Race and ethnicity in the United States are risk markers that correlate with other more fundamental determinants of health status such as poverty, access to quality health care, health care-seeking behavior, illicit drug use, and living in communities with high STD prevalence. Public health data may over-represent STDs among racial and ethnic groups who are more likely to receive STD services from public sector STD clinics characterized by timely and complete reporting of public health statistics. However, even when random sampling techniques are used to study health problems, higher rates of STDs are often found among African Americans and Hispanics compared with whites.

FACTORS IMPORTANT TO THE PREVENTION AND CONTROL OF STDS

The dynamics of how STDs spread in populations have been studied extensively to derive approaches to prevention and control. Three main factors predict how fast and at what level STDs will spread in a population: the nature of sexual relationships, the degree to which susceptibility to STDs can be modified, and the timeliness and completeness of treatment.

The nature of sexual relationships refers to the decisions people make about when to become and remain sexually active and whom to select as sex partners. The earlier that vaginal, oral, or anal sexual intercourse begins and the greater the number of lifetime sex partners, the more likely a person is to acquire one or more STDs in a lifetime. Behavioral interventions that help delay the initiation of intercourse and reduce the lifetime number of sex partners will have a positive effect on slowing STD transmission.

Susceptibility to STDs can be modified with vaccines or barrier contraceptives such as condoms. If uninfected persons are somehow immune to STDs, then no transmission will occur. The availability of effective vaccines against STDs could dramatically slow increases in or even eliminate some STDs. For example, there is an effective and widely available vaccine for hepatitis B, a viral STD. Current strategies to immunize all children against hepatitis B before they become sexually active could greatly reduce the societal burden of this disease. Susceptibility can also be altered each time sex occurs. The correct and consistent use of condoms can reduce the rate of STD transmission in a population. Persons who choose to engage in sexual behaviors that place them at risk of STDs should use latex or polyurethane condoms every time they have sex. A condom put on the penis before starting sex and worn until the penis is withdrawn can help protect both the male and the female partner from most STDs. When a male condom cannot be used appropriately, sex partners should consider using a female condom. However, condoms do not provide complete protection from all STDs. Sores and lesions of STDs on infected men and women may be present in areas not covered by the condom, resulting in transmission of infection to a new person. This is common with genital warts and other genital HPV infections.

Although condom use has been on the rise in the United States over the past few decades, women who use the most effective forms of contraception (sterilization and hormonal contraception) are less likely than other women to use condoms for STD prevention. The most effective methods of contraception are not the most effective methods of STD prevention; likewise, methods that give a considerable measure of protection against STDs are considered to be good, but not the most effective, methods of pregnancy prevention. This suggests that, especially for young women who are at highest risk for unwanted pregnancy and STDs, using dual protection (condoms and hormonal contraception) will offer the best overall protection against both.

The third factor in STD prevention and control focuses on finding and treating infected persons and their sex partners. The longer someone has an untreated STD (especially if the person is asymptomatic), the longer that person can potentially infect others. If that interval can be shortened for the millions of persons who acquire STDs each year, then transmission would slow appreciably. Screening and treatment are the biomedical approaches that can be applied to this situation. For STDs that are frequently asymptomatic, screening and treatment also benefit those likely to suffer severe complications (especially women) if infections are not detected and treated early. For example, in the early 1990s, chlamydia screening in a large metropolitan managed-care organization reduced the incidence of subsequent PID in the screened group by 40 percent. Identifying and treating partners of persons with curable STDs has always been an integral part of organized control programs. Theoretically, this can break the chain of transmission in a sexual network. Early antibiotic treatment of a sex partner can interfere with an STD taking hold in a recently exposed person. Partner treatment benefits the original patient by reducing the risk of reinfection, and the partner benefits by avoiding acute infection and potential complications. Because future sex partners are protected by treating partners, this strategy also benefits the community. New screening tests (some of which can be performed on urine specimens) that facilitate STD screening in nontraditional settings are now available.

Many examples demonstrate the effectiveness of organized approaches to STD prevention and control that incorporate these strategies on a large scale. When a sustained, collaborative, multifaceted approach to STD prevention and control is undertaken, dramatic results can be achieved. One need only observe the results of sustained STD prevention efforts in many countries in Western and Northern Europe, Canada, Japan, and Australia, where STD rates are many times lower than in the United States, to conclude that STD prevention programs can work on a national scale.

Allison L. Greenspan

Joel R. Greenspan

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Sexually Transmitted Diseases

Definition

Sexually transmitted disease (STD) is a term used to describe more than 20 different infections that are transmitted through exchange of semen, blood, and other body fluids; or by direct contact with the affected body areas of people with STDs. Sexually transmitted diseases are also called venereal diseases.

Description

The Centers for Disease Control and Prevention (CDC) has reported that 85% of the most prevalent infectious diseases in the United States are sexually transmitted. The rate of STDs in this country is 50 to 100 times higher than that of any other industrialized nation. One in four sexually active Americans will be affected by an STD at some time in his or her life.

About 12 million new STD infections occur in the United States each year. One in four occurs in someone between the ages of 16 and 19. Almost 65% of all STD infections affect people under the age of 25.

Types of STDs

STDs can have very painful long-term consequences as well as immediate health problems. They can cause:

• birth defects
• blindness
• bone deformities
• brain damage
• cancer
• heart disease
• infertility and other abnormalities of the reproductive system
• mental retardation
• death

Some of the most common and potentially serious STDs in the United States include:

• Chlamydia. This STD is caused by the bacterium Chlamydia trachomatis, a microscopic organism that lives as a parasite inside human cells. Although over 526,000 cases of chlamydia were reported in the United States in 1997, the CDC estimates that nearly three million cases occur annually because 75% of women and 50% of men show no symptoms of the disease after infection. Approximately 40% of women will develop pelvic inflammatory disease (PID) as a result of chlamydia infection, a leading cause of infertility.
• Human papillomavirus (HPV). HPV causes genital warts and is the single most important risk factor for cervical cancer in women. Over 100 types of HPV exist, but only about 30 of them can cause genital warts and are spread through sexual contact. In some instances, warts are passed from mother to child during childbirth, leading to a potentially life-threatening condition for newborns in which warts develop in the throat (laryngeal papillomatosis).
• Genital herpes. Herpes is an incurable viral infection thought to be one of the most common STDs in this country. It is caused by one of two types of herpes simplex viruses: HSV-1 (commonly causing oral herpes) or HSV-2 (usually causing genital herpes). The CDC estimates that 45 million Americans (one out of every five individuals 12 years of age or older) are infected with HSV-2; this number has increased 30% since the 1970s. HSV-2 infection is more common in women (one out of every four women) than men (one out of every five men) and in African Americans (45.9%) than Caucasians (17.6%).
• Gonorrhea. The bacterium Neisseria gonorrhoeae is the causative agent of gonorrhea and can be spread by vaginal, oral, or anal contact. The CDC reports that approximately 650,000 individuals are infected with gonorrhea each year in the United States, with 132.2 infections per 100,000 individuals occurring in 1999. Approximately 75% of American gonorrhea infections occur in persons aged 15 to 29 years old. In 1999, 75% of reported gonorrhea cases occurred among African Americans.
• Syphilis. Syphilis is a potentially life-threatening infection that increases the likelihood of acquiring or transmitting HIV. In 1998, the CDC reported approximately 38,000 cases of syphilis in the United States; this included 800 cases of congenital syphilis. Congenital syphilis causes irreversible health problems or death in as many as 40% of all live babies born to women with untreated syphilis.
• Human immunodeficiencyvirus (HIV) infection. In 2000, the CDC reported that 120,223 people in the United States are HIV-positive and 426,350 are living with AIDS. In addition, approximately 1,000-2,000 children are born each year with HIV infection. It is also estimated that 33 million adults and 1.3 million children worldwide were living with HIV/AIDS as of 1999 with 5.4 million being newly infected that year. There is no cure for this STD.

Social groups and STDs

STDs affect certain population groups more severely than others. Women, young people, and members of minority groups are particularly affected. Women in any age bracket are more likely than men to develop medical complications related to STDs. With respect to racial and ethnic categories, the incidence of syphilis is 60 times higher among African Americans than among Caucasians, and four times higher in Hispanics than in Anglos. According to the CDC, in 1999 African Americans accounted for 77% of the total number of gonorrhea cases and nearly 46% of all genital herpes cases.

Causes and symptoms

The symptoms of STDs vary somewhat according to the disease agent (virus or bacterium), the sex of the patient, and the body systems affected. The symptoms of some STDs are easy to identify; others produce infections that may either go unnoticed for some time or are easy to confuse with other diseases. Syphilis in particular can be confused with disorders ranging from infectious mononucleosis to allergic reactions to prescription medications. In addition, the incubation period of STDs varies. Some produce symptoms close enough to the time of sexual contact—often less than 48 hours later%mdash;for the patient to recognize the connection between the behavior and the symptoms. Others have a longer incubation period, so that the patient may not recognize the early symptoms as those of a sexually transmitted infection.

Some symptoms of STDs affect the genitals and reproductive organs:

• A woman who has an STD may bleed when she is not menstruating or has abnormal vaginal discharge. Vaginal burning, itching, and odor are common, and she may experience pain in her pelvic area while having sex
• A discharge from the tip of the penis may be a sign that a man has an STD. Males may also have painful or burning sensations when they urinate.
• There may be swelling of the lymph nodes near the groin area.
• Both men and women may develop skin rashes, sores, bumps, or blisters near the mouth or genitals. Homosexual men frequently develop these symptoms in the area around the anus.

Other symptoms of STDs are systemic, which means that they affect the body as a whole. These symptoms may include:

• fever, chills, and similar flu-like symptoms
• skin rashes over large parts of the body
• arthritis-like pains or aching in the joints
• throat swelling and redness that lasts for three weeks or longer

Diagnosis

A sexually active person who has symptoms of an STD or who has had an STD or symptoms of infection should be examined without delay by one of the following health care professionals:

• a specialist in women's health (gynecologist)
• a specialist in disorders of the urinary tract and the male sexual organs (urologist)
• a family physician
• a nurse practitioner
• a specialist in skin disorders (dermatologist).

The diagnostic process begins with a thorough physical examination and a detailed medical history that documents the patient's sexual history and assesses the risk of infection.

The doctor or other healthcare professional will:

• Describe the testing process. This includes all blood tests and other tests that may be relevant to the specific infection.
• Explain the meaning of the test results.
• Provide the patient with information regarding high-risk behaviors and any necessary treatments or procedures.

The doctor may suggest that a patient diagnosed with one STD be tested forothers, as itspossibletohavemore than one STD at a time. One infection may hide the symptoms of another or create a climate that fosters its growth. At present, it is particularly important that persons who are HIV-positive be tested for syphilis as well.

Notification

The law in most parts of the United States requires public health officials to trace and contact the partners of persons with STDs. Minors, however, can get treatment without their parents' permission. Public health departments in most states can provide information about STD clinic locations; Planned Parenthood facilities provide testing and counseling. These agencies can also help with or assume the responsibility of notifying sexual partners who must be tested and may require treatment.

Treatment

Although self-care can relieve some of the pain of genital herpes or genital warts that has recurred after being diagnosed and treated by a physician, other STD symptoms require immediate medical attention.

Antibiotics are prescribed to treat gonorrhea, chlamydia, syphilis, and other STDs caused by bacteria. Although prompt diagnosis and early treatment almost always cures these STDs, new infections can develop if exposure continues or is renewed.Viral infections can be treated symptomatically with antiviral medications.

Prognosis

The prognosis for recovery from STDs varies among the different diseases. The prognosis for recovery from gonorrhea, syphilis, and other STDs caused by bacteria is generally good, provided that the disease is diagnosed early and treated promptly. Untreated syphilis in particular can lead to long-term complications and disability. Viral STDs (genital herpes, genital warts, HIV) cannot be cured but must be treated on a long-term basis to relieve symptoms and prevent life-threatening complications.

Prevention

Vaccines

Vaccines for the prevention of hepatitis A and hepatitis B are currently recommended for gay and bisexual men, users of illegal drugs, health care workers, and others at risk of contracting these diseases. Vaccines to prevent other STDs are being tested and may be available within several years.

Lifestyle choices

The risk of becoming infected with an STD can be reduced or eliminated by changing certain personal behaviors. Abstaining from sexual relations or maintaining a mutually monogamous relationship with a partner are legitimate options. It is also wise to avoid sexual contact with partners who are known to be infected with an STD, whose health status is unknown, who abuse drugs, or who are involved in prostitution.

Use of condoms and other contraceptives

Men or women who have sex with a partner of known (or unsure) infection should make sure a new condom is used every time they have genital, oral, or anal contact. Used correctly and consistently, male condoms provide good protection against HIV and other STDs such as gonorrhea, chlamydia, and syphilis. Female condoms (lubricated sheaths inserted into the vagina) have also been shown to be effective in preventing HIV and other STDs. Condoms provide a measure of protection against genital herpes, genital warts, and hepatitis B.

Spermicides and diaphragms can decrease the risk of transmission of some STDs. They do not protect women from contracting HIV. Birth-control pills, patches, or injections do not prevent STDs. Neither do surgical sterilization or hysterectomy.

Hygienic measures

Urinating and washing the genital area with soap and water immediately after having sex may eliminate some germs before they cause infection. Douching, however, can spread infection deeper into the womb. It may also increase a woman's risk of developing pelvic inflammatory disease (PID).

Resources

ORGANIZATIONS

National STD Hotline. (800) 227-8922.

Planned Parenthood Federation of America. (800) 230-7526. 〈http://www.planned parenthood.org〉.

OTHER

Sexually Transmitted Diseases. March 24, 2001. 〈http://www.cdc.gov/nchstp/dstd/dstdp.html〉.

KEY TERMS

Chlamydia— A microorganism that resembles certain types of bacteria and causes several sexually transmitted diseases in humans.

Condom— A thin sheath worn over the penis during sexual intercourse to prevent pregnancy or the transmission of STDs. There are also female condoms.

Diaphragm— A dome-shaped device used to cover the back of a woman's vagina during intercourse in order to prevent pregnancy.

Pelvic inflammatory disease (PID)— An inflammation of the tubes leading from a woman's ovaries to the uterus (the Fallopian tubes), caused by a bacterial infection. PID is a leading cause of fertility problems in women.

Venereal disease— Another term for sexually transmitted disease.

Sexually Transmitted Diseases Cultures

Definition

Sexually transmitted diseases are infections spread from person to person through sexual contact. A culture is a test in which a laboratory attempts to grow and identify the microorganism causing an infection.

Purpose

Sexually transmitted diseases (STDs) produce symptoms such as genital discharge, pain during urination, bleeding, pelvic pain, skin ulcers, or urethritis. Often, however, they produce no immediate symptoms. Therefore, the decision to test for these diseases must be based not only the presence of symptoms, but on whether or not a person is at risk of having one or more of the diseases. Activities, such as drug use and sex with more than one partner, put a person at high risk for these diseases.

STD cultures are necessary to diagnose certain types of STDs. Only after the infection is diagnosed can it be treated and further spread of the infection prevented. Left untreated, consequences of these diseases range from discomfort to infertility to death. In addition, these diseases, if present in a pregnant woman, can be passed from mother to fetus.

Description

Gonorrhea, syphilis, chlamydia, chancroid, herpes, human papillomavirus, human immunodeficiency virus (HIV), and mycoplasma are common sexually transmitted diseases. Not all are diagnosed with a culture. For those that are, a sample of material is taken from the infection site, placed in a sterile container, and sent to the laboratory.

Bacterial cultures

In the laboratory, a portion of material from the infection site is spread over the surface of several different types of culture plates and placed in an incubator at body temperature for one to two days. Bacteria present in the sample will multiply and appear on the plates as visible colonies. They are identified by the appearance of their colonies and by the results of biochemical tests and a gram stain. The Gram stain is done by smearing part of a colony onto a microscope slide. After it dries, the slide is stained with purple and red stains, then examined under a microscope. The color of stain picked up by the bacteria (purple or red), the shape (such as round or rectangle), and the size provide valuable clues as to the identity and which antibiotics might work best. Bacteria that stain purple are called Gram-positive; those that stain red are called gram-negative.

The result of the gram stain is available the same day or in less than an hour if requested by the physician. An early report, known as a preliminary report, is usually available after one day. This report will tell if any microorganisms have been found yet, and if so, their Gram stain appearance—for example, a Gramnegative rod or a gram-positive cocci. The final report, usually available in one to seven days, includes complete identification and an estimate of the quantity of the microorganisms isolated.

A sensitivity test, also called antibiotic susceptibility test, commonly done on bacteria isolated from an infection site, is not always done on bacteria isolated from a sexually transmitted disease. These bacteria often are treated using antibiotics that are part of a standard treatment protocol.

GONORRHEA. Neisseria gonorrhoeae, also called gonococcus or GC, causes gonorrhea. It infects the surfaces of the genitourinary tract, primarily the urethra in males and the cervix in females. On a gram stain done on material taken from an infection site, the bacteria appear as small gram-negative diplococci (pairs of round bacteria) inside white blood cells. Neisseria gonorrhoeae grows on a special culture plate called Thayer-Martin (TM) media in an environment with low levels of oxygen and high levels of carbon dioxide.

The best specimen from which to culture Neisseria gonorrhoeae is a swab of the urethra in a male or the cervix in a female. Other possible specimens include vagina, body fluid discharge, swab of genital lesion, or the first urine of the day. Final results usually are available after two days. Rapid nonculture tests are available to test for GC and provide results on the same or following day.

CHANCROID. Chancroid is caused by Haemophilus ducreyi. It is characterized by genital ulcers with nearby swollen lymph nodes. The specimen is collected by swabbing one of these pus-filled ulcers. The gram stain may not be helpful as this bacteria looks just like other Haemophilus bacteria. This bacteria only grows on special culture plates, so the physician must request a specific culture for a person who has symptoms of chancroid. Even using special culture plates, Haemophilus ducreyi is isolated from less than 80% of the ulcers it infects. If a culture is negative, the physician must diagnose chancroid based on the person's symptoms and by ruling out other possible causes of these symptoms, such as syphilis.

MYCOPLASMA. Three types of mycoplasma organisms cause sexually transmitted urethritis in males and pelvic inflammatory disease and cervicitis in females: Mycoplasma hominis, Mycoplasma gentialium, and Ureaplasma urealyticum. These organisms require special culture plates and may take up to six days to grow. Samples are collected from the cervix in a female, the urethra or semen in a male, or urine.

SYPHILIS. Syphilis is caused by Treponema pallidum, one in a group of bacteria called spirochetes. It causes ulcers or chancres at the site of infection. The organism does not grow in culture. Using special techniques and stains, it is identified by looking at a sample of the ulcer or chancre under the microscope. Various blood tests also may be done to detect the treponema organism.

CHLAMYDIA. Chlamydia is caused by the gramnegative baterium Chlamydia trachomatis. It is one of the most common STDs in the United States and generally appears in sexually active adolescents and young adults. While chlamydia often does not have any initial symptoms, it can, if left untreated, lead to pelvic inflammatory disease and sterility. Samples are collected from one or more of these infection sites: cervix in a female, urethra in a male, or the rectum. A portion of specimen is combined with a specific type of cell and allowed to incubate. Special stains are performed on the cultured cells, looking for evidence of the chlamydia organism within the cells. A swab can also be taken from the woman's vulva. Men and women can now be screened for Chlamydia with a urine sample. Urine-based screening has increased screening significantly, especially among men.

Viral cultures

To culture or grow a virus in the laboratory, a portion of specimen is mixed with commercially prepared animal cells in a test tube. Characteristic changes to the cells caused by the growing virus help identify the virus. The time to complete a viral culture varies with the type of virus. It may take several days or up to several weeks.

HERPES VIRUS. Herpes simplex virus type 2 is the cause of genital herpes. Diagnosis is usually made based on the person's symptoms. If a diagnosis needs confirmation, a viral culture is performed using material taken from an ulcer. A Tzanck smear is a microscope test that can rapidly detect signs of herpes infection in cells taken from an ulcer. The culture takes up to 14 days. In 2004, the FDA approved a blood test to detect the antibodies to herpes virus.

HUMAN PAPILLOMAVIRUS. Human papillomavirus causes genital warts. This virus will not grow in culture; the diagnosis is based on the appearance of the warts and the person's symptoms. In late 2003, the U.S. Food and Drug Administration (FDA) approved a human papillomavirus (HPV) DNA test with a Pap smear for screening women age 30 and older. The combined test would help physicians determine which women were at extremely low risk for cervical cancer and which should be more closely monitored.

HIV. Human immunodeficiency virus (HIV) is usually diagnosed with a blood test. Cultures for HIV are possible, but rarely needed for diagnosis. However, newer rapid tests were developed in 2003 and approved by the FDA in 2004. These tests are cheaper and can deliver results in as little as three minutes. The FDA also approved an HIV test in 2004 that can detect HIV in saliva.

Preparation

Generally, the type of specimen depends on the type of infection. Cultures always should be collected before the person begins taking antibiotics. After collection of these specimens, each is placed into a sterile tube containing a liquid in which the organism can survive while in route to the laboratory. The new rapid HIV tests rely on blood samples collected from a finger stick or vein or on saliva collected from the mouth. Initial results are not sent to a lab but are processed onsite.

Urethral specimen

Men should not urinate one hour before collection of a urethral specimen. The physician inserts a sterile, cotton-tipped swab into the urethra.

Cervical specimen

Women should not douche or take a bath within 24 hours of collection of a cervical or vaginal culture. The physician inserts a moistened, nonlubricated vaginal speculum. After the cervix is exposed, the physician removes the cervical mucus using a cotton ball. Next, he or she inserts a sterile cotton-tipped swab into the endocervical canal and rotates the swab with firm pressure for about 30 seconds.

Vaginal specimen

Women should not douche or take a bath within 24 hours of collection of a cervical or vaginal culture. The physician inserts a sterile, cotton-tipped swab into the vagina.

Anal specimen

The physician inserts a sterile, cotton-tipped swab about 1 inch into the anus and rotates the swab for 30 seconds. Stool must not contaminate the swab.

Oropharynx (throat) specimen

The person's tongue is held down with a tongue depressor, as a healthcare worker moves a sterile, cotton-tipped swab across the back of the throat and tonsil region.

Urine specimen

To collect a "clean-catch" urine, the person first washes the perineum, and the penis or labia and vulva. He or she begins urinating, letting the first portion pass into the toilet, then collecting the remainder into a sterile container.

KEY TERMS

Culture— A laboratory test done to grow and identify microorganisms causing infection.

Gram stain— Microsopic examination of a portion of a bacterial colony or sample from an infection site after it has been stained by special stains. Certain bacteria pick up the purple stain; these bacteria are called gram positive. Other bacteria pick up the red stain; these bacteria are called gram negative. The color of the bacteria, in addition to their size and shape, provide clues as to the identity of the bacteria.

Sensitivity test— A test that determines which antibiotics will kill the bacteria isolated from a culture.

Vulva— The external part of the woman's genital organs, including the vaginal vestibule.

Normal results

These microorganisms are not found in a normal culture. Many types of microorganisms, normally found on a person's skin and in the genitourinary tract, may contaminate the culture. If a mixture of these microorganisms grow in the culture, they are reported as normal flora.

Abnormal results

If a person has a positive culture for one or more of these microorganisms, treatment is started and his or her sexual partners should be notified and tested. Certain laws govern reporting and partner notification of various STDs. After treatment is completed, the person's physician may want a follow-up culture to confirm the infection is gone.

Resources

PERIODICALS

"Answer Back: Is there a Vulval Swwab Test for Chlamydia?" Pulse September 13, 2004: 100.

"Approval Sought for HIV-1 Test that Detects Antibodies in Oral Fluid or Plasma." AIDS Weekly October 27, 2003: 23.

Boschert, Sherry. "Chlaymdia Urine Test: Males Still Underscreened: Noninvasive Screening Test." Pediatric News August 2004: 10-12.

"FDA Approves DNAwithPap for Screening Women (Greater than or Equal to) Age 30)." Contemporary OB/Gyn October 2003: 105.

"FDA Approves OraQuick HIV-1/2 Test to Detect HIV-2 in Oral Fluid." Biotech Week July 21, 2004: 401.

Kaye, Donald. "FDA Approves Herpes Antibody Test." Clinical Infectious Diseases September 15, 2004: 1.

"New HIV Rapid Test Is 100 Percent Accurate." Health & Medicine Week September 15, 2003: 194.

"New Three-minute Rapid HIV Test Launched in the United States." Medical Devices & Surgical Technology Week September 12, 2004: 102.

"One-step HIV Test May Be Cheaper, Faster, Less Wasteful." Medical Letter on the CDC & FDA October 5, 2003: 5.

St. Lawrence, Janet S., et al. "STD Screening, Testing, Case Reporting, and Clinical and Partner Notification Practices: A National Survey of U.S. Physicians." The American Journal of Public Health November 2002: 1784.

ORGANIZATIONS

American Social Health Association. PO Box 13827, Research Triangle Park, NC 27709. (800) 227-8922. 〈http://sunsite.unc.edu/ASHA〉.

Centers for Disease Control and Prevention. National Center for HIV, STD, and TB Prevention. 1600 Clifton Road NE, Atlanta, GA 30333. (404) 639-8000. 〈http://www.cdc.gov/nchstp/od/nchstp.html〉.

sexually transmitted diseases were previously called ‘venereal diseases’, of which there were three: syphilis, gonorrhoea, and chancroid. Over time, but particularly during the second half of the twentieth century, the range of diseases spread by sexual contact have increased considerably, and include infection by a variety of organisms, particularly bacteria and viruses, of which the newest is the Human Immunodeficiency Virus, causing AIDS (see table).

Currently, the geographical distribution of the sexually transmitted diseases (STDs) varies in number and type of condition. The World Health Organisation (WHO) estimates 333 million new infections per year (excluding HIV/AIDS). The major focus is South and South-East Asia, with an estimated 150 million new cases in 1995, and sub-Saharan Africa, with 65 million. In the developing world, the commonest diseases are gonorrhoea, syphilis, chancroid, and HIV infection, whereas in developed countries they are chlamydial infections, non-specific urethritis, genital warts, and herpes.

The STDs are important because of their complications and social stigma. The most serious sequelae occur in women, and are pelvic inflammatory disease (infection in the fallopian tubes) and ectopic pregnancy (pregnancy in the tubes), but the infections also increase the risk of stillbirth and prematurity, and can affect the new-born baby. In sub-Saharan Africa, 50% of cases of infertility can be attributed to prior tubal infection, usually with gonorrhoea or chlamydia.

Microorganisms that can be sexually transmitted

The diseases and their features

The three most common presenting symptoms of STDs are urethral discharge, genital ulceration, and vaginal discharge. Whereas the first two are usually due to an STD, vaginal discharge is not. Most women have a physiological vaginal discharge, which can vary from day to day, and can also be related to their menstrual cycle. It can be due to other infections, such as candida (thrush), which are not usually sexually transmitted. Pointers to the possibility that a vaginal discharge is due to an STD are development of symptoms after a recent partner change, recent multiple sexual contacts, symptoms that are recurrent or persistent, and symptoms in the woman's partner. Finally, there may be general symptoms such as abdominal pain, menstrual problems, or pain on intercourse.

Gonorrhoea, non-specific genital infection, and chlamydia

In heterosexual men, these conditions give rise to discharge from the penis, 3–14 days after exposure. In homosexual men, the rectum can be infected, but in many incidences the patient is unaware of this unless they attend a clinic for a routine check-up, or at the request of a partner who develops symptoms. In women, these three conditions can often be without specific symptoms, especially since vaginal discharge is common. These infections are particularly important in women because of the complication of pelvic inflammatory disease; if this arises, it usually causes abdominal pain, perhaps with menstrual disturbances, and pain on intercourse. Women may only become aware of their infection when their male partner develops problems. Gonorrhoea can be treated with penicillin, and non-specific genital infection and chlamydia with tetracycline.

Genital warts

— small lumps around the genital regions — have become increasingly common. They have a very long incubation period after exposure (anything up to 6 months). Treatment is straightforward, by freezing or applying acidic substances such as podophyllin. Warts tend to recur. It is important that they are treated, particularly in women, where there is a possible association between some types of warts and the later development of carcinoma of the cervix. All women with genital warts should have regular cervical smears.

Genital herpes

is a viral condition with a short incubation period of approximately 3–7 days. If it is a first attack, the symptoms can be particularly severe, with pain, and blisters breaking down into sores, which sometimes can be extensive. Occasionally patients may have a temperature and headache, and feel generally unwell. There are two types of herpes simplex virus. Herpes type 1 normally causes cold sores, but oral–genital contact can transmit this from the lips to the genital area, therefore one should avoid this type of contact with people during the time that they have cold sores. There is no cure for this condition, and it tends to recur, but with unpredictable frequency from patient to patient. Pregnant women can pass herpes on to the baby at the time of delivery, so they should be under specialist care.

Syphilis

is now very uncommon in the UK. Primary syphilis occurs after an incubation period of about 9–90 days. Usually a solitary, painless ulcer appears at the site of exposure (penis, vulva, rectum, etc.). This will heal without treatment. Secondary syphilis appears 4–8 weeks later, in the form of a widespread rash, mainly on the shoulders, chest, back, abdomen, and arms. Tertiary syphilis occurs any time from 3–20 years after exposure, with complications affecting the central nervous system and heart.

Candidiasis, trichomonas, and bacterial vaginosis

cause vaginal discharge, and are not usually sexually transmitted.

Genital ulcers

are not necessarily due to STD. In Britain the commonest causes are genital herpes and syphilis, but in tropical countries there are other conditions commonly causing genital ulceration.

HIV and AIDS

Even though North America and Europe experienced the first impact of the AIDS epidemic, infections with HIV are now seen throughout the world, with the focus having switched to developing/resource-poor countries. WHO estimate that, by the end of 2000, 36.1 million people were living with HIV/AIDS, and that 5.3 million new infections occurred during that year. At the time of writing, 90% of all infections occur in developing countries and continents, with the major brunt of the epidemic in sub-Saharan Africa (22.5 million cases), and south and south-east Asia (6.7 million cases).

It is now realized that cases of AIDS were first seen in central Africa in the 1970s, even though at that time it was not recognized as such. Current surveys from some African countries show that the level of infection is high amongst certain groups: in 50–90% of prostitutes and 30% of those attending departments for STDs and antenatal clinics. The advent and increase of HIV infection since the 1980s has highlighted the importance of infections spread by the sexual route. It has also been recognized that the presence of a sexually transmitted disease, particularly (a) genital ulcer(s) and/or a vaginal/urethral discharge, can enhance both the acquisition and transmission of HIV by increased shedding of the virus within and from the genital tract.

The most common mode of transmission of this virus throughout the world is by sexual intercourse, vaginal or anal. Other methods of transmission are through the receipt of infected blood or blood products, semen, or donated organs; and through the sharing or re-use of contaminated needles by injecting drug users, or for therapeutic procedures. Also, transmission from mother to child can occur, in the womb, possibly at birth, or through breast milk.

Acute infection with HIV usually passes unnoticed, although there may sometimes be fever, swollen lymph nodes, muscular pain, and a rash. Most patients are unaware of their infection unless they are tested. The antibody test carried out on blood can take approximately three months to become positive (the window period). In view of this, patients are encouraged to delay being tested after possible exposure. Chronic infection follows and again the patient may not be aware that they are infected — or they may have non-specific symptoms such as fever, night sweats, diarrhoea, and weight loss. The time between infection with HIV and developing AIDS can be very long: on average about 8–9 years. Once a patient develops AIDS, they can have tumours and/or infections in various parts of the body. There is no cure for AIDS, but the infections can be treated, and new antiviral agents against HIV are now more powerful, and may alter the medical history and life expectancy of those infected.

Control of sexually transmitted diseases

is served in the UK by a network of specialist clinics: departments of Sexually Transmitted Diseases or Genitourinary Medicine clinics. The image of such clinics has changed considerably; they have become more friendly, with far less associated stigma. Most people attend without medical referral, and because the remit of these clinics has extended in recent decades, many use them for check-ups, screening for HIV, and for gynaecological problems or contraceptive advice. In developing countries, such specialist services do not usually exist, and sexually transmitted diseases are normally managed in non-specialist services, usually in rural primary health centres by non-medical staff.

Prevention of STDs involves primary and secondary approaches. Primary prevention aims to educate individuals about the advantages of discriminate and safe sex (prevention by the use of condoms), about the symptoms of the common sexually transmitted diseases, and about how to seek care for them. It is also important to point out that some conditions may cause no symptoms, so that regular check-ups are advised for those who often change their partners.

Secondary prevention aims to encourage people to seek care without delay once the symptoms of a disease are recognized, to stop sexual intercourse until medical advice has been sought, and to adhere to the advice and treatment given. The final aspect of control is the tracing of the sexual contacts of the infected patient, who may have infection without being aware of it.

M. W. Adler

Bibliography

Adler, M. W. (1980). The terrible peril — a historical perspective on the venereal diseases. British Medical Journal, 281, 206–11.
Adler, M. W. (1997). The ABC of AIDS, (4th edn). BMJ Publications, London.
Adler, M. W. (1999). The ABC of sexually transmitted diseases, (4th edn). BMJ Publications, London

Sexually Transmitted Diseases

A sexually transmitted disease (STD) is any disease whose primary (though not necessarily only) mode of transmission is some form of sexual contact. STDs may be viral, bacterial, protistan (protozoan), or fungal. Certain STDs, such as gonorrhea and syphilis, are classified as "reportable" because when diagnosed they must be reported to a proper health or government agency to prevent their spread.

Bacteria

Gonorrhea. Gonorrhea, one of the most widespread of the STDs, is caused by the bacterium Neisseria gonorrhoeae, some strains of which are resistant to treatment by penicillin as well as the other drugs of choice. The organism itself is quite fragile and cannot survive long enough outside the body to be transmitted from one person to another via infected toilet seats, clothing, or household utensils. It is readily killed by sunlight, drying, or ultraviolet light.

Although any mucous membrane may be affected, the usual gonorrheal infection is found in the genitourinary tract. In the female, the symptoms of gonorrhea are usually mild and may resemble a simple vaginal infection, or they may go completely unnoticed. If left untreated in females, the infection can cause a blockage of the fallopian tubes as well as other pelvic inflammatory diseases. Because of the permanent reproductive tract damage gonorrhea can cause it is often called the "great sterilizer."

In males, the organism often causes a painful infection of the urethra and if left untreated, a complete blockage of the urethra can occur. Other complications of gonorrhea may include damage to the kidneys, heart valves, and joints. The rectal area, conjunctiva , and oral mucosa may also be affected. Because infants can acquire gonorrhea of the conjunctiva while passing through the birth canal of an infected mother, the eyes of newborns are routinely treated with silver nitrate or a penicillin ointment.

Syphilis. Syphilis begins when the spirochete bacterium Treponema pallidum enters the body through a tiny break in the skin. The primary lesion, forming at the site of entry between ten and ninety days after infection, is called a chancre and it is teeming with the spirochetes. This chancre is also normally painless and thus may go undetected, particularly in females if it is high in the vagina. The chancre usually disappears, but the organisms disperse to various parts of the body. About six weeks later, secondary syphilis appears as a hypersensitivity reaction to the bacteria. Secondary syphilis is usually characterized by a generalized skin rash (including on the palms of the hands and the soles of the feet) and often by such flu-like symptoms as headache, fever, and general malaise.

In about half the cases, anywhere from several months to twenty or more years after the initial infection, syphilis progresses to the tertiary stage. (Of the remaining cases, about half appear to be cured, and the rest, while not cured, do not seem to progress to the tertiary stage.) Tertiary syphilis may be relatively mild, affecting only the bones or skin; or it may be serious or even fatal, affecting the cardiovascular system (causing such conditions as aortic aneurysms ) or the central nervous system (causing paralysis or syphilitic insanity). In congenital syphilis, the fetus acquires the disease prenatally; the chancre of primary syphilis is bypassed.

Syphilis is usually treated with penicillin, which is especially effective in primary and secondary cases. Other drugs can be used. Treating a pregnant woman also treats her child. As with the gonorrhea organism, Treponema pallidum is quite fragile and cannot survive long enough outside the body to be transmitted from one person to another via infected toilet seats, clothing, or household utensils.

EHRLICH, PAUL (1854–1915)

German physician who discovered an effective drug treatment for the sexually transmitted disease syphilis. Ehrlich's drug was the first example of a modern antibiotic, a substance that specifically kills disease-causing organisms without significantly hurting the patient. He won many awards and prizes, including the 1908 Nobel Prize in medicine.

Nongonococcal Urethritis (NGU). Nongonococcal urethritis is a categorical term for any of a number of inflammatory diseases of the sexual organs. By far the most frequently observed of the STDs is chlamydial NGU. Other chlamydial infections include trachoma, an eye disease, and possibly certain arterial plaques and other coronary artery diseases.

Chlamydial NGU. Chlamydial NGU, caused by the obligate intracellular bacterium Chlamydia trachomatis, is also a reportable STD. Chlamydial NGU is often a secondary infection following a gonorrheal infection. Although asymtomatic infections are common in both sexes, in males chlamydial NGU causes urethritis, and in females it causes urethritis, cervicitis, and pelvic inflammatory disease (PID). In serious cases, acute complications such as testicular or prostate swelling in males or the lysing of fallopian tube cells in females can occur.

Pelvic Inflammatory Disease. Pelvic inflammatory disease is a categorical term for any of several inflammations of the pelvic organs. The most common causative agents of PID are Chlamydia trachomatis and Neisseria gonorrhoeae. The specific drug of choice for treatment depends on the cause of the PID. PID is more commonly associated with females than with males. Untreated PIDs can be extremely serious. PID is a leading cause of sterility, particularly among females.

Lymphogranuloma Venereum (LGV). Lymphogranuloma venereumis caused by a specific strain of Chlamydia trachomatis and is one of the most serious of the chlamydial infections. This disease occurs more frequently in males and is characterized by swelling in the groin and in the lymph nodes. The bacteria may also cause proctitis (inflammation of the rectal tissues). Doxycyline is the drug of choice.

Viruses

Herpes. Herpes is a virus or family of viruses (the herpes viruses) causing cold sores, fever blisters, and genital infections. Herpes virus type I (HV1) was formerly thought of as causing problems "above the belt," while Herpes virus type 2 (HV2) has been credited with problems "below the belt." Today it is known that either HV1 or HV2 (including their many serotypes ) can infect any area of the body.

Genital (or anogenital) herpes results in painful blisters of the anus, penis (in males), and cervix, vulva , or vagina (in females). The disease, which can recur at sporadic intervals, is most contagious during the blister stage. Although the disease is incurable, it can be treated. Acyclovir is the drug of choice. Because genital herpes can be passed on through the birth canal, babies of pregnant women with this infection are often delivered by caesarian section. A significant correlation exists in females between genital herpes and cervical cancer.

Genital Warts. Genital warts are caused by a group of papilloma viruses. The presence of these warts in women has been associated with an increased risk of cervical cancer. Warts can be removed surgically, chemically, or by cryotherapy (freezing).

The Hepatitis Viruses. The hepatitis viruses, often identified today as A, B, C, D, and E, are not strictly STDs. However, hepatitis B and hepatitis C can be spread by sexual contact and hepatitis B can be spread in utero.

Protozoans and Yeast

HAZEN, ELIZABETH LEE (1885–1975)

U.S. biologist who, with Rachel Brown (1898–1980), developed the first fungicide. Nystatin is still used to treat dangerous oral and intestinal yeast infections. Hazen was orphaned at age two, attended the first state-supported college for women in the United States, and succeeded against great odds to become a biologist. Hazen and Brown donated all royalties from nystatin—worth more than $13 million—to academic science.

Trichomoniasis. Trichomoniasis is an NGU caused by the protozoan Trichomonas vaginalis. Although usually sexually transmitted, this disease is occasionally acquired from infected toilet or sauna seats, paper towels, or clothing. The organism infects the vagina and urethra of females and affected women experience vaginitis, vaginal discharge, and painful urination. In males the organism can infect the prostate, seminal vesicles , and urethra. The disease seems to be more prevalent among females than males, although males are more likely than females to be asymptomatic .

Candidiasis. Candidiasis, caused by the fungus (yeast) Candida albicans, is an opportunistic disease that often infects the vaginal tract, oral cavity, or respiratory system. The organism can also cause systemic tissue damage.

see also AIDS; Bacterial Cell; Bacterial Diseases; Birth Control; Female Reproductive System; Fungal Diseases; Male Reproductive System; Parasitic Diseases; Protozoan Diseases; Viral Diseases

Roberta M. Meehan

Bibliography

Berkow, R. The Merck Manual of Diagnosis and Therapy, 16th ed. Rahway, NJ: Merck Research Laboratories, 1992.

Carlson, K. J., S. A. Eisenstat, and T. Ziparyn. The Harvard Guide to Women's Health. Cambridge, MA: Harvard University Press, 1996.

Center for Disease Control, Division of Sexually Transmitted Diseases. <www.cdc.gov/nchstp/dstd/disease_info.htm>.

Madigan, Michael T., John M. Martinko, and Jack Parker. Brock Biology of Microorganisms, 9th ed. Upper Saddle River, NJ: Prentice Hall, 2000.

Sexually transmitted diseases

Long known as venereal disease, after Venus, the Roman goddess of love, sexually transmitted diseases (STDs) are among the most common infectious diseases in the world. (An infectious disease is one caused by a parasite that attacks a host and begins to multiply, interfering with the normal life functions of the host.) There are more than 20 known STDs, ranging from life-threatening to painful and unsightly.

While acquired immunodeficiency syndrome (AIDS) is the most widely publicized STD, others are more common. Chlamydia, gonorrhea, and genital warts are nearing epidemic rates in the United States. Other common STDs include genital herpes, trichomoniasis, and chancroid (pronounced KAN-kroyd). STDs are most prevalent among teenagers and young adults under the age of 25 and affect individuals of all backgrounds and socioeconomic levels. Some STDs are caused by bacteria and usually can be treated and cured. Others are caused by viruses and can typically be treated but not cured. Untreated STDs pose an enormous public health problem.

Bacterial STDs

STDs caused by bacteria include syphilis, gonorrhea, chlamydia, and chancroid. Syphilis is usually spread through sexual contact and begins with painless lesions (sores) called chancres (pronounced KAN-kerz) that may appear inside or outside the body. The disease occurs in four stages and eventually affects the entire body. It is curable with the antibiotic penicillin but if left untreated can result in blindness, insanity, or death.

Words to Know

Antibiotic: Drugs used to fight infections.

Bacteria: Single-celled microorganisms that live in soil, water, plants, and animals, and some of which are agents of disease.

Cervix: In females, the opening where the vagina meets the uterus.

Chancre: A sore that occurs in the first stage of syphilis at the place where the infection entered the body.

Epidemic: A rapidly spreading outbreak of a contagious disease.

Genitals: Organs of the reproductive system.

Infectious disease: A condition that results when a parasitic organism attacks a host and begins to multiply, interfering with the normal life functions of the host.

Urethra: The canal that carries urine from the bladder and serves as a genital duct.

Uterus: A pear-shaped, hollow muscular organ in which a fetus develops during pregnancy.

Vagina: In females, the muscular tube extending from the uterus to the outside of the body.

Virus: An infectious agent that can only reproduce in the cells of a living host.

Vulva: The external parts of the female genital organs.

Gonorrhea is a common infectious disease that often has no initial symptoms. It affects the urinary tract and reproductive organs in males and females and, if left untreated, can cause sterility and blindness. Chlamydia infection is the most common sexually transmitted disease in the United States. Symptoms of chlamydia are similar to those of gonorrhea, and the disease can result in sterility in both males and females if left untreated. Chancroid is a bacterial disease that is more common in males and is characterized by painful ulcers and inflamed lymph nodes in the groin. Syphilis, gonorrhea, chlamydia, and chancroid can all be successfully treated with antibiotics.

Viral STDs

Viral STDs include AIDS, genital herpes, and genital warts. AIDS is caused by the human immunodeficiency virus (HIV), which attacks the immune system, making the body susceptible to infections and rare

cancers. HIV is transmitted through the exchange of bodily fluids, such as semen, vaginal fluids, or blood. AIDS is a fatal disease in which a person usually dies from an infection that the body's damaged immune system cannot fight off.

Genital herpes is a widespread, recurrent viral infection caused by one of two types of herpes simplex virus. Herpes simplex virus type 1 most frequently causes cold sores of the lips or mouth. Herpes simplex virus type 2 causes painful blisters in the genital area (reproductive organs). After an initial painful infection that lasts about three weeks, recurring outbreaks of about ten days' duration may occur a few times a year.

Genital warts are caused by the human papillomavirus, of which there are more than 60 strains. After becoming infected with the virus through sexual contact, genital warts usually develop within two months. They may appear on the vulva, cervix, or vaginal wall of females and in the urethra or foreskin of the penis in males. The warts can be removed in various ways, but the virus remains in the body. Genital warts are associated with cancer of the cervix in females.

STDs caused by viruses cannot be cured. Currently, experimental AIDS and herpes vaccines are being tested with the hope that they will provide immunity against these diseases.

Other STDs

Other STDs include trichomoniasis, an infection caused by a parasitic protozoan that produces inflammation of the vagina and a badsmelling, foamy discharge in females. It can also infect the urinary tract of both males and females. Treatment consists of administration of a drug that kills the protozoa.

Prevention

The only sure way to prevent contracting an STD is through sexual abstinence. Other methods that can aid in prevention and spread of STDs include the use of condoms, knowledge of the physical signs and symptoms of disease, and having regular check-ups.

[See also AIDS (acquired immunodeficiency syndrome); Bacteria; Virus ]

SEXUALLY TRANSMITTED DISEASES

SEXUALLY TRANSMITTED DISEASES. Sexually transmitted diseases (STDs) are infections communicated between persons through sexual intercourse or other intimate sexual contact. In the early 1970s, as the number of recognized STDs grew, the World Health Organization adopted the term to supersede the five diseases that collectively had been called venereal diseases (VD), chancroid, gonorrhea, granuloma inguinal, lymphogranuloma venereum, and syphilis. More than sixty other infections of bacteria, protozoa, fungi, and viruses that can be transmitted sexually have been added to the designation.

Of the venereal diseases, gonorrhea and syphilis were the most prevalent in the United States before World War II. Because of the social stigma attached to the diseases and the difficulty in diagnosing them, statistics of their incidence are often unreliable when available at all. One 1901 study concluded that as many as eighty of every one hundred men in New York City suffered an infection of gonorrhea at some time. The same study reported 5 to 18 percent of all men had syphilitic infections. Progressive Era reformers and social critics pointed to the high incidence of venereal diseases and the moral and public health threats they posed to families and communities as evidence of a cultural crisis. Combating venereal diseases was an important component of the social hygiene movement during this period. The high rates of venereal diseases among military personnel also led the U.S. War Department to institute far-reaching anti-VD campaigns during World Wars I and II. Soldiers were told that VD, like the enemy on the battlefield, threatened not only their health but America's military strength.

The reform impulse that began during the Progressive Era and World War I subsided until the 1930s, when the U.S. Public Health Service renewed efforts against syphilis and gonorrhea, resulting in the 1938 passage of the National Venereal Disease Control Act. Disease control efforts in the 1930s included requiring mandatory premarital tests for VD in many states. Widespread disease testing and the introduction of penicillin in 1943 contributed to declining VD rates after World War II. But by the late 1950s the rates began a steady increase that persisted with liberal sexual attitudes in the 1960s and 1970s.

During the 1980s the global pandemic of acquired immune deficiency syndrome (AIDS) overshadowed other STDs. Between 1981 and 2000, 774,467 cases of AIDS were reported in the United States; 448,060 people

died of AIDS. Nearly 1 million other Americans were also infected by the human immunodeficiency virus (HIV), the virus that causes AIDS. The development of powerful antiretroviral therapies during the 1990s prolonged the lives of many Americans infected by HIV or suffering from AIDS.

In 2000, 65 million people in the United States were living with an incurable STD, and annually approximately 15 million new cases of STDs were diagnosed, of which nearly half were incurable. Of particular concern to public health officials was that nearly one-fourth of new STD infections occurred in teenagers. Also of concern was that STDs affected women and African Americans in disproportionately greater numbers and with more complications. The rates of gonorrhea and syphilis, for instance, were thirty times higher for African Americans than for whites. The most common STDs were bacterial vaginosis, chlamydia, gonorrhea, hepatitis B, herpes, human papillomavirus (hpv), syphilis, and trichomoniasis.

Incidence and prevalence vary dramatically from disease to disease. The incidence of some diseases, such as syphilis, reached a historic low in the late 1990s, while those of other diseases, such as chlamydia, genital herpes, and gonorrhea, continued to increase during the same period. STDs also pose an economic cost. The costs of the major STDs and their complications totaled almost $17 billion in 1994. With the emergence of antibiotic-resistant strains of once-treatable STDs, the problem has persisted as a major public health concern.

BIBLIOGRAPHY

Brandt, Allan M. No Magic Bullet: A Social History of Venereal Disease in the United States since 1880. New York: Oxford University Press, 1985.

National Center for HIV, STD, and TB Prevention, Division of Sexually Transmitted Diseases. Tracking the Hidden Epidemics, 2000: Trends in STDs in the United States. Atlanta: Centers for Disease Control and Prevention, 2001.

Poirier, Suzanne. Chicago's War on Syphilis, 1937–40: The Times, The Trib, and the Clap Doctor. Urbana: University of Illinois Press, 1995.

Shilts, Randy. And the Band Played On: Politics, People, and the AIDS Epidemic. New York: St. Martin's Press, 1987.

Smith, Raymond A., ed. Encyclopedia of AIDS: A Social, Political, Cultural, and Scientific Record of the HIV Epidemic. New York: Penguin, 2001.

D. GeorgeJoseph

See alsoSex Education .

sexually transmitted disease (STD) or venereal disease, term for infections acquired mainly through sexual contact. Five diseases were traditionally known as venereal diseases: gonorrhea , syphilis , and the less common granuloma inguinale, lymphogranuloma venereum, and chancroid. In the 1960s up to 20 other diseases were recognized as being transmitted by sexual contact, and the term "sexually transmitted disease" came into use. Some of the more common of these are AIDS , genital herpes (see herpes simplex ), chlamydia , and human papillomavirus . Other diseases or infestations that can be transmitted sexually include giardiasis , amebiasis, scabies , pubic "crab" lice (see louse ), hepatitis (A, B, and C), group B streptococcal infections (see streptococcus ), cytomegalovirus infection, and the protozoan infection trichomoniasis .

STDs are generally graver in women, in whom diagnosis is often more difficult and treatment less available than for men; untreated they can lead to infertility or cause miscarriage, premature birth, or infection of the newborn. In some instances two or more infections may be present concurrently. The spread of sexually transmitted AIDS increased dramatically during the 1980s and continued through the 1990s. Other STDs are often seen in tandem with AIDS, partly because open sores that they produce can provide an easy route for the AIDS virus to enter the body. In the 2007 it was estimated that 19 million new cases of STDs were contracted in the United States each year.

Granuloma inguinale is caused by Calymmatobacterium granulomatis and is common in tropical and subtropical regions. Early lesions appear as painless, red, open sores on the skin of the genital and pelvic regions, succeeded by a spreading ulceration of the tissues. If not treated, the condition becomes chronic and may lead to death through anemia and general debility. Antibiotics such as tetracycline can eliminate the infection.

Lymphogranuloma venereum, also common in tropical and subtropical regions, is caused by a strain of Chlamydia trachomatis, an organism classified as a bacterium but having some viral characteristics. The primary genital lesion is often overlooked. The lymphatic structures about the pelvic and rectal region then become involved; blockage of such structures may cause disfigurement and scarring of external genitals. Fever and headache are other constitutional symptoms. Severe involvement of the rectal mucosa may cause intestinal obstruction or stricture. Tetracycline is the drug of choice, although other antibiotics are effective.

Chancroid is an acute localized infection caused by a bacterium called Hemophilus ducreyi. It can result in painful ulcerations of the skin, usually in the groin. In women symptoms may be absent or limited to painful urination, defecation, or intercourse. Involvement of the lymph nodes occurs in more than half the cases. Usually the disease is self-limited, but it may cause severe destruction of tissue. Antibiotics have been effective in treatment, but resistant strains are an increasing problem.

In order to reduce ignorance and thereby decrease the risk of venereal infection, the U.S. government just before and after World War II encouraged publicity on the matter, for the taboo long associated with public discussion of these contagious diseases had given rise to serious public-health problems. A nationwide campaign was initiated in 1937 by Thomas Parran, then serving as U.S. surgeon general, to educate the public about the incidence, cause, and cure of venereal diseases. As a result, the number of new cases in the United States steadily declined each year until the 1950s, when a rise was noted, especially among teenagers and young adults. In 1998, concerned by high U.S. rates of such common STDs as human papillomavirus, genital herpes, and chlamydia, as well as local outbreaks of syphilis and gonorrhea, the Centers for Disease Control and Prevention began a new far-reaching campaign to combat STDs.

Public authorities and private agencies coordinate their efforts to identify and isolate promptly all sources of infection. Worldwide, despite advances in diagnosis and treatment, the incidence of STDs has continued to rise and has reached epidemic proportions in many countries. Among the factors believed responsible for increases are changes in sexual behavior (e.g., the use of oral contraceptives), the emergence of drug-resistant strains, symptomless carriers, a highly mobile population, lack of public education, and the reluctance of patients to seek treatment.

Bibliography: See T. Rosebury, Microbes and Morals (1971); K. L. Jones et al., VD (1974); J. Jacobson, Women's Reproductive Health (1991).

sexually transmitted diseases: a brief history Sexually transmitted diseases (STDs) have been known since antiquity: gonorrhoea was certainly described by the ancient Egyptians, and was recognized by Greek and Roman medical writers. The prevalence and spread of these diseases was exacerbated by war or other travel, and the rise of city dwelling, with the concomitant increase of people living in close proximity to each other. By the Middle Ages both gonorrhoea and syphilis were widespread. One view, by no means unchallenged, was that syphilis was brought to Europe by Christopher Columbus' sailors on their return from the New World. The differentiation of the 2 diseases from each other was often a matter of medical debate, from the sixteenth up until the nineteenth century, many authors believing that the symptoms of gonorrhoea (clap or gleet) were the early stages of syphilis (the pox). This view was substantiated by the British surgeon John Hunter (1728–93), who undertook heroic self-experimentation by injecting his own penis with material taken from a patient with gonorrhoea. On developing the signs of syphilis he concluded the two infections were the same — little realizing that his patient, like many others, actually suffered from both infections at the same time.

The main orthodox treatment for syphilis from the Middle Ages until the early years of the twentieth century consisted of the application of a mercury ointment, a favourite treatment for skin lesions. But sufferers from the disease were particularly susceptible to the blandishments of quacks and charlatans, and many successful businesses profited during the seventeenth through to the twentieth centuries from selling useless remedies.

In the middle of the nineteenth century a French physician, Philippe Ricord (1799–1889), convincingly demonstrated the differentiation of the two main STDs and determined the three stages — primary, secondary, and tertiary — of syphilis. Shortly afterwards Rudolph Virchow (1821–1902) established that syphilis was spread through the body by the blood, explaining the known cardiovascular, muscular, and psychiatric complications. At the turn of the twentieth century up to a third of inmates in mental asylums were reckoned to be suffering form tertiary syphilis.

During the nineteenth century an increasing number of public health measures, usually aimed at prostitutes, were taken to prevent or control the spread of STDs. The Contagious Disease Acts of Great Britain clearly tolerated prostitution, as they permitted, amongst other regulations, the compulsory examination and incarceration of infected women, often in the so-called Lock hospitals. A vociferous campaign was mounted by women's groups, civil rights activists, and members of the medical profession, and the Acts were repealed in 1886.

Advances against the diseases were notably improved by the discovery of their causative microorganisms. That of gonorrhoea was found in 1879 and that of syphilis in 1905. Shortly after this the German bacteriologist Paul Ehrlich (1854–1915) announced the efficacy of Salvarsan, an arsenic-based treatment for syphilis. Also a diagnostic test was devised, which was enormously important as it allowed the disease to be detected in sufferers not yet displaying the symptoms; they could then be advised on how to prevent or minimize passing on the infection. The development of the sulpha drugs and more potent antibiotics provided a wider range of effective drugs against these diseases. However, it rapidly became apparent that the provision of appropriate treatments did not eradicate these diseases, and that public health advice and personal hygiene education were also necessary. The appearance and world-wide spread of AIDS (Acquired Immune Deficiency Syndrome), for which an effective treatment is still unavailable, during the 1980s, has emphasized the complex nature of these diseases.

E. M. Tansey

Bibliography

Brandt, A. M. (1993). Sexually transmitted diseases. In Companion encyclopaedia of the history of medicine, (ed. W. F. Bynum and R. Porter), Vol. 1. Routledge, London.

Diseases, Sexually Transmitted. Venereal diseases, or as the military currently defines them, sexually transmitted diseases (STDs), occur most often in sexually active people less than twenty‐four years of age. Because military forces historically have consisted of mostly young people, predominantly young men, often sexually active, the incidence of STD in military personnel has always been two to three times that of a similar matched group of civilians. This rate can rise five to eight times higher during wartime.

Some form of STDs seems to have plagued military forces from earliest recorded history. Herodotus in the fifth century B.C.E. wrote that Scythian soldiers who pillaged the Celestial Temple of Venus were infected with a “female disease” that afflicted all of their descendants. The first recorded cases of syphilis appeared in Europe in 1493 supposedly among Spanish sailors returning from the New World. Spanish and French armies soon spread what was called the “Neapolitan disease” or the “French pox” throughout Europe.

Historically, two methods have been advocated for controlling rates of STDs in the U.S. military: punishment of soldiers and support for regulation of civilian conveyors of the disease through regular examination and treatment of prostitutes. Traditionally when rates became high, particularly in wartime, regulation was enforced; when rates returned to baseline levels, the military either ignored the problem or relied upon punitive action. Such shifts in policy occurred during the Civil War, the Spanish‐American War, and World War I. The primary reason was that the methods of treatment, which consisted chiefly of local applications of antiseptics (containing arsenic, mercury, and bismuth), were only marginally effective. In addition, infected soldiers often did not develop a persistent and immediately debilitating illness, although they often became asymptomatic and infectious carriers. During World War I, the military public health authorities sought to eliminate prostitution in the areas around U.S. military and naval bases.

During World War II, the public health authorities encouraged publicity about venereal disease, breaking a long taboo on public discussion. The advent of antibiotics, especially penicillin, had a dramatic impact on STDs, primarily gonorrhea and syphilis. Another effective preventive measure was the use of condoms, which were distributed to all members of the armed forces.

STDs reemerged as a major problem in the military in the 1960s and 1970s as a result of several new developments. In the wider society, the “sexual revolution” in attitudes and behavior meant that sexual encounters were more readily accepted as a social norm. There was also indiscriminate use of antibiotics, thus reducing their effectiveness. And in 1976, new resistant strains of gonorrhea emerged first in the Far East, then in the United States which within a decade rendered many antibiotic treatments useless. Further, new sexually‐transmitted viral agents emerged: herpes; venereal warts (Papilloma virus); hepatitis B; and the deadly AIDS virus, HIV.

STDs have always been a problem for the military. Attempts to control them by changing behavior have had a significant, if temporary, impact. But recent resistant microorganisms and new STDs threaten to bring back the high prevalence rate that existed before antibiotics.
[See also Casualties; Demography and War.]

Bibliography

U.S. Army, Medical Department , Preventive Medicine in World War II, Vol. V: Communicable Diseases, ed. John B. Coates, Ebbe C. Haff, and Phebe M. Hoff, 1960.
Stanhope Bayne‐Jones , The Evolution of Preventive Medicine in the United States Army, 1606–1939, 1968.
Edmund C. Tramont , AIDS and Its Impact on Medical Readiness, Military Review, 6 (1990), pp. 48–58.

Edmund C. Tramont

SEXUALLY TRANSMITTED DISEASES

DEFINITION

A sexually transmitted disease (STD) is a disease transmitted through sexual contact between two people. They may be transmitted through the exchange of semen, blood, and other body fluids or by direct body contact. The term sexually transmitted disease applies to more than twenty different infections. At one time, these diseases were more commonly referred to as venereal diseases.

DESCRIPTION

Sexually transmitted diseases are very common medical conditions. In the United States, about 85 percent of the most common infectious diseases can be spread by sexual contact. The rate of STD infection in the United States is more than 50 times as great as that in other developed countries. Experts estimate that 1 in 4 of all sexually active Americans will get an STD at least once in their lives.

About twelve million new STD infections occur in the United States each year with teenagers between the ages of sixteen and nineteen accounting for 1 in 4 cases.

Sexually transmitted diseases are often mild infections that can be cleared up with simple medical treatment. If left untreated, however, serious complications can result. These complications include:

• Birth defects
• Blindness
• Bone deformities
• Cancer
• Heart disease
• Infertility
• Mental retardation
• Death

The majority of these complications develop only when an STD is not treated properly.

Types of STD

The following are some of the more common STDs in the United States.

• Chlamydia. Chlamydial diseases are caused by microscopic organisms that belong to the family chlamydia (pronounced kluh-MID-ee-uh). Two common chlamydial infections are nongonococcal (not gonorrhea) urethritis (NGU) and nonspecific urethritis (NSU). Urethritis (pronounced YOOR-ih-THRY-tiss) means an inflammation of the urethra.
• Gonorrhea. Gonorrhea (pronounced gahn-uh-REE-uh) is caused by a microorganism called Neisseria gonorrhoea (pronounced ny-SEER-ee-uh gahn-UH-ree-uh). It is easily cured when treated properly.
• Genital warts. Genital warts are caused by the human papillomavirus (HPV). It is the single most important risk factor for cervical cancer in women (see cancer entry).
• Syphilis. Syphilis (SIF-uh-liss) is caused by a microorganism called Treponema pallidum (pronounced trep-uh-NEE-muh PAL-ee-um). Like most STDs, syphilis can be cured if treated promptly and correctly. However, when left untreated, it can cause serious damage to the body and even death.
• Human immunodeficiency virus (HIV) infection. HIV is the virus responsible for acquired immunodeficiency syndrome or AIDS (see AIDS entry). No cure is presently available for HIV infection. However, major steps have been made in finding ways to control the disease.

Sexually Transmitted Diseases: Words to Know

Antibiotic:

A substance derived from bacteria or other organisms that fights the growth of other bacteria or organisms.

Chlamydia :

A family of microorganisms that causes several types of sexually transmitted diseases in humans.

Condom:

A thin sheath (covering) worn over the penis during sexual activity to prevent pregnancy and the spread of STD.

Diaphragm:

A dome-shaped device used to cover the back of a woman's vagina to prevent pregnancy.

Gonorrhea:

An STD that affects the mucous membranes, particularly in the urinary tract and genital area. Can make urination painful and cause pus-like discharges through the urinary tract.

Lymph nodes:

Small round or oval bodies within the immune system. Lymph nodes provide materials that fight disease and help remove bacteria and other foreign material from the body.

Monogomy:

When both people in a relationship have no sexual activities outside of the relationship. The practice of having only one sexual partner.

Nongonococcal urethritis (NGU):

An inflammation of the urethra that is not caused by the microorganism that causes gonorrhea.

Nonspecific urethritis (NSU):

An inflammation of the urethra caused by a chlamydia microorganism. The term arose because at one time, the cause of the infection was not known.

Syphilis:

An STD that can cause sores and eventually lead to brain disease, paralysis, and death.

Semen:

A white fluid produced by the male reproductive system that carries sperm.

Vaccine:

A substance that causes the body's immune system to build up resistance to a particular disease.

CAUSES

STDs are transmitted during sexual activity. Sexual activity often involves the exchange of bodily fluids between two people. These bodily fluids include semen, blood, and saliva. The risk of contracting an STD is low in any sexual activity in which no bodily fluids are exchanged.

During sexual activity, the organisms that cause STDs are passed from an infected person to an uninfected person. Once those organisms enter the healthy person's body, they begin to grow and reproduce. After a certain period of time, enough organisms are present in the body to begin causing the symptoms of the disease.

The period after infection, during which the organisms are developing, is known as the incubation period. The incubation period varies widely for various STDs. For gonorrhea, NGU and NSU, the incubation may be as short as a few days. For HIV infections, the incubation period may be as long as ten years.

EHRLICH'S "MAGIC BULLET"

Syphilis is one of the most terrible diseases known to humans. When the organism that causes the disease (a spirochete ) enters the body, it produces relatively mild symptoms. The spirochete then goes into hibernation for many years. Later in the patient's life, the spirochete becomes active again. It then causes horrible symptoms. The patient may lose control of nervous and muscular functions, often accompanied by severe pain. Eventually severe mental disorders may develop, including insanity. The disease may also cause death.

A cure for syphilis was not available until the early twentieth century. It was found quite by accident. The German bacteriologist Paul Ehrlich was searching for a drug that would kill bacteria that cause disease. He called that drug his "magic bullet."

Ehrlich and his students organized their search for a "magic bullet" in a very systematic way. They made a list of all the chemical compounds they wanted to test. Then they tried each chemical on the list, one at a time.

In 1907, Ehrlich's team had reached compound #606. They found it had no effect on bacteria, so they set it aside. Two years later, one of Ehrlich's assistants decided to test compound #606 on spirochetes. He found that it killed them very effectively. A "magic bullet" for syphilis had been found!

The compound Ehrlich's team discovered contains the element arsenic. Arsenic is a powerful poison. The team named the compound salvarsan.

The symptoms of various STDs vary widely. In some cases, there may be no symptoms at all, but in most cases symptoms develop that are characteristic of a specific form of STD. Common symptoms of STDs include:

• In men, a discharge from the tip of the penis accompanied by pain while urinating
• In women, vaginal itching, burning, and odor, sometimes accompanied by bleeding not associated with menstruation

• In both men and women, swelling of lymph nodes in the groin
• In both men and women, skin rashes, sores, bumps, or blisters near the mouth, the genitals, or the anus
• Fever, chills, and other flu-like symptoms
• Aches and pains in the joints
• Swelling and redness in the throat that lasts for more than three weeks

DIAGNOSIS

The diagnosis of STDs depends to a large extent on the patient. Teenagers should learn the symptoms of various STDs. When they observe any of these symptoms in their own bodies, they should seek medical attention.

This principle is valuable advice for most diseases and disorders. But it is especially important in the case of STDs. People are often reluctant to talk about personal matters, such as sexual activity. They may prefer to ignore changes they observe in their genital areas or changes they know may be related to sexual activity. But timely treatment can stop STDs from becoming even more serious.

Most STDs are relatively easy to diagnose. The symptoms described above are easy to observe and quite characteristic of sexually transmitted diseases. Many of the diseases can be diagnosed with simple blood tests. The organism that causes the diseases can generally be detected and identified in the patient's blood.

Doctors often test for more than one STD at a time. A person who is infected with syphilis, for example, may also have gonorrhea at the same time.

Notification

Sexually transmitted diseases are regarded as a public health problem. That is, they do not involve a single person alone, but the health of the entire community. A person diagnosed with an STD was infected by someone else and is at risk of transmitting to others.

To cut down on the spread of STDs through a community, many states have reporting laws. These laws require that public health officials find and contact the partners of anyone diagnosed with an STD. The purpose of these laws is to reduce the spread of STDs through the community. In an ideal situation, patients themselves will contact all their partners. To make sure that happens, public health officials usually ask patients for the names and addresses of those partners. They then follow up with interviews to let those partners know that they may also be infected with an STD.

TREATMENT

All forms of STD should be treated by a medical professional. The type of treatment used differs from infection to infection. In some cases, antibiotics can cure a disease quickly and efficiently. (Antibiotics are substances derived from bacteria or other organisms that fight the growth of other bacteria or organisms.) The standard treatment for syphilis, gonorrhea, and chlamydial infections, for example, is a single injection of the common antibiotic penicillin or a series of pills.

Viral infections, like HIV infection and genital herpes, are more difficult to treat. There are not many effective medications for the treatment of viral infections.

PROGNOSIS

The prognosis for recovery from STDs varies from disease to disease. When properly treated in their earliest stages, many can be cured completely in a short period of time. Gonorrhea, NGU, NSU, and syphilis fall into this category.

In other cases, such as HIV infections, no cure is currently available. However, treatments are available to relieve the symptoms of non-curable STDs and to reduce the risk of serious complications.

PREVENTION

Sexually transmitted diseases can be prevented in a number of ways, including the use of vaccinations, lifestyle choices, safer sex practices, and hygienic measures.

Vaccines

Vaccines have been developed for a few STDs, such as hepatitis A and hepatitis B. A vaccine (pronounced vak-SEEN) is a material that that causes the body's immune system to build up resistance to a particular disease. Individuals at risk for these infections should be vaccinated against them. Researchers are continually looking for vaccines against other sexually transmitted diseases.

Lifestyle Choices

The risk of contracting a sexually transmitted disease is very much related to choices one makes about one's sexual activity. Abstinence (avoiding sexual activity altogether) may be the best method of avoiding STDs.

In general, the larger the number of sexual partners a person has, the greater the risk he or she has of contracting an STD. Among sexually active people, the risk of contracting an infection is lowest for those who are in monogamous (pronounced muh-NOG-uh-muss) relationships (couples who have no sexual partners outside of their relationship).

It is also important to know the health status of a prospective sexual partner. Sexual activity with prostitutes or anonymous partners increases the risk of contracting STD. Discussing one's sexual health with a prospective partner is an important health precaution.

One can also choose to take part or not take part in intravenous drug use. Intravenous drug use often involves sharing needles with other people who may be infected with an STD. Some sexually transmitted infections are easily spread in blood passed from one person to another.

Use of Condoms and Other Contraceptives

The term safer sex is used to describe a number of techniques that can be used during sexual activity to avoid contracting an STD. The concept is that sexual activity can be both pleasurable and safe by taking a few simple precautions.

Perhaps the most effective precaution one can use during sexual activity is a condom. When properly used, a condom is very effective in preventing the transmission of bodily fluids from one person to another.

Spermicides (substances that kill sperm) and diaphragms are also somewhat effective in preventing the spread of STDs. But they are not totally effective and do not prevent the spread of some organisms, such as HIV. Either or both of these, when used with a condom, can decrease the chance of spreading and STD.

Hygienic Measures

Cleanliness is always an important factor in avoiding the spread of any disease. However, careful washing alone is not very effective against most organisms that cause STDs. The organisms are often able to penetrate far up into the body, where they will not be affected by soap and water.

See also: AIDS, and Herpes infections.

FOR MORE INFORMATION

Books

Dudley, William, ed. Sexually Transmitted Diseases. San Diego: Greenhaven Press, 1999.

Marr, Lisa. Sexually Transmitted Diseases: A Physician Tells You What You Need to Know. Baltimore: Johns Hopkins University Press, 1999.

Woods, Samuel G., and Ruth C. Rosen, eds. Everything You Need to Know about STD. New York: Rosen Publishing Group, 1997.

Organizations

Planned Parenthood Federation of America. 810 Seventh Ave. New York, NY 10019 (800) 230–7526. http://www.plannedparenthood.org.

National STD Hotline. (800) 227–8922.

Web sites

"Ask NOAH About: Sexually Transmitted Diseases." NOAH: New York Online Access to Health. [Online] http://www.noah.cuny.edu/stds/stds.html (accessed on October 31, 1999).

"Basic Facts about STDs." [Online] http://www.mcare.org/healthtips/homecare/basicfac.htm (accessed on May 23, 1998).

"Can STDs Be Prevented?" [Online] http://housecall.orbisnews.com/sponsors/asfp/topics/infections_d/stds/page5.html (accessed on May 23, 1998).

"1998 Guidelines for Treatment of Sexually Transmitted Disease." [Online] http://www.cdc.gov/nchstp/dstd/STD98T03.htm (accessed on May 23, 1998).

"The Challenge of STD Prevention in the United States." [Online] http://www.cdc.gov/nch.stp.dstd/STD_Prevention_in_the_United_States.htm (accessed on May 23, 1998).

sexually transmitted disease (STD) Any disease that is passed from one individual to another during sexual intercourse or other types of sexual activity. These diseases have been traditionally referred to as venereal diseases. They include gonorrhoea, caused by the bacterium Neisseria gonorrhoeae; syphilis, due to infection by the bacterium Treponema pallidum; genital herpes, which is caused by a herpesvirus; and AIDS, resulting from infection with HIV, a retrovirus. The transmission of sexually transmitted diseases can be reduced by limiting the number of sexual partners and by the use of condoms (see birth control), which reduces the risk of contact with body fluids that harbour the microorganisms that cause these diseases.

Sexually Transmitted Diseases

What Are STDs?

How Common Are They?

Are STDs Contagious?

What Are Some Common STDs?

Can STDs Be Prevented?

Resources

Sexually transmitted diseases (STDs) are infections that pass from one person to another through sexual contact, which includes oral, genital, or anal intercourse.

KEYWORDS

for searching the Internet and other reference sources

Acquired immunodeficiency syndrome (AIDS)

Cervicitis

Chlamydia

Epididymitis

Genital warts

Gonorrhea

Herpes simplex virus

Human immunodeficiency virus (HIV)

Pelvic inflammatory disease

Prostatitis

Syphilis

Trichomoniasis

Urethritis

Vaginitis

What Are STDs?

STDs can be caused by bacteria, viruses, or parasites. Although the symptoms of a particular STD depend on the specific infection, many STDs cause vaginitis (vah-jih-NYE-tis), an inflammation of the vagina often accompanied by an abnormal discharge (fluid released from the body), and urethritis (yoo-ree-THRY-tis), an inflammation of the urethra (the tube through which urine passes from the bladder to the outside of the body), which can make urination painful. Several STDs can produce blisters or sores on the penis, vagina, rectum, or buttocks. In women, some STDs may spread to the cervix*, a condition called cervicitis (sir-vih-SYE-tis), or to the uterus* and fallopian tubes*, a condition known as pelvic inflammatory disease (PID). In men STDs may spread to the testicle (causing epididymitis*) or prostate* (causing prostatitis, inflammation of the prostate). It is not uncommon for several STDs to occur in the same person, and the presence of an STD can increase the risk of contracting infection with human immunodeficiency (ih-myoo-no-dih-FIH-shen-see) virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS), from an infected partner.

*cervix

(SIR-viks) is the lower, narrow end of the uterus that opens into the vagina.

*uterus

(YOO-teh-rus) is the muscular, pear-shaped internal organ in a woman where a baby develops until birth.

*fallopian

(fah-LO-pee-uhn) tubes are the two slender tubes that connect the ovaries and the uterus in females. They carry the ova, or eggs, from the ovaries to the uterus.

*epididymitis

(eh-pih-dih-duh-MY-tis) is a painful inflammation of the epididymis, a structure attached to the testicles.

*prostate

(PRAH-state) is a male reproductive gland located near where the bladder joins the urethra. The prostate produces the fluid part of semen.

How Common Are They?

STDs are common in the United States; between 13 million and 15 million new cases are diagnosed every year. Despite the fact that much information is available about preventing these infections and limiting their spread, the number of people infected is growing, and about two-thirds of cases are reported in people under the age of 25 years.

Are STDs Contagious?

STDs are contagious and are transmitted through sexual contact that involves vaginal, anal, or oral sex. The diseases can spread between people of the opposite sex or people of the same sex. The germs that cause many STDs move from person to person through semen (the sperm-containing whitish fluid produced by the male reproductive tract), vaginal (VAH-jih-nul) fluids, or blood. Other STDs, like herpes and genital warts, can spread by intimate skin-to-skin contact, often with sores the disease causes. Certain STDs can pass from a mother to her baby during pregnancy or childbirth. STDs do not pass from one person to another by simply hugging, shaking hands, or sharing utensils.

What Are Some Common STDs?

Gonorrhea

Gonorrhea (gah-nuh-REE-uh) is caused by the bacterium Neisseria gonorrhoeae (nye-SEER-e-uh gah-no-REE-eye). It may not produce any symptoms in women who are infected. When symptoms are present, they include vaginal discharge and pain when urinating. Lower belly pain usually occurs when the infection has spread past the cervix and caused PID. Most men with gonorrhea have a discharge from the penis and pain when they urinate. Gonorrhea is treated with antibiotics that kill the bacteria.

Syphilis

Syphilis (SIH-fih-lis) is caused by the bacterium Treponema pallidum (treh-puh-NEE-muh PAL-ih-dum). It is different from many other STDs, because there are distinct stages to the illness. In the first stage, a small, hard sore called a chancre (SHANG-ker) appears where the bacteria entered the body. In the next stage, a red or brown rash develops, sometimes on the palms of the hands and soles of the feet; in some cases, patients also may have a fever, swollen lymph nodes*, muscle aches, and headaches. If the disease goes untreated, it can progress to the third and most serious stage, when it may damage the bones, organs, and nervous system, which can result in blindness, paralysis*, dementia*, heart problems, and sometimes even death. Like gonorrhea, syphilis can be treated effectively with antibiotics. More than 31,000 cases of syphilis were reported in the United States in 2000.

*lymph

(LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.

*paralysis

(pah-RAH-luh-sis) is the loss or impairment of the ability to move some part of the body.

*dementia

(dih-MEN-sha) is a loss of mental abilities, including memory, understanding, and judgment.

Herpes simplex virus

Herpes simplex (HER-peez SIM-plex) virus causes herpes. There are two types of herpes, type1 and type 2. Type 2 usually spreads through sexual contact and causes genital herpes. In a person with genital herpes, small, painful blisters develop on the vagina, cervix, penis, buttocks, or thighs. Once infection occurs, the herpes virus remains in the body and can recur throughout a person’s life. Antiviral medications may shorten outbreaks of symptoms and make them less severe, but they do not kill the virus. In the United States an estimated 45 million people over the age of 12 have genital herpes infection.

Chlamydia

Chlamydia (kla-MIH-dee-uh) is caused by the bacterium Chlamydia trachomatis (kla-MIH-dee-uh truh-KO-mah-tis), and in many infected people it produces no symptoms. The most common symptoms in both men and women are discharge and pain when urinating. Because infection with chlamydia may not be noticed, it can spread and produce other symptoms, including epididymitis in men and PID in women. More than 700,000 cases were reported in the United States in 2000, but the actual number of new cases could be 3 million to 4 million per year. A person with chlamydia can be treated effectively with antibiotics.

HIV

Infection with HIV damages immune system cells in the body that normally fight infections, leaving the body unable to defend itself

against a variety of illnesses. A person can be infected with HIV and not have AIDS, although most people with HIV do end up developing AIDS. The first symptoms of HIV infection include fever, muscle aches, sore throat, and, in some cases, a rash that looks somewhat like that of measles*. Other symptoms usually take much longer to appear, perhaps years, and may include rapid weight loss, recurring fever, a dry cough, night sweats, pneumonia*, white spots on the tongue or throat, long-lasting diarrhea, and skin rashes and yeast infections. A person with AIDS also may have memory loss, depression, and extreme tiredness.

*measles

(ME-zuls) is a viral respiratory infection that is best known for the rash of large, flat, red blotches that appear on the arms, face, neck, and body.

*pneumonia

(nu-MO-nyah) is inflammation of the lung.

In the United States, there were more than 40,000 new cases of AIDS reported in 2000, and more than 850,000 people were living with HIV in 2000. There have been more than 460,000 reported deaths related to AIDS in the United States since the disease was first identified in the early 1980s. There is no cure for AIDS, but a combination of medications can help a person live longer and have a better quality of life.

Human papillomavirus

Genital and anal warts are caused by human papillomavirus (pah-pih-LO-mah-vy-rus), or HPV, a very common virus. The warts are soft and skin-colored, and they can grow alone or in bunches on the genitals; on the skin around the genitals, rectum, or buttocks; or in the vagina or cervix. Like herpes, genital warts can reappear again and again, because once this type of virus enters the body, it remains there for life. Doctors can remove genital warts by freezing, burning, or cutting them off or by coating them with medication that destroys the warts. In women, infection with HPV can affect the cells of the cervix, which may lead to cervical cancer.

Trichomoniasis

Trichomoniasis (trih-ko-mo-NYE-uh-sis) is a very common STD that is caused by a parasite. Most women with trichomoniasis have a frothy, yellow, foul-smelling vaginal discharge, along with itching and irritation in the vagina and discomfort during sex and urination. Men with this STD typically do not have symptoms; those who do have symptoms may feel irritation in the penis or a burning sensation after they urinate or ejaculate*. More than 2 million cases are diagnosed each year in the United States. Trichomoniasis can be treated with antibiotics.

*ejaculate

(e-JAH-kyoo-late) means to discharge semen from the penis.

Can STDs Be Prevented?

The only sure way to prevent STDs is not to have sexual contact with anyone. In most cases, it is impossible or very difficult to tell whether another person has an STD. People may not always tell the truth about their sexual past, or they may have an STD and not know it. For people who do have sex, the safest choices are to limit the number of sexual partners and to use latex condoms. Latex condoms lower the risk of contracting many STDs, including HIV infection. Certain STDs such as genital warts and herpes may present additional problems, because the warts or herpes blisters can be on the skin around the genitals and condoms do not protect against them if the sores are not covered by the condom. Avoiding skin-to-skin contact is the best option for preventing these kinds of STDs.

See also

AIDS and HIV Infection

Chlamydial Infections

Gonorrhea

Herpes Simplex Virus Infections

Syphilis

Trichomoniasis

Urinary Tract Infections

Warts

Resources

Organization

U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA 30333. The CDC provides fact sheets and other information on STDs at its website.

Telephone 800-311-3435 http://www.cdc.gov

Website

KidsHealth.org. KidsHealth is a website created by the medical experts of the Nemours Foundation and is devoted to issues of children’s health. It contains articles on a variety of health topics, including sexually transmitted diseases.

http://www.KidsHealth.org

sexually transmitted disease (STD) Any disease that is transmitted by sexual activity involving the transfer of body fluids. It encompasses a range of conditions that are spread primarily by sexual contact, although they may also be transmitted in other ways. These include acquired immune deficiency syndrome (AIDS), pelvic inflammatory disease, cervical cancer, and viral hepatitis. Older STDs, such as syphilis and gonorrhoea, remain significant public health problems.

sexually transmitted disease (STD) n. any disease transmitted by sexual intercourse, formerly known as venereal disease. STDs include AIDS, syphilis, gonorrhoea, genital herpes, Chlamydia infection, and soft sore. The medical specialty concerned with STDs is genitourinary medicine.
www.hpa.org.uk/infections/topics_az/hiv_and_sti/stidefault.htm Explanation of STDs from the Health Protection Agency