POLIOMYELITIS OUTBREAK IN AN UNVACCINATED COMMUNITY IN THE NETHERLANDS, 1992-93

An outbreak of poliomyelitis occurred in the Netherlands between Septe mber, 1992, and February, 1993, after 14 years without endemic cases. The outbreak was due to pollovirus type 3 and involved 71 patients, of whom 2 died and 59 had paralysis. The patients were aged between 10 d ays and 61 years (median 18 years). None of the patients had been vacc inated, and all but 1 belonged to a socially and geographically cluste red group of people who refuse vaccination for religious reasons. Cont rol measures were taken within 5 days of notification of the first pat ient and included a wide offer of vaccination with the trivalent oral poliovirus vaccine to the population at risk. Sequence analysis of the viral genome showed closest similarity (96.7%) with a strain isolated in India in 1992, indicating that the virus probably originates from the Indian subcontinent. The difference, however, is still too large t o assume direct import. Extensive outbreak investigation at schools, i n the environment, at virus diagnostic laboratories, and in the genera l population showed no evidence of widespread circulation of the epide mic virus outside the groups at risk and area where these groups live. As in the previous outbreak in 1978, the general population, includin g the majority of unvaccinated people who live dispersed in the popula tion, seemed to be well-protected against poliomyelitis.