The 1976-1977 rubella epidemic in Fukuoka city in southern Japan: epidemiology and incidences of complications among 80,000 persons who were school children at 28 primary schools and their family members.

From 1975 to 1977, a nationwide rubella epidemic occurred in Japan. This epidemic provided the last chance for the observation of natural rubella and its epidemiology without the influence of mass-vaccination for rubella and before changes in the epidemic pattern of rubella in the 1980's in Japan. Epidemiological and clinical data were obtained by questionnaires on school children in 28 selected primary schools and their family members (a total of 80,221 persons) in Fukuoka in southern Japan during the 1976-1977 rubella epidemic. At the end of 1975 the rubella epidemic was mainly in the western part of Fukuoka city and then it spread to the eastern part. After a break during the summer of 1976, the epidemic restarted in 1977 mainly in the eastern part with few cases in the western part. Rubella was identified clinically in 14,322 cases (18%) during the 1976 epidemic, the incidences in various age groups being as follows: children of below 6 years of age, 28%; primary school children, 37%; junior and senior high school students, 30%; adults of 18 to 30 years of age, 8%; adults of over 30 years of age, 1%. The incidence in primary school children in 1977 was 18%. Of the 14,322 cases of clinical rubella in 1976, 3 with encephalitis, 9 with purpura and 1,843 with joint complaints (pain and/or swelling of joints) were recorded. Rubella encephalitis was estimated to have occurred in 1 in 4,700 cases with clinical rubella, and purpura in 1 in 1,500 cases.(ABSTRACT TRUNCATED AT 250 WORDS)