A single blister, typical during the early stages of the rash.
Chickenpox, also called varicella, is a viral disease due to Varicella zoster (a virus of the herpes group), affecting mainly children, usually in epidemics. It is contracted from other cases or from cases of shingles and is contagious, with an incubation period of 2 to 3 weeks. It causes malaise, fever, and characteristic vesicular rash – mainly on the trunk and face – which appears in crops. Infrequently hemorrhage or lung involvement occurs. It is rarely serious in the absence of underlying disease recovery is usual within a week. The possibility of contagion remains until the last scab has been shed. Chickenpox and shingles are caused by the same virus.