Measles is a viral disease which spreads by droplet infection. One attack confers a high degree of immunity. Most people suffer from measles in childhood, and a mother who has had the disease confers passive immunity on her infant for the first six months of life. The infection is generalized, but the clinical evidence is mainly found in the respiratory tract, the skin, the mouth and the conjunctivae. Measles is prevalent during the first six months of the year with a peak incidence in March. The disease is notifiable in England but not in Scotland. The incubation period is about 10 days to the commencement of the catarrhal stage. A quarantine period is not necessary.