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.
Number of cases increases from winter to spring, and then gradually decreases towards the autumn. Estimatedly about 1,000,000 chickenpox patients, mostly infants, occur every year, though the overall incidence is decreasing (though slightly) in the recent three years . While 80% of the patients used to be under 4 years of age, since 2010 the percentage of this age group has been decreasing possibly owing to the increased vaccination coverage of this age group.