Chickenpox is a highly contagious viral infection in which a person develops extremely itchy blisters all over the body and it is common childhood disease caused by a virus in the herpes family of viruses called the varicella virus. The varicella virus can remain in the body for decades and become active again in adults, causing herpes zoster (shingles). Shingles involves the occurrence of painful skin sores along the distribution of nerves across the trunk or face.
Itchy blisters on a red base, progressing to scabs, appear along with newer blisters, mainly on the trunk, face, and scalp and last 5 to 10 days. Other symptoms include fever, headache, tiredness and loss of appetite.The chickenpox rash occurs about 10 to 21 days after coming into contact with someone who had the disease. The average child develops 250 to 500 small, itchy, fluid-filled blisters over red spots on the skin.
Chickenpox vaccine is very safe and effective at preventing the disease. Most people who get the vaccine will not get chickenpox. If a vaccinated person does get chickenpox, it is usually mild—with fewer blisters and mild or no fever. The chickenpox vaccine prevents almost all cases of severe disease.
3.7 million cases of varicella were estimated to occur in the US annually in the early 1990s. Data from 1992 showed that about 158,000 cases of chickenpox were reported and 100 deaths were reported. More than half of the deaths were in adults because chickenpox is more serious in adults than in children. Up to 20 percent of adults who get chickenpox can develop severe complications such as pneumonia. Other rare complications from chickenpox include serious bacterial infection of the lesions and brain inflammation, which is reported in less than one percent of children who get chickenpox. Most children and adults who develop severe complications from chickenpox disease have compromised immune systems or other health problems.