Measles is a highly infectious skin disease caused by a virus (fam. Paramyxoviridae). It tends to occur as epidemics and remains a leading cause of death among young children. It is transmitted by nose and throat secretions. Unimmunized children under five years of age, and especially infants, are at highest risk for measles and its complications, including death. Infected infants may suffer from severe diarrhoea, possibly causing dehydration, inflammation of the middle ear and severe respiratory tract infections.