Chicken pox or varicella is the most common disease of childhood that causes a rash. It is caused by the varicella-zoster virus (VZV), a herpes virus, and it is a disease seen worldwide. Because of the classic and unique appearance of the chicken pox rash, it has been known since antiquity. In the United States, approximately ninety percent of chicken pox cases occur in children from ages one to fourteen years. By the late teens, about ninety-five percent of individuals show evidence by the presence of antibodies that they have had the chicken pox.
For many years, chicken pox was felt to be a harmless disease of childhood. In fact, there are about 6,500 to 9,000 hospitalizations annually in the United States due to the illness, and about one hundred to two hundred deaths each year from complications due to chicken pox. While the complications and death rate for healthy children are minimal, the illness can be much more severe in adolescents and adults. After the chicken pox illness is over, the VZV establishes permanent latency in the dorsal root ganglia of the spinal cord. It is possible for the virus to reactivate at a later time and cause shingles, a painful skin disorder.
Who is likely to develop chicken pox?
All adolescents are susceptible to chicken pox unless they have already had the illness or have received the vaccination against the disease. The usual source of infectious material is the sores seen in patients with chicken pox. These sources are teeming with VZV. Most patients are contagious for one to two days prior to the onset of the chicken pox rash and for about five days after the rash begins. When the skin sores are crusted, it is much less likely that the patient can transmit the illness.
In households where one family member has chicken pox, the likelihood that other susceptible members will acquire the disease is very high. Teens who are immunocompromised due to other illnesses may have a more severe case of chicken pox, and those individuals who are on chronic aspirin therapy could develop Reye’s syndrome as a complication. Teens with chronic skin problems such as eczema are more prone to infection of the chicken pox sores.
What are the symptoms of chicken pox?
After a susceptible adolescent is exposed to an individual who is contagious with chicken pox, there is an incubation period of ten to twenty-one days prior to the onset of symptoms. Although symptoms may vary, one to two days prior to the onset of the chicken pox rash, an adolescent may experience malaise, fever, headache and loss of appetite. The chicken pox rash usually appears first on the scalp, face, chest or back. Typically 250 to 500 lesions occur over a five-day period that are initially very itchy and red. The lesions evolve from fluid filled vesicles that become cloudy, then finally crust and dry out. Most patients feel the sickest around day four of the rash when fever, itchiness and other discomfort peaks. The sores may also appear on mucous membranes including the eye, throat, vagina and anus. Around seven days after the onset of the chicken pox rash, most sores are dried and crusted, and the adolescent may return to his or her usual activities.
The complications of chicken pox infection include bacterial infections of the skin. Scratching of the itchy chicken pox sores can introduce bacteria into the lesions and cause a bacterial infection. These infections are typically due to Streptococcus or Staphylococcus bacteria. The infection can range in severity from mild to life threatening. Other complications include inflammation of the brain (encephalitis), difficulty with walking, pneumonia and seizures. Although pneumonia due to chicken pox is rare in adolescents, it is more common in high-risk individuals and can lead to death.
Bacterial infection of the sores may lead to scarring. It is not uncommon to have a lighter skin color around the area of the sores for about a year after the infection is over.
How is chicken pox evaluated?
Most clinicians who care for adolescents will recognize chicken pox based on the classic appearance and timing of the rash. No blood tests or other laboratory work are generally necessary to confirm the diagnosis.
How is chicken pox treated?
All adolescents with chicken pox should be kept home until the sores are dried and crusted. To relieve the itchiness of the rash, physicians often recommend antihistamines such as diphenhydramine. Calamine lotion is used topically on the sores, and daily colloidal oatmeal baths can bring relief from the itch. Cool packs are also helpful. Tylenol may be used for fever or discomfort. DO NOT GIVE ASPIRIN TO ANY ADOLESCENT WITH CHICKEN POX!
Because adolescents are at higher risk for moderate or severe chicken pox, many physicians recommend the use of oral acyclovir, an anti-viral medication. If given early enough in the illness, acyclovir has been shown to decrease the number and duration of chicken pox skin lesions. If the adolescent is pregnant, then her physician should be contacted as soon as possible.
Antibiotics may be used for secondarily infected chicken pox sores. If an adolescent becomes dehydrated during the chicken pox illness, then intravenous fluids and hospitalization may be required. Hospitalization may also be necessary for pneumonia due to chicken pox.
How is chicken pox prevented?
It is difficult to prevent transmission of chicken pox since the infection is contagious to others one to two days prior the appearance of the rash. However, chicken pox is preventable by routine administration of the live virus varicella vaccine.
The varicella vaccine was licensed for general use in 1995, and it is recommended for use in healthy individuals age one year and older. See this website from the Centers for Disease Control for further information: http://www.cdc.gov/nip/vaccine/varicella/default.htm
For children under age thirteen years, one dose of the vaccine is recommended. More than ninety-five percent of healthy children between age one year and twelve years develop an immune response to the vaccine. For children age thirteen years and older, two doses of the vaccine, at least four weeks apart is recommended. The vaccine is eighty-five percent to ninety percent effective in preventing chicken pox in children during outbreaks. It is said to be one hundred percent effective in preventing moderate or severe chicken pox. The vaccine produces protection against chicken pox for at least eleven years; studies in Japan indicate protection for twenty years.
Many states require children to receive the varicella vaccine prior to entrance into day care or kindergarten. Some states require it also for promotion into middle school, and some colleges require the vaccine or history of chicken pox illness prior to matriculation as a freshman.
All adolescents should be immune to chicken pox prior to arrival at college. Not only is the illness more severe in older adolescents, but also there are significant public health issues for colleges when there is an outbreak of chicken pox. Due to the necessity to isolate each individual with chicken pox, college students may miss a significant amount of class work due to the illness. If a rising college freshman is not immune to chicken pox by the summer prior to college, then he or she should discuss immunization with their physician.
Related topics:
Encephalitis, immunizations, Reye’s syndrome, seizures, skin disorders
