DefinitionChickenpox is one of the classic childhood diseases. A child or adult with chickenpox may develop hundreds of itchy, fluid-filled blisters that burst and form crusts. Chickenpox is caused by a virus.The virus that causes chickenpox is varicella-zoster, a member of the herpesvirus family. The same virus also causes herpes zoster (shingles) in adults.Alternative NamesVaricella; Chicken poxCauses, incidence, and risk factorsIn a typical scenario, a young child is covered in pox and out of school for a week. The first half of the week the child feels miserable from intense itching; the second half from boredom. Since the introduction of the chickenpox vaccine, classic chickenpox is much less common.Chickenpox can be spread very easily to others. You may get chickenpox from touching t