Chickenpox
Chickenpox
Chickenpox and environmental factors
Chickenpox, a disease characterized by skin lesions and low-grade fever, is common in the United States and other countries located in areas with temperate climates. Until recently, the incidence of chickenpox was extremely high, and almost everyone living in the United States contracted chickenpox, usually during childhood. A chickenpox vaccine became available in 1995 and is now receiving widespread use. The annual case rate was reduced from about four million cases per year in the U.S to less than one million by the year 2000.
A highly contagious disease, chickenpox is caused by varicella-zoster virus (VZV), the same virus that causes the skin disease shingles. For most cases of chickenpox, no treatment besides pain relief and management of itching is necessary. In some cases, however, chickenpox may evolve into more serious conditions, such as bacterial infection of the skin lesions or pneumonia. These complications tend to occur in persons with weakened immune systems, such as children receiving chemotherapy for cancer or people with acquired immune deficiency syndrome (AIDS).
Despite its name, chickenpox has nothing to do with chickens. Its name has two possible origins. Some think that “chicken” comes from the French word chiche (chickpea) because at one stage of the disease, the lesions do indeed resemble chickpeas. Others think that “chicken” may have evolved from the Old English word gigan (to itch). Interestingly, the term “varicella” is a diminutive form of the term “variola,” the Latin term for smallpox. Although both chickenpox and smallpox are viral diseases that cause skin lesions, small-poxismoredeadlyanditslesions cause severe scarring.
Symptoms of chickenpox
Chickenpox is spread by breathing in respiratory droplets spread through the air by a cough or sneeze of an infected individual. Contact with the fluid from skin lesions can also spread the virus. The incubation period—or the time from exposure to VZV to the onset of the disease—is about 14-15 days. The most contagious period is just prior to the appearance of the rash, and early in the illness when fresh pox are still appearing. The first sign of chickenpox in children is often the appearance of the chickenpox rash. Adults and some children may have a prodrome, or series of warning symptoms. This precursor is typical of the flu, and includes headache, fatigue, backache, and a fever. The onset of the rash is quite rapid. First, small red “dots” appear on the skin. Soon, a vesicle containing clear fluid appears in the center of the dot. This small, reddish bump with a central clear fluid is sometimes referred to as “dewdrop on a rose petal” appearance. The vesicle rapidly dries, forming a crust. This cycle, from the appearance of the dot to the formation of the crust, can take place within eight to 12 hours. As the crust dries, it falls off, leaving a slight depression that eventually recedes.
Over the course of a case of chickenpox, an individual may develop between 250 and 500 skin lesions. The lesions occur in waves, with the first set of lesions drying up just as successive waves appear. The waves appear over two to four days. The entire disease runs its course in about a week, but the lesions continue to heal for about two to three weeks. The lesions first appear on the scalp and trunk. Most of the lesions in chickenpox are found at the center of the body; few lesions form on the soles and palms. Lesions are also found on the mucous membranes, such as the respiratory tract, the gastrointestinal tract, and the urogenital tract. Researchers think that the lesions on the respiratory tract may help transmit the disease. If a person with respiratory lesions coughs, they may spray some of the vesicle fluid into the atmosphere to be breathed by other susceptible persons.
Although the lesions look serious, chickenpox in children is usually a mild disease with few complications and a low fever. Occasionally, if the rash is severe, the fever may be higher. Chickenpox is more serious in adults, who usually have a higher fever and general malaise. It can cause damage to the eyes and, in males, the testes. An adult with chickenpox also requires a longer period of recuperation than does a child. The most common complaint about chickenpox from both children and adults is the itching caused by the lesions. Though scarring from chickenpox is rare, it is important not to scratch the lesions, as scratching may cause scarring.
Treatment
Because chickenpox is usually a mild disease, no drug treatment is prescribed. Pain relief, in the form of acetaminophen (i.e., Tylenol) is recommended rather than salicylate, or aspirin. Salicylate may cause Reye’s syndrome, a very serious neurological condition that is especially associated with aspirin intake and chickenpox; in fact, 20-30% of the total cases of Reye’s syndrome occur in children with chickenpox. It is therefore important to control pain in children with chickenpox (or any other respiratory illness) with acetaminophen, not aspirin. Adults should also take acetaminophen if they have chickenpox.
The itching of the lesions can sometimes be controlled with calamine lotion or special preparations that are put into bath water. Antihistamines may also help relieve itching. The itching becomes less severe as the lesions heal; however, because children are more likely to scratch the lesions, the potential for scarring is greater in children than in adults.
Chickenpox, although not deadly for most people, can be quite serious in those who have weakened immune systems, and drug therapy is recommended for these cases. Antiviral drugs (such as acyclovir) have been shown to lessen the severity and duration of the disease, although some of the side effects, such as gastrointestinal upset, can be problematic.
Complications
If the lesions are severe and the person has scratched them, bacterial infection of the lesions can result. This complication is managed with antibiotic treatment. A more serious complication is pneumonia. Pneumonia is rare in otherwise healthy children and is more often seen in older patients or in children who already have a serious disease, such as cancer. Pneumonia is also treated with antibiotics. Another complication of chickenpox is shingles. Shingles are painful outbreaks of skin lesions that occur some years after a bout with chickenpox. Shingles are caused by VZV left behind in the body, which then becomes reactivated. Shingles causes skin lesions and burning pain along the region served by a specific nerve. It is not clear why VZV is reactivated in some people and not in others, but many people with compromised immune systems can develop severe, even life-threatening cases of shingles.
Pregnant women are more susceptible to chickenpox, which also poses a threat to both prenatal and newborn children. If a woman contracts chickenpox in the first trimester (first three months) of pregnancy, the fetus may be at increased risk for birth defects such as scarring and eye damage. A newborn may contract chickenpox in the uterus if the mother has chickenpox five days before birth. Newborns can also contract chickenpox if the mother has the disease up to two days after birth. Chickenpox can be a deadly disease for newborns—the fatality rate from chickenpox in newborns up to five days old is about 30%. For this reason, women contemplating pregnancy may opt to
KEY TERMS
Immunocompromised— A condition in which the immune system is weakened, as during chemotherapy for cancer or infection with AIDS.
Reye’s syndrome— A neurological condition that usually occurs in children; associated with a respiratory illness and aspirin intake.
be vaccinated with the new VZV vaccine prior to conception if they have never had the disease. If this has not been done and a pregnant woman contracts chick-enpox, an injection of varicella-zoster immunoglobulin can lessen the chance of complications to the fet us.
Chickenpox and environmental factors
Researchers have long noted the seasonality of chickenpox. According to their research, chickenpox cases occur at their lowest rate during September. Numbers of cases increase throughout the autumn, peak in March and April, and then fall sharply once summer begins. This cycle corresponds to the typical school year in the United States. When children go back to school in the fall, they begin to spread the disease; when summer comes and school ends, cases of chick-enpox diminish. A typical “mini-epidemic” within a school occurs when one child contracts chickenpox. This child rapidly infects other susceptible children. Soon, all the children who had not had chickenpox contract the disease within two or three cycles of transmission. It is not uncommon for high numbers of children to be infected during one “mini-epidemic.”
Immunity and vaccination
Contrary to popular belief, it is possible to get chickenpox a second time. If a person had a mild case during childhood, his or her immunity to the virus may be weaker than that of someone who had a severe childhood case. In order to prevent chickenpox, especially in already-ill children and immunocompromised patients, the VZV vaccine, consisting of live, attenuated (modified) VZV is used. Immunization recommendations of the American Academy of Pediatrics state that children between 12 and 18 months of age who have not yet had chickenpox should receive the vaccine. Immunization can be accomplished with a single dose. Children up to the age of 13 who have had neither chickenpox nor the immunization should also receive a single dose of the vaccine. Children older than age 13 who have never had either chickenpox or the vaccine should be immunized with two separate doses, given about a month apart. The vaccine provokes strong immunity against the virus. Although some side effects have been noted, including a mild rash and the reactivation of shingles, the vaccine is considered safe and effective.
See also Childhood diseases.
Resources
PERIODICALS
Malhotra, R. “Nasolacrimal Duct Obstruction Following Chicken Pox.” Eye 16, no. 1 (2002): 88-89.
Ortolon, Ken. “Short On Shots.” Texas Medicine 98, no. 5 (2002): 30-33.
“Varicella Seroprevalence In A Random Sample Of The Turkish Population.” Vaccine 20, Issue: no. 10 (2002): 1425-1428.
OTHER
Centers for Disease Control and Prevention. “Varicella Disease (Chickenpox)” <http://www.cdc.gov/nip/diseases/varicella/>(accessed November 21, 2006).
MayoClinic.com “Chickenpox” <http://www.mayoclinic.com/health/chickenpox/DS00053>(accessed November 25, 2006).
Kathleen Scogna