What is chickenpox?
Chickenpox is an acute, highly infectious viral disease occurring primarily, but not exclusively, in children. Each year, between three and four million cases are reported in the United States, with the highest incidence occurring during the late winter and early spring. About ten to thirteen thousand of those affected became so ill that they require hospitalization; since the introduction of the varicella-zoster virus vaccine, the number of cases and the number of hospitalizations have dropped significantly.
The varicella-zoster virus (VZV) is responsible for chickenpox infection. Physical contact with an infected individual is not required, as the virus is transmitted from person to person via an airborne route.
Symptoms begin to appear about eleven to fifteen days after exposure. At first, they may resemble those of the common cold: sore throat, runny nose, malaise, and fever. Soon, red spots appear on the body, usually beginning on the trunk and scalp and spreading outward. Occasionally, the mucous membranes are affected as well, with spots appearing in the mouth and nasal passages. The spots develop into vesicles—raised bumps with clear, teardrop-shaped blisters that turn rapidly to crusty lesions within six to eight hours. The rash occurs in waves, with new spots developing as old ones heal and disappear. By the fifth or sixth day, no new lesions will develop, and the crusts will be gone in less than twenty days.
Chickenpox causes intense itchiness. The impulse to scratch can be overwhelming and can lead to one of the most common complications: bacterial skin infections. Scratching the lesions can also lead to ugly pox scarring. Other possible complications of chickenpox include viral pneumonia and viral encephalitis.
The diagnosis of chickenpox is almost always done on the basis of its symptoms, most notably its characteristic rash accompanied by fever. In the event that confirmation of the disease is necessary, the fluid in the lesions can be cultured, although by the time results are obtained (five to ten days), the disease is usually on its way to resolution.
In children, chickenpox, uncomfortable although it may be, is not considered a serious illness. The vast majority of cases are uncomplicated and resolve themselves within two to three weeks. Treatment is therefore primarily symptomatic, with an emphasis on controlling itching and reducing fever.
Oral antihistamines such as Benadryl (diphenhydramine) and Atarax (hydroxyzine) are effective in managing pruritus. Topical treatments, such as calamine lotion, and wet compresses may offer almost immediate relief. Fever is treated with acetaminophen. Aspirin is not an option because of its link to Reye’s syndrome, a potentially fatal condition characterized by vomiting, disorientation, and eventual coma. Ibuprofen should also be avoided, as it may be linked to secondary infections.
Some parents trim short the fingernails of infected children to keep them from scratching away the crusts of chickenpox lesions. This is one way of reducing the risk of secondary bacterial infections. Frequent bathing is also helpful in preventing this complication.
Although there is no cure for chickenpox, the oral antiviral drugs acyclovir, valacyclovir, and famciclovir have been shown to be effective in decreasing the intensity of itching, hastening the healing of skin lesions, and generally shortening the duration of the disease. To be effective, treatment must begin within twenty-four hours of the appearance of the rash.
The use of acyclovir is not recommended for most children because of the relatively benign nature of the disease in this age group. However, for some high-risk children, such as premature infants, therapy should be started within twenty-four hours of the onset of illness. In adolescents older than age thirteen, adults, and immunocompromised individuals, however, chickenpox may have severe complications, and this increased risk may be lessened with acyclovir therapy.
Affected newborns and immunocompromised persons may receive gammaglobulin intravenously or oral acyclovir immediately following exposure to the virus.
Chickenpox has been around for so long that there are conflicting accounts about how it got its name. One theory has it that when chickenpox was first described, it was noted that its lesions looked as if they were placed upon the skin rather than arising from the skin itself. They were compared to chickpeas—hence the name. Another idea is that the term “chickenpox” was intended to distinguish this weaker pox illness from the more life-threatening smallpox—the term “chicken” being used, as in “chickenhearted,” to mean weak or timid.
Chickenpox was not considered a distinct rash disease until 1553, when the Italian physician Filippo Ingrassia differentiated it from scarlet fever. In 1785, the English physician William Heberden gave the earliest clear description of varicella, having distinguished it from smallpox in 1768. In 1924, T. M. Rivers and W. S. Tillett reported the isolation of the chickenpox virus.
Throughout history, the treatment of chickenpox has been symptomatic. In the 1970s, however, a vaccine became available for persons in high-risk categories. In 1995, a vaccine called Varivax was approved by the US Federal Food and Drug Administration for use in children over the age of one; other brands of the vaccine are available in Canada, the United Kingdom, and Australia. Varivax is 70 to 90 percent effective in preventing chickenpox over the short term. Vaccinated individuals who still develop chickenpox get a milder form of the disease. Immunity from the vaccine may wane over time, so booster shots may be needed. The vaccine’s ability to provide long-term protection from chickenpox is still unknown.
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