Varicella zoster virus (VZV) causes chicken-pox in children and both shingles (herpes zoster) and postherpetic neuralgia in adults but rarely in children. Most children get chickenpox before they are 10 years old.
The primary VZV infection results in chickenpox (varicella). The cases are usually mild, although rarely can have complications including encephalitis or pneumonia. Adults and older children usually get sicker than younger children. VZV remains dormant in the nervous system of the infected person, even after the symptoms of chickenpox have gone away. VZV reactivates later in adult life, in about 10-20% of cases, producing a disease known as shingles or herpes zoster. Serious complications of shingles include postherpetic neuralgia, zoster multiplex, myelitis, herpes ophthalmicus, or zoster sine herpete.
The illness was initially described in the ninth century by Rhazes, who noted that a "mild form of smallpox" did not protect against epidemic smallpox. The contagious nature of varicella skin lesions was first demonstrated by Steiner in 1875, but it was not until 1932 that Bruusgaard presented evidence that varicella could be transmitted by a patient with the rash of zoster.
As with other herpes viruses, VZV causes both an acute illness and a lifelong latent infection. The acute primary infection (varicella) commonly occurs during childhood. In a child with normal cellular immunity, primary VZV infection is relatively benign and self-limiting. In adults, however, primary infection can be more severe.
The pox, or fluid filled blisters, appear after an incubation period of 10 to 21 days. The infected person is contagious 1 to 2 days before breaking out with the pox and remains contagious while uncrusted blisters are present. The average child can develop 250 to 500 pox.
The chickenpox vaccine makes the illness very mild (less than 30 pox) and can even prevent the chickenpox disease completely.
Chickenpox is very contagious. You can get chickenpox from touching the fluids from a chickenpox blister, but you can also get it if someone with chickenpox coughs or sneezes near you. Humans are the only natural host for the Varicella zoster virus. Transmission occurs through direct contact with infectious lesions or mucous membrane contact with infected droplets. Infectivity usually begins 1 to 2 days before the onset of rash and persists until all vesicular lesions are dried and crusted. VZV lesions in HIV-infected patients, unlike those in the immunocompetent host, may heal slowly and can remain infectious for several weeks.
The key is to keep the child comfortable. Oatmeal baths can help. Topical lotions and oral antihistamines can help with the itching. Antiviral drugs can be prescribed.
Use Acetaminophen. DO NOT give Aspirin to children who may have chickenpox. Aspirin has been associated with a serious condition called Reyes Syndrome.
A VZV vaccine, Varivax, approved in 1995 by the U.S. Food and Drug Administration, is available in the United States. Since then, it has been added to the recommended vaccination schedules for children in Australia, the United States, and many other countries. Varicella vaccination has raised concerns in some that the immunity induced by the vaccine may not be lifelong, possibly leaving adults vulnerable to more severe disease as the immunity from their childhood immunization wanes. Vaccine coverage in the United States in the population recommended for vaccination is approaching 90%, with concurrent reductions in the incidence of chickenpox cases and hospitalizations and deaths due to VZV. Data has proved that the vaccine is effective in preventing varicella infection in healthy individuals and when breakthrough infections do occur, illness is typically mild. In 2007, the Advisory Committee on Immunization Practices (ACIP) recommended a second dose of the vaccine before school entry to ensure the immunity to varicella.