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Pathology => Human Diseases => Chicken Pox
Chicken Pox
Chicken Pox, also called varicella, contagious viral disease that affects mainly children. According to the Centers for Disease Control and Prevention (CDC), more than 4 million people develop chicken pox each year, and more than 95 percent of Americans will have had chicken pox by the time they reach adulthood.
Typically, chicken pox begins with a low fever, headache, rash, and a general feeling of sickness, or malaise. The rash, which usually covers the face, scalp, and trunk of the body, starts as red bumps but quickly develops into small blisters. The rash and the blisters are extremely itchy. As the disease progresses, the blisters break open and form scabs, which fall off after about one to two weeks. The incubation period-the time between initial infection and the first appearance of symptoms-is approximately two weeks.
Chicken pox is caused by Varicella zoster, a type of herpes virus. The virus spreads through the air via infected droplets emitted from the nose or mouth while coughing or sneezing. Touching the fluid from a chicken pox blister can also spread the disease. Chicken pox is contagious for approximately seven days during a person's period of infection. Contagiousness begins about two days before symptoms appear and continues until all blisters have formed scabs. Doctors recommend keeping the infected person isolated from others during those seven days.
Chicken pox is usually much milder in children, for whom hospitalization is usually not required, than it is in adults. However, in children whose immune systems are weakened from such diseases as cancer or acquired immune deficiency syndrome (AIDS), the disease can be severe.
Contracting chicken pox provides immunity, or lifelong resistance, against the disease. However, after the symptoms disappear, the virus remains in the body's nerve cells and occasionally reactivates later in life, causing a disease known as shingles, an infection of the nerve fibers. Shingles usually occurs in people over 50, due to an age-related weakening of the immune system, and causes pain, burning, itching, inflammation, and blisters.
Treatment of chicken pox is usually limited to bed rest, acetaminophen for relief of fever and discomfort, and measures that soothe the itching, including lukewarm baths and application of topical medicines such as calamine lotion. Excessive scratching can cause infection of blisters, which can lead to scarring. Acyclovir, an antiviral drug, is used to treat severe cases of chicken pox, particularly in patients with a weakened immune system.
A child or adolescent with chicken pox should never be given aspirin or other salicylates because of the possible link to Reye's syndrome, a disease that develops only after a viral infection, characterized by high fever, vomiting, liver dysfunction, and swelling of the brain. Although Reye's syndrome is rare, it is life threatening.
In 1995 the United States Food and Drug Administration (FDA) approved the first vaccine for chicken pox for use in healthy children 12 months and older, as well as in adolescents and adults not yet exposed to the disease. The FDA has predicted that the vaccine will be 70 to 90 percent effective in preventing chicken pox, and that the people who still contract the disease will experience it in a milder form. Scientists are not yet certain whether the vaccine will protect a person for a lifetime, or whether a person's immunity will lessen over time. Diminished immunity may cause people who were vaccinated as children to contract the disease as adults. A study is now underway to determine the vaccine's long-term effectiveness and the possible need for booster shots.
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