Chickenpox: or varicella is a common infection of children all seasons of the year caused by a virus which has been shown fairly conclusively to be related to that of herpes or shingles. Thus an adult with shingles can infect a child with chickenpox and vice versa. Chickenpox may also occur in infancy and in adults when its reaction is correspondingly severe. The incubation period is 10—15 days and the typical rash appears on the first day. This begins as tiny red spots in the area covered by the vest and spreads outwards to the limbs (unlike smallpox which starts on the limbs and moves inwards), the spots turn to blisters which finally become pustules and form scabs. Generally the rash is the first, and sometimes the only, symptom, but the child may be irritable, headachy, and have a slight temperature. No specific treatment exists (although if the child is irritable aspirin may be given and calamine lotion applied to the sores); there are no complications in the vast majority of cases. Quarantine period is three weeks from the beginning of the rash, but doctors are increasingly of the opinion that there is no reason why other members of the family should not be exposed to a harmless infection which confers immunity for life — other people’s children are, of course, another matter.