An infectious disease that occurs in childhood. The cause is unknown, a virus being the most likely agent. It is a rare disease which normally occurs in closed communities. The incubation period is usually 5 to 6 days, sometimes longer. The most important symptoms are a skin rash with bright red, slightly raised spots. The rash begins on the face and spreads along the limbs and finally the trunk. The spots are then white in colour. New red spots also appear, so that the skin becomes highly mottled. There are no other symptoms of the disease, and there is no fever. The rash disappears after about a week. Complications do not arise, and no treatment is necessary.