The outbreak of mumps in a small island in Japan

A major mumps outbreak occurred on a small island, Ikeshima. in Nagasaki Prefecture from August 1994 to February 1995. There were 236 patients with the mumps at Ikeshima Miners' Hospital during that period. The Measles-Mumps-Rubella (MMR, Toitsukabu) vaccination coverage in the 43 children at the nursery school was 65.1% and it was 61.9% in the 21 children aged 4-5 years not attending the nursery school. Coverage was 66.6% in the 63 kindergarten students and 53.7% in 56 first-graders. The overall MMR vaccination coverage among these children was 61.7% (113/183) from 1989 to 1992. Children from the second grade to junior high school received monovalent mumps vaccine, Torii strain. None received Zishakabu MMR. The age of the patients ranged from 1 to 43 years, with a mean of 9.1 years. The majority (77.5%) were primary school children. The attack rates for vaccinated and unvaccinated children in grades one to six were: 6.7% (2/30) and 88.5% (23/26), 25% (3/12) and 44.1% (30/68), 11.1% (1/9) and 64.4% (29/45), 25% (2/8) and 60% (45/79), 22.2% (2/9) and 35.9% (28/78). 0% (0/5) and 24.7% (18/73), respectively. The overall frequency in the primary school was 41.4% (183/442 children). The frequency in the nursery school for children aged 4-5 years was 14.0% (6/43). It was 17.5% (11/63) in children aged 5-6 years in the kindergarten, 5.2% (11/213) in children not attending school with an age range of 1-5 years, and 4.2% (10/237) in junior high school students. Although the frequencies of MMR coverage for the nursery school children and kindergarteners were not high enough to eradicate mumps outbreaks, the MMR vaccination program was thought to have influenced the low frequency of mumps among the children. Close physical interactions among the first-graders would have contributed to their high frequency of mumps. Some patients presented with suspected mumps parotitis several times, but no such serological confirmation of reinfection was obtained.