Related concepts:

varicella-zoster virus, chickenpox, shingles

Introduction to chickenpox:

Chickenpox is one of the classic childhood diseases. A young child covered in pox and out of school for a week is a typical scene. The first half of the week feels miserable from itching; the second half miserable from boredom. Since the introduction of the chickenpox vaccine, classic chickenpox is becoming less and less common.

What is chickenpox?

Chickenpox is caused by the varicella-zoster virus, a member of the herpesvirus family.

Chickenpox is one of the most contagious childhood illnesses. The disease is usually mild, although serious complications sometimes occur.

Some of the complications include impetigo (especially when the pox are scratched), hepatitis, pneumonia, encephalitis, meningitis, Reye syndrome, and severe invasive streptococcal infections.

Who gets chickenpox?

Before the vaccine, chickenpox was a standard feature of childhood. Still, most cases occur in children younger than ten. The illness is most common in the late winter and early spring.

Adults and older adolescents usually get sicker with chickenpox than younger children do. Years after having chickenpox, some adults and older adolescents may then get shingles, a painful second outbreak of a varicella-zoster virus rash.

Children under one year of age whose mothers have had chickenpox are not very likely to catch it. If they do, they often have mild cases because they retain partial immunity from their mothers' blood. Children under one year of age whose mothers have not had chickenpox, or whose inborn immunity has already waned, can get severe chickenpox.

Complications are more common in those who are immunocompromised either from an illness (e.g. AIDS) or from a type of medicine (e.g. chemotherapy). Some of the worst cases of chickenpox have been seen in children who have taken steroids during the incubation period, before they have any symptoms. These children are usually being treated for asthma.

What are the symptoms of chickenpox?

Most children with chickenpox act sick with vague symptoms, such as a fever, headache, tummy ache, or loss of appetite, for a day or two before (and 2-4 days after) breaking out in the classic pox rash.

The average child develops 250-500 small, fluid-filled blisters over red spots on the skin (“dew drops on a rose petal”). The blisters often appear first on the face, trunk, or scalp and spread from there. After a day or two, the blisters become cloudy and then scab. Meanwhile, new crops of blisters are springing up in groups.