AIDS (Acquired Immunodeficiency Syndrome)

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AIDS (Acquired Immunodeficiency Syndrome)

Introduction

Disease History, Characteristics, and Transmission

Scope and Distribution

Treatment and Prevention

Impacts and Issues

Primary Source Connection

BIBLIOGRAPHY

Introduction

First reported in the United States in 1981, acquired immunodeficiency syndrome (AIDS, also cited as acquired immune deficiency syndrome) has since become a major worldwide pandemic. Medical research has demonstrated that AIDS is caused by HIV (the human immunodeficiency virus), a retrovirus, so named because its genes are coded in ribonucleic acid (RNA) instead of the more common deoxyribonucleic acid (DNA). Essentially, the virus causes disease by killing or damaging cells of the human immune system. HIV gradually destroys a person's ability to battle infections and certain types of cancer. This loss of immune system functioning causes victims to be vulnerable to often-deadly opportunistic infections, which are caused by pathogens (diseasecausing organisms) that are usually harmless to healthy people.

Because the spread of the AIDS epidemic in the United States has been extensively tracked and analyzed, the most reliable information regarding its transmission, treatment, and prevention comes from United States-based research. However, it should be understood that the vast majority of people infected with HIV now live outside of the United States. While modes of transmission of HIV have been determined to be the same across the world, risk patterns among different peoples have varied according to cultural influences. For example, outside of Western Europe and North America, homosexual activity has been comparatively more circumscribed and suppressed; hence the major pattern of sexual transmission of HIV occurs among heterosexuals in non-Westernized countries. Although the HIV epidemic acquired its original momentum in the United States, the future focuses of the pandemic lie outside of the United States, mainly in the developing countries of Africa and Asia.

Disease History, Characteristics, and Transmission

The most common way to transmit HIV is by having unprotected sex with an infected partner. The virus can enter the body through the mucous membranes of the vagina, vulva, penis, rectum, or mouth during sexual activity.

HIV is transmitted by the exchange of bodily fluids such as blood, semen, and saliva. Therefore certain behaviors put people at risk for contracting HIV, including sharing drug syringes, anal, vaginal or oral sexual contact with an infected person without using a condom, and having sexual contact with someone with unknown HIV status.

Contact with Infected Blood

It is possible to contract HIV through contact with infected blood. This risk has given rise to extensive screening of donated blood for evidence of HIV infection, and also heat-treatment techniques to destroy HIV in blood products used in medical practice. Prior to these measures, HIV was transmitted through transfusions of contaminated blood or blood products such as serum, platelets, and clotting factors. Screening for HIV and heat treatment has practically eliminated the risk of getting HIV from such transfusions.

Contaminated Needles

One of the primary means of spreading infection with HIV is the sharing of syringes contaminated with very small quantities of blood among injection drug users from someone that has been infected with the virus.

There have also been rare cases of health care workers that have been infected by accidental punctures with needles or other medical instruments that have been contaminated by contact with patients, or, conversely, patients that have been infected by contaminated needles used by health care workers. In the health care setting, workers have been infected with HIV after being stuck with needles containing HIV-infected blood or, less frequently, after infected blood gets into a worker's open cut or a mucous membrane (for example, the eyes or inside of the nose). According to the CDC, there has been only one instance of patients being infected by a health care worker in the United States; this involved HIV transmission from one infected dentist to six patients. Investigations have been completed involving more than 22,000 patients of 63 HIV-infected physicians, surgeons, and dentists, and no other cases of this type of transmission have been identified in the United States.

Mother-to-child Transmission

Women can transmit HIV to their babies during pregnancy or birth. About one-quarter to one-third of HIV-positive pregnant women will pass the virus on to their babies. HIV can also be transmitted from infected mothers to babies through breast milk. Available drug treatment for the mother during pregnancy can significantly reduce the probability of such infection. Cesarean section delivery can further reduce mother-to-newborn infection rates to just one percent. Drug treatment and cesarean delivery has nearly eradicated mother-to-baby transmission of HIV in the United States. Use of these measures has increased worldwide. A study in Uganda sponsored by the U.S. National Institute of Allergy and Infectious Diseases (NIAID) and confirmed by independent research has established the safety and effectiveness of an affordable drug treatment with nevirapine (NVP) for preventing mother-to-newborn transmission of HIV. A single oral dose of this antiretroviral drug given to an HIV-infected woman in labor and another to her baby within three days of birth reduces the transmission rate of HIV by 50%.

Saliva and Other Bodily Fluids

Researchers have detected HIV in the saliva of infected people. Nevertheless, no evidence has yet been produced that the virus is transmitted by contact with saliva. Laboratory studies indicate that saliva has natural properties that limit the infectivity of HIV, and the concentration of virus in saliva has been found to be very low. Studies of HIV-positive individuals have found no evidence that the virus can be spread through saliva by kissing. Because of the potential for contact with blood during open-mouth kissing, the CDC recommends against engaging in this activity with a person known to be infected with HIV. However, the risk of acquiring HIV during open-mouth kissing is considered to be very low. CDC has investigated only one case of HIV infection that may be attributed to contact with blood during open-mouth kissing. Nevertheless, the mucous membrane of the mouth can be infected by HIV, and there have been documented instances of HIV transmission through oral sex.

Researchers have found no evidence that HIV is spread through sweat, tears, urine, or feces that is not contaminated with blood.

Biting

In 1997, the CDC published findings from a state health department investigation of an incident that suggested blood-to-blood transmission of HIV by a human bite. There have been other reports in the medical literature in which HIV appeared to have been transmitted by a bite. Severe trauma with extensive tissue tearing and damage and presence of blood were reported in each of these instances. Biting is not a common way of transmitting HIV. In fact, there are numerous reports of bites that did not result in HIV infection.

Casual Contact and Environmental Transmission

Extensive studies of families of HIV-infected people have shown conclusively that HIV is not spread through casual contact such as the sharing of food utensils, towels and bedding, swimming pools, telephones, or toilet seats. HIV is not spread by biting insects such as mosquitoes or bedbugs.

From the beginning of the AIDS epidemic, some people feared that HIV might be transmitted in other common ways, but no scientific evidence to support these fears has been found. If HIV were being transmitted through other routes (such as through air, water, or by insects), the pattern of reported AIDS cases would be much different from what has been observed. For example, if mosquitoes could transmit HIV infection, many more young children and adolescents would have been diagnosed with AIDS. All reported cases suggesting new or potentially unknown routes of transmission are thoroughly investigated by state and local health departments with the assistance, guidance, and laboratory support from the CDC. No additional routes of transmission have been recorded, despite a national sentinel system (an early warning system using animals or population data to detect the presence of disease) designed to detect just such an occurrence.

Households

Although HIV has been transmitted between family members in a household setting, such transmission is very rare. These transmissions are argued to have resulted from contact between skin or mucous membranes and infected blood. To prevent even such rare occurrences, precautions should be taken in all settings including the home to prevent exposures to the blood of persons who are HIV infected, at risk for HIV infection, or whose infection and risk status are unknown. CDC guidelines stipulate that 1) gloves should be worn during contact with blood or other body fluids that could possibly contain visible blood, such as urine, feces, or vomit; 2) cuts, sores, or breaks on both the care giver's and the patient's exposed skin should be covered with bandages; 3) hands and other parts of the body should be washed immediately after contact with blood or other body fluids, and surfaces soiled with blood should be disinfected appropriately; 4) practices that increase the likelihood of blood contact, such as sharing of razors and toothbrushes should be avoided; needles and other sharp instruments should be used only when medically necessary and handled according to recommendations for health-care settings.

Businesses and Other Settings There is no known risk of HIV transmission to co-workers, clients, or consumers from contact in industries such as food-service establishments. Food-service workers known to be infected with HIV need not be restricted from work unless they have other infections or illnesses (such as diarrhea or hepatitis A) for which any food-service worker, regardless of HIV infection status, should be restricted. The CDC recommends that all food-service workers follow recommended standards and practices of good personal hygiene and food sanitation.

In 1985, CDC issued routine precautions that all personal-service workers (such as hairdressers, barbers, cosmetologists, and massage therapists) should follow, even though there is no evidence of transmission from a personal-service worker to a client or vice versa. Instruments that penetrate the skin (such as tattooing and acupuncture needles, ear piercing devices) should be used once and disposed of or thoroughly cleaned and sterilized. Instruments not intended to penetrate the skin, but which may become contaminated with blood (for example, razors) should be used for only one client and disposed of or thoroughly cleaned and disinfected after each use. Personal-service workers can use the same cleaning procedures that are recommended for health care institutions.

The CDC reports no instances of HIV transmission through tattooing or body piercing, although hepatitis B virus has been transmitted during some of these practices. One case of HIV transmission from acupuncture has been documented. Body piercing (other than ear piercing) is relatively new in the United States, and the medical complications for body piercing appear to be greater than for tattoos. Healing of piercings generally will take weeks, and sometimes even months, and the pierced tissue could conceivably be abraded (torn or cut) or inflamed even after healing. Therefore, a theoretical HIV transmission risk does exist if the unhealed or abraded tissues come into contact with an infected person's blood or other infectious body fluid. Additionally, HIV could be transmitted if instruments contaminated with blood are not sterilized or disinfected between clients.

Sexually Transmitted Infections

Sexually transmitted infections (STI) such as syphilis, genital herpes, chlamydia, gonorrhea, or bacterial vaginosis appear to increase susceptibility to infection with HIV during sex with infected partners.

In the United States, condoms are regulated by the Food and Drug Administration (FDA) and condom manufacturers are required to test each latex condom for defects such as holes prior to packaging. The proper and consistent use of latex or polyurethane condoms when engaging in vaginal, anal, or oral sexual intercourse can greatly reduce the risk of acquiring or transmitting sexually transmitted diseases, including HIV infection.

Only latex or polyurethane condoms provide a highly effective mechanical barrier to HIV. In laboratories, viruses occasionally have been shown to pass through natural membrane (“skin” or lambskin) condoms, which may contain natural pores and are therefore not recommended for disease prevention, although they are documented to be effective for contraception. For condoms to provide maximum protection, they must be used consistently and correctly. Numerous studies among sexually active people have demonstrated that a properly used latex condom provides a high degree of protection against a variety of sexually transmitted diseases, including HIV infection.

Early Signs and Symptoms of HIV Infection

Most people show no early symptoms when initially infected with HIV. In a minority of cases, people may have a flulike illness within a month or two after exposure that could include fever, headache, fatigue, and swollen lymph nodes in the neck and groin. These symptoms usually disappear within a week to a month and are often attributed to some other viral infection. During this early period, people are very contagious, and HIV is present in large quantities in genital fluids.

Long-lasting, debilitating symptoms may not appear for 10 or more years after infection with HIV in adults, or within 2 years in children born with HIV infection. This latent period without symptoms varies greatly by individual, ranging from a few months to more than a decade. However, even during the asymptomatic (without symptoms) period, the virus is actively multiplying and destroying immune system cells, or can be dormant (inactive) within infected cells. The most readily apparent laboratory sign of HIV infection is a gradual decline in the blood concentration of CD4 positive T (CD4+) cells, which are cells the immune system's most important infection fighters. HIV slowly disables or destroys these cells without causing symptoms.

As the immune system deteriorates, various complications appear. The first persistent symptoms experienced by many persons with HIV include enlarged lymph nodes for more than three months, fatigue, weight loss, frequent fevers and sweats, persistent or frequent yeast infections (oral or vaginal), persistent skin rashes or flaky skin, pelvic inflammatory disease in women that does not respond to treatment, and short-term memory loss. Some people develop frequent and severe herpes infections that cause mouth, genital, or anal sores, or a resurgence of the dormant virus that causes chickenpox known as shingles. Children may fail to thrive and grow.

Acquired Immunodeficiency Syndrome (AIDS)

Usually after a long assault on the immune system, victims reach the most advanced stage of HIV infection, which is known as AIDS. The CDC, the agency responsible for tracking the AIDS epidemic in the United States, has developed official criteria that define AIDS. The CDC's definition of AIDS includes all HIV-infected people who have fewer than 200 CD4+ T cells per cubic millimeter of blood. (Healthy adults usually have CD4+ T-cell counts of 1,000 or more.) In addition, the definition includes 26 clinical conditions, mainly opportunistic infections that affect people with advanced HIV disease. In people with AIDS, these infections are generally severe and can be fatal because the immune system is so ravaged by HIV that the body loses its ability to fight off certain bacteria, viruses, fungi, parasites, and other microbes.

Common symptoms of opportunistic infections in both adults and children with AIDS include persistent coughing and shortness of breath, seizures, lack of coordination, difficult or painful swallowing, confusion or forgetfulness, severe and persistent diarrhea, fever, vision loss, nausea, abdominal cramps, vomiting, weight loss, extreme fatigue, and severe headaches. In addition, children may also have severe forms of the common childhood bacterial infections, such as conjunctivitis (pink eye), otitis media (ear infection), and tonsillitis.

In addition to opportunistic infections, people with AIDS are also prone to various cancers that are associated with persistent exposure to certain viruses such as Kaposi's sarcoma and cervical cancer, or cancers of the immune system known as lymphomas. These cancers are usually more aggressive and difficult to treat in people with AIDS.

As HIV infection progresses and the number of CD4+ T cells declines, people with CD4+ Tcells above 200 may experience some of the early symptoms of HIV disease. Conversely, others with their CD4+ T-cell count below 200 may have no symptoms. Victims frequently become so debilitated by the symptoms of AIDS that they are unable to work or do household chores. Other persons with AIDS may experience intermittent phases of life-threatening illness followed by periods during which they appear to be reasonably healthy.

WORDS TO KNOW

ANTIBODY: Antibodies, or Y-shaped immunoglobulins, are proteins found in the blood that help to fight against foreign substances called antigens. Antigens, which are usually proteins or polysaccharides, stimulate the immune system to produce antibodies. The antibodies inactivate the antigen and help to remove it from the body. While antigens can be the source of infections from pathogenic bacteria and viruses, organic molecules detrimental to the body from internal or environmental sources also act as antigens. Genetic engineering and the use of various mutational mechanisms allow the construction of a vast array of antibodies (each with a unique genetic sequence).

ASYMPTOMATIC: A state in which an individual does not exhibit or experience symptoms of a disease.

CD4+ T CELLS: CD4 cells are a type of T cell found in the immune system, which are characterized by the presence of a CD4 antigen protein on their surface. These are the cells most often destroyed as a result of HIV infection.

HIGHLY ACTIVE ANTIRETROVIRAL THERAPY (HAART): Highly active antiretroviral therapy (HAART) is the name given to the combination of drugs given to people with human immunodeficiency virus (HIV) infection to slow or stop the progression of their condition to AIDS (acquired human immunodeficiency syndrome). HIV is a retrovirus and the various components of HAART block its replication by different mechanisms.

LATENT INFECTION: An infection already established in the body but not yet causing symptoms, or having ceased to cause symptoms after an active period, is a latent infection.

OPPORTUNISTIC INFECTION: An opportunistic infection is so named because it occurs in people whose immune systems are diminished or are not functioning normally; such infections are opportunistic insofar as the infectious agents take advantage of their hosts' compromised immune systems and invade to cause disease.

PANDEMIC: Pandemic, which means all the people, describes an epidemic that occurs in more than one country or population simultaneously.

REPLICATE: To replicate is to duplicate something or make a copy of it. All reproduction of living things depends on the replication of DNA molecules or, in a few cases, RNA molecules. Replication may be used to refer to the reproduction of entire viruses and other microorganisms.

RETROVIRUS: Retroviruses are viruses in which the genetic material consists of ribonucleic acid (RNA) instead of the usual deoxyribonucleic acid (DNA). Retroviruses produce an enzyme known as reverse transcriptase that can transform RNA into DNA, which can then be permanently integrated into the DNA of the infected host cells.

SEXUALLY TRANSMITTED DISEASE (STD): 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. More than 15 million new cases of STD are diagnosed annually in the United States.

SENTINEL: Sentinel surveillance is a method in epidemiology where a subset of the population is surveyed for the presence of communicable diseases. Also, a sentinel is an animal used to indicate the presence of a disease within an area.

STRAIN: A subclass or a specific genetic variation of an organism.

A few people known to have been infected with HIV ten or more years ago have not developed symptoms of AIDS. Scientists are trying to ascertain what factors may account for this lack of progression to AIDS, such as whether their immune systems have particular characteristics, whether they were infected with a less aggressive strain of the virus or whether their genes may protect them from the effects of HIV. Researchers hope that understanding the body's natural method of controlling infection may produce ideas for protective HIV vaccines that can prevent the disease from progressing in the general population.

Diagnosis

Because early HIV infection often causes no symptoms, health care providers can usually diagnose it by testing blood for the presence of antibodies (disease-fighting proteins) to HIV. HIV antibodies generally do not reach noticeable levels in standard blood tests in the blood for one to three months or more following infection. In order to determine whether a person has been recently infected, health care providers can screen for the presence of HIV genetic material. Such direct screening of HIV is extremely critical in order to prevent transmission of HIV from recently infected individuals. Such individuals can discuss with health care providers when they should start treatment to help combat HIV and prevent the emergence of opportunistic infections. Early testing also alerts people to avoid high-risk behaviors that could transmit the virus to others. Health care providers often provide counseling to individuals who test HIV positive. People can be tested anonymously at many sites if they are concerned about confidentiality.

The diagnosis of HIV infection is established by using two different types of antibody tests: ELISA and Western Blot. Individuals who are highly likely to be infected with HIV, but have received negative results for both tests may request additional tests or may be told to repeat antibody testing at a later date, when antibodies are more likely to have developed.

Babies born to HIV infected mothers may or may not be infected with the virus, but all carry their mothers' antibodies to HIV for several months. If these babies lack symptoms, a doctor cannot make a definitive diagnosis of HIV infection using standard antibody tests. New technologies have been developed to more accurately determine HIV infection in infants between ages 3–15 months. Researchers are evaluating a number of blood tests to determine which ones can best diagnose HIV infection in infants younger than three months.

IN CONTEXT: CULTURAL CONNECTIONS

Following the discovery of AIDS, scientists attempted to identify the virus that causes the disease. In 1983–84, two scientists and their teams reported isolating HIV, the virus that causes AIDS. One was French immunologist Luc Montagnier (1932–), working at the Pasteur Institute in Paris, and the other was American immunologist Robert Gallo (1937–) at the National Cancer Institute in Bethesda, Maryland. Both identified HIV as the cause of AIDS and showed the pathogen to be a retrovirus, meaning that its genetic material is RNA, instead of DNA. Following the discovery, a dispute ensued over who made the initial discovery, but today Gallo and Montagnier are credited as co-discoverers.

Scope and Distribution

Since 1981, more than 900,000 cases of AIDS have been reported in the United States. At least as many Americans may be infected with HIV, 25% of whom are not yet aware of their infection. AIDS has been spreading most rapidly among non-Caucasian populations and is one of the foremost killers of adult African-American males between the ages 25–44. The CDC has produced statistics showing that AIDS affects nearly seven times more African-Americans and three times more Hispanics than whites in the United States.

Worldwide, the AIDS epidemic has killed more than 25 million people since 1981, and an estimated 40 million people are living with AIDS today. Young people, under 25 years old, now account for more than half of all new HIV infections.

Treatment and Prevention

When AIDS first appeared in the United States, there were no medicines that were effective against HIV and few treatments existed for the associated opportunistic diseases. Within a relatively short time after the discovery of HIV, researchers began to develop drugs to fight both HIV infection and its associated infections and cancers.

The first group of drugs used to treat HIV infection, called nucleoside reverse transcriptase (RT) inhibitors, interruptsan early stage of the virus as it replicates (duplicates). These drugs slow the spread of HIV in the body and delay the start of opportunistic infections. This class of drugs, called nucleoside analogs, includes AZT (azidothymidine), ddC (zalcitabine), ddI (dideoxyinosine), d4T (stavudine), 3TC (lamivudine), abacavir, tenofovir, and emtricitabine.

Physicians can also prescribe non-nucleoside reverse transcriptase inhibitors (NNRTIs) to treat HIV infection, such as delavridine, nevirapine, and efravirenz, often in combination with other antiretroviral drugs.

A second class of drugs for treating HIV infection called protease inhibitors was later approved. Protease inhibitors interrupt the virus from replicating itself at a later step in its life cycle. They include ritonavir, saquinivir, indinavir, amprenivir, nelfinavir, lopinavir, atazanavir, and fosamprenavir.

A third new class of drugs known as HIV fusion inhibitors includes enfuvirtide, the first approved fusion inhibitor, which works by interfering with HIV-1's ability to enter into cells by blocking the merging of the virus with the cell membranes. This inhibition blocks HIV's ability to enter and infect the human immune cells. Enfuvirtide is designed for use in combination with other anti-HIV treatments. It reduces the level of HIV infection in the blood and may be active against HIV that has become resistant to current antiviral treatment schedules.

IN CONTEXT: TRENDS AND STATISTICS

The list below reflects data on the percentage (%) of all deaths in children under 5 years of age due to HIV/AIDS as reported by World Health Organization in February 2007.

Data is shown for countries reporting approximately that 4% or more of children under 5 years of age die from AIDS/HIV

Burkina Faso: 4.00%
Chad: 4.06%
Trinidad and Tobago: 4.69%
Ukraine: 4.95%
Nigeria: 4.96%
Rwanda: 4.99%
Bahamas: 5.34%
Côte d'Ivoire: 5.59%
Ghana: 5.74%
Togo: 5.78%
Jamaica: 6.09%
Thailand: 6.18%
Eritrea: 6.21%
Honduras: 6.28%
Cameroon: 7.24%
Equatorial Guinea: 7.39%
Uganda: 7.67%
Guyana: 7.68%
Burundi: 8.00%
Haiti: 8.28%
United Republic of Tanzania: 9.29%
Congo: 9.33%
Gabon: 10.10%
Central African Republic: 12.40%
Mozambique: 12.94%
Malawi: 14.04%
Kenya: 14.57%
Zambia: 16.12%
Zimbabwe: 40.59%
Swaziland: 47.00%
Namibia: 52.96%
Botswana: 53.85%
Lesotho: 56.19%
South Africa: 57.08%

SOURCE: World Health Organization

Because HIV can become resistant to any of these drugs, health care providers must use a combination treatment to effectively suppress the virus. When multiple drugs (three or more) are used in combination, it is referred to as highly active antiretroviral therapy, or HAART, and can be used by people who are newly infected with HIV as well as people with AIDS. Researchers have credited HAART as being a major factor in significantly reducing the number of deaths from AIDS in the U.S. While HAART is not a cure for AIDS, it has greatly improved the health of many people with AIDS and reduces the amount of virus circulating in the blood to nearly undetectable levels. Researchers, however, have shown that HIV remains present in some places in the body, such as the lymph nodes, brain, testes, and retina of the eye, even in people who have been treated.

Opportunistic Infections A number of available drugs help treat the opportunistic infections of AIDS. These drugs include foscarnet and ganciclovir to treat CMV (cytomegalovirus) eye infections, fluconazole to treat yeast and other fungal infections, and TMP/SMX (trimethoprim/sulfamethoxazole) or pentamidine to treat a pneumonia known as PCP (Pneumocystis carinii pneumonia) that is sometimes associated with AIDS.

Cancers Health care providers use radiation, chemotherapy, or injections of alpha interferon, a genetically engineered protein that occurs naturally in the human body, to treat Kaposi's sarcoma or other cancers associated with HIV infection.

Prevention

In the absence of a vaccine for HIV, the only means to prevent infection by the virus is to avoid behaviors that put people at risk of infection, such as sharing needles and having unprotected sex. Because many people infected with HIV have no symptoms, there is no way of knowing with certainty whether a sexual partner is infected unless he or she has repeatedly tested negative for the virus and has not engaged in any risky behavior. Abstaining from having sex offers the most protection from AIDS. Using male latex condoms or female polyurethane condoms have been shown in prospective studies to offer partial protection during oral, anal, or vaginal sex. Only water-based lubricants should be used with male latex condoms.

Although some laboratory evidence shows that spermicides can kill HIV, researchers have not found that these products can prevent the transmission of HIV during sex.

Ongoing Research

Research is ongoing in all areas of HIV infection, including developing and testing preventive HIV vaccines and new treatments for HIV infection and AIDS-associated opportunistic infections. Researchers also are trying to determine exactly how HIV damages the immune system. Recently, an electron micrograph was taken of HIV binding to a cell wall and is being examined for precise information about how the virus infects healthy cells. Such research is identifying new and more effective targets for drugs and vaccines. Investigators also continue to trace how the disease progresses in different people.

Current research also includes testing chemical barriers, such as topical microbicides (germ-killing compounds) that people can use in the vagina or in the rectum during sex to help prevent HIV transmission. Scientists are also examining the effectiveness of other ways of preventing HIV transmission, such controlling other sexually transmitted infections like chlamydia that have a role in making HIV easier to contract.

IN CONTEXT: ANTIRETROVIRAL THERAPY COVERAGE

The list below reflects selected data on antiretroviral therapy coverage from countries selected across the spectrum of data (ranked lowest to highest in terms of percentage of those estimated to need antiretroviral therapy who have actual access to the treatment) as reported by the World Health Organization in February 2007.

Selected non-reporting countries, or countries for which data was otherwise not available, included the Republic of Korea, Singapore, Afghanistan, and Iraq.

Sudan: 1% of persons estimated to need ARV therapy have access to the treatment (data reported: Dec 2005)
Nepal: 1% (Dec 2005)
Bangladesh: 1% (Dec 2005)
Somalia: 1% (Dec 2005)
Guinea-Bissau: 1% (Dec 2005)
Pakistan: 2% (Dec 2005)
Sierra Leone: 2% (Dec 2005)
Central African Republic: 3% (Dec 2005)
Philippines: 5% (Dec 2005)
Russian Federation: 5% (Dec 2005)
Belarus: 5% (Dec 2005)
Nigeria: 6% (Dec 2005)
Angola: 6% (Dec 2005)
Sri Lanka: 6% (Dec 2005)
Ukraine: 6 % (Dec 2005)
India: 7% (Dec 2005)
United Republic of Tanzania: 7 % (Dec 2005)
Ghana: 7% (Dec 2005)
Ethiopia: 7% (Dec 2005)
Myanmar: 7% (Dec 2005)
Zimbabwe: 8% (Dec 2005)
Mozambique: 9% (Dec 2005)
Gambia: 9% (Dec 2005)
Turkey: 9% (Dec 2005)
Iran (Islamic Republic of): 9% (Dec 2005)
Egypt: 12% (Dec 2005)
Viet Nam: 12% (Dec 2005)
South Africa: 21% (Dec 2005)
Kenya: 24% (Dec 2005)
China: 25% (Dec 2005)
Swaziland: 31% (Dec 2005)
Tunisia: 34% (Dec 2005)
Cambodia: 36% (Dec 2005)
Rwanda: 39% (Dec 2005)
Guatemala: 43% (Dec 2005)
Colombia: 44% (Dec 2005)
Senegal: 47% (Dec 2005)
Guyana: 50% (Dec 2005)
Uganda: 51% (Dec 2005)
Mexico: 71% (Dec 2005)
Canada: 75% (Dec 2005)
Israel: 75% (Dec 2005)
Italy: 75% (Dec 2005)
New Zealand: 75% (Dec 2005)
United Kingdom: 75% (Dec 2005)
United States of America: 75% (Dec 2005)
Costa Rica: 80% (Dec 2005)
Argentina: 81% (Dec 2005)
Brazil: 83% (Dec 2005)
Venezuela (Bolivarian Republic of): 84% (Dec 2005)
Botswana: 85% (Dec 2005)
Cuba: 100% (Dec 2005)

SOURCE: World Health Organization, Progress on global access to HIV anti-retroviral therapy. A report on “3 by 5” and beyond. Geneva, World Health Organization and Joint United Nations Programme on HIV/AIDS, March 2006.

Impacts and Issues

As the AIDS pandemic nears its 30th year, the number of people infected with HIV continues to climb steadily. Approximately two thirds of infected persons live in Africa, where the epidemic grew exponentially during the decade of the 1990s, and one fifth are in Asia, where the epidemic has been growing most rapidly in recent years. By the end of 2006, more than 40 million people worldwide were living with HIV infection. Worldwide funding from public and private sources to combat the epidemic has similarly risen dramatically, in an increasingly urgent effort to reverse the growth trajectory of the epidemic. Recent estimates of worldwide HIV infections and deaths have been revised downward, but these downward revisions do not reflect the uncertainty and unreliability of global HIV statistics outside of the major industrial nations.

Analysis of the reliable data has shown that the primary modes of HIV transmission have not changed significantly over time from those outlined above: unprotected heterosexual intercourse, unprotected anal sex between men, injection-drug use, unsafe medical injections and blood transfusions, and transmission from mother to child during pregnancy, labor and delivery, or breast-feeding. Direct blood contact, such as the sharing of drug-injection equipment, is by far the most efficient means of transmitting the virus. However the specific features of the epidemic vary among regions and within countries. Globally, in the World Health Report 2004, the World Health Organization (WHO) states that “unprotected sexual intercourse between men and women is the predominant mode of transmission of the virus.” This report also states that “In sub-Saharan Africa and the Caribbean, women are at least as likely as men to become infected.” In India, a large proportion of infected persons are prostitutes and long-haul truck drivers. In areas of China, India, Thailand, and Vietnam, HIV transmission is being fueled primarily by injection-drug use. In other parts of Southeast Asia, Cambodia, Myanmar, Thailand, and Vietnam, men having sex with prostitutes are a major factor.

IN CONTEXT: DISEASE IN DEVELOPING NATIONS

The World Health Organization (WHO) states that “in the developing world, 6 million people infected with HIV need access to antiretroviral (ARV) therapy. Only 300,000 have such access. To address the HIV/AIDS crisis, the World Health Organization, with the Joint United Nations Programme on AIDS (UNAIDS) and other partners, has committed itself to having 3 million people living with HIV/AIDS in developing countries on ARV treatment by the end of 2005.”

SOURCE: World Health Organization

The most recent statistics underline global disparities in AIDS deaths. Absent treatment with antiretroviral drugs, it usually takes about 10 years for HIV infection to progress to AIDS. More than two million people in sub-Saharan Africa died of AIDS in 2006 (accounting for three-quarters of the worldwide total). By comparison, in Western Europe, where drug treatment is widely available, only a few thousand people died of AIDS. In the most recent year of statistics, more than 12 million children in sub-Saharan Africa were orphaned by AIDS. Because the rapid growth of the epidemic is more recent in Asia, the number of deaths from AIDS has been comparatively lower than in Africa, given the number of infected people and a similar lack of drug treatment. Still, tens of thousands of people have died in Thailand and China each year in the past several years and death rates are increasing as asymptomatic infections acquired in the past decade progress to full-blown AIDS. Sub-Saharan Africa continues to have the most mother-to-child transmission of the virus, where more than a half-million children died of AIDS in 2005.

Increasingly the mantra of the international community is access for all to effective antiretroviral therapy. Only two approaches to containing the epidemic have been effective: preventing new HIV infections and providing antiretroviral treatment to victims of HIV. As there is no AIDS vaccine, prevention efforts focus on education about sexual and other practices, behavioral change, and outreach to marginalized groups of people, including injection-drug users and sex workers and their clients. Many infected people do not realize that they are infected; others may not seek available care because of the stigma of being HIV positive. Cambodia and Thailand are cited as examples of nations that have prevention programs promoting increased condom use by prostitutes and their clients that have been demonstrably effective.

Even if ambitious WHO goals for increasing access to antiretroviral treatment are successful, and despite substantial progress toward these goals, less than 10 percent of the people globally that need treatment for HIV infection are receiving it. A few countries such as Botswana, Senegal, and Uganda in Africa, and Brazil in South America are doing better. Brazil has a universal program for the distributing antiretroviral medications. Botswana, with one of the highest HIV infection rates in the world, has a program of routine HIV testing and is also successfully expanding access to drug treatment.

In summary, there is some evidence that the global HIV epidemic is starting to slow slightly, both in the rate of new infections and in the AIDS death rate. Behavioral change based on detailed knowledge of the means of viral transmission has been successful in saving millions of lives, and access to modern drug therapy has and can save millions more. Although the ultimate eradication of HIV infection remains a cherished goal of the worldwide medical research community, efforts to change behavior and expand access to currently available treatments will save untold millions of lives until the enigma of HIV infection is finally solved.

Primary Source Connection

In the commentary that follows, Nicholas D. Kristof describes the failures of political and health policies during the first quarter century of the AIDS pandemic in the context of family impacts in Swaziland. At the time of publication, Nicholas D. Kristof served as a columnist for the The New York Times since November 2001. In 1990, Kristof shared a Pulitzer Prize for coverage of China's Tiananmen Square uprising and democracy movement. In 2006, Mr. Kristof won a second Pulitzer for commentary.

BIBLIOGRAPHY

Books

Johanson, Paula. HIV and AIDS (Coping in a Changing World). New York: Rosen, 2007.

World Health Organization. Preventing HIV/AIDS in Young People. Geneva: WHO, 2006.

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Steinbrook R. Global Health: The AIDS Epidemic in 2004. New England Journal of Medicine 2004; 351:115–117, Jul 8, 2004.

Steinbrook R. HIV in India—The Challenges Ahead. New England Journal of Medicine 2007; 356: 1197–1201, Mar 22, 2007.

Steinbrook R. HIV in India—A Complex Epidemic. New England Journal of Medicine 2007; 356: 1089–1093, Mar 15, 2007.

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AIDS info. <http://aidsinfo.nih.gov> (accessed April 9, 2007).

NIH Vaccine Research Center. “Become an HIV Vaccine Study Volunteer.” <http://www.niaid.nih.gov/vrc/clintrials/clin_steps.htm%20%20%20> (accessed April 9, 2007).

Kenneth T. LaPensee

Infectious Diseases: In Context