An acute, highly infectious viral disease with cough, fever, and maculopapular rash. It is of worldwide endemicity. The virus enters the body via the respiratory system, multiplies there, and circulates in the blood. Cough, sneezing, conjunctivitis, photophobia, and fever occur, with Koplik's spots (small red spots containing a bluish-white speck in the center) in the mouth. A rash appears after 14 days' incubation and persists 5–10 days. Serious complications may occur in 1 out of 15 persons; these are mostly respiratory (bronchitis, pneumonia), but neurological complications are also found. Encephalomyelitis occurs rarely. Permanent disabilities may ensue for a significant number of persons. Measles is one of the leading causes of death among children in the world, particularly in the developing countries. In unvaccinated populations, immunizing infections occur in early childhood during epidemics which recur after 2–3 years' accumulation of susceptible children. Transmission is by coughing or sneezing. Measles is infectious from the onset of symptoms until a few days after the rash has appeared. Second attacks of measles are very rare. Treatment is symptomatic. Killed virus vaccine should not be used, as certain vaccinees become sensitized and develop local reactions when revaccinated with live attenuated virus, or develop a severe illness upon contracting natural measles. Live attenuated virus vaccine effectively prevents measles; vaccine-induced antibodies persist for years. | 
