A childhood infection that causes a fever and widespread crops of blisters

  • Mainly affects unimmunized children between the ages of 2 and 10
  • Gender, genetics, and lifestyle are not significant factors

Chickenpox, sometimes called varicella, is a common viral infection that mostly affects young children. The infection, with its characteristic rash of blisters, is caused by the varicella zoster virus, which also causes herpes zoster. The virus is infectious and is easily transmitted in airborne droplets from the coughs and sneezes of infected people or by direct contact with the blisters. You can catch chickenpox from someone who has either chickenpox or herpes zoster (shingles) if you are not immune but you cannot catch shingles from a person who has chickenpox.

The illness is usually mild in children, but symptoms are more severe in young babies, older adolescents, and adults. Chickenpox can also be more serious in people with reduced immunity, such as those with AIDS (see HIV infection and AIDS).

What are the symptoms?

The symptoms of chickenpox appear 10–21 days after infection. In children, the illness often starts with a mild fever or headache; in adults, there may be more pronounced flu-like symptoms (see Influenza). As infection with the virus progresses, the following symptoms usually become apparent:

  • Rash in the form of crops of tiny, red spots that rapidly turn into itchy, fluid-filled blisters. Within 24 hours the blisters dry out, forming scabs. Successive crops occur for 1–6 days. The rash may be widespread or consist of only a few spots, and it can occur anywhere on the head or body.

  • Sometimes, discomfort during eating caused by spots in the mouth that have developed into ulcers.

A person with chickenpox is contagious from about 2 days before the rash first appears until up to 6 days after the rash has first appeared.

The most common complication of chickenpox is bacterial infection of the blisters due to scratching. Other complications include pneumonia, which is more common in adults, and, rarely, inflammation of the brain (see Viral encephalitis). Newborn babies and people with reduced immunity are at higher risk of complications. Rarely, if a woman develops chickenpox in early pregnancy, the infection may result in fetal abnormalities.

What might be done?

Chickenpox can usually be diagnosed from the appearance of the rash. Children with mild infections do not need to see a doctor; rest and simple measures to reduce fever (see Bringing down a fever) are all that are needed for a full recovery. Calamine lotion (see Antipruritic drugs) may help to relieve the itchiness of the rash. To prevent skin infections, especially in children, keep fingernails short and avoid scratching. People who are at risk of severe attacks, such as babies, older adolescents, adults, and people with reduced immunity, should be seen by their doctor immediately. An antiviral drug may be given to limit the effects of the infection, but it must be taken in the early stages of the illness in order to be effective.

Children who are otherwise healthy usually recover within 10–14 days from the onset of the rash, but they may be left with permanent scars where the blisters have been scratched and then developed a bacterial infection. Adolescents, adults, and people who have reduced immunity take longer to recover from chickenpox.

Can it be prevented?

One attack of chickenpox gives lifelong immunity to the disease. However, the varicella zoster virus remains dormant within nerve cells and may reactivate years later, causing herpes zoster. Immunization against chickenpox is not recommended for healthy children or adults, except for health care workers who are not immune and people who are not immune and are living with somebody who has a weakened immune system.

Chickenpox rash

Itchy, fluid-filled blisters are usually widespread all over the head and body in chickenpox. The blisters, seen here on the abdomen, form scabs within 24 hours.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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