Measles Outbreak in a Suburb of Tokyo, Japan, in 1998-1999

A 1998-1999 outbreak of measles in Kawasaki City was studied to provide an up-to-date epidemiological understanding of the disease in Japan. 21 of the 69 total patients (30.4%) seen at the hospital were under 1 y of age. None of the 69 patients had received measles vaccine. 43 out of 50 nasopharyngeal swabs subjected to polymerase chain reaction assay (86%) were positive for the hemagglutinin (H) gene. The measles strain isolated from patients was classified as a D3 genotype. Such outbreaks are important epidemiologically, and these findings shed light on vaccination and immunity patterns in this urban population.