Poliomyelitis Outbreak in Israel in 1988: a Report with Two Commentaries

An outbreak of 15 cases of paralytic poliomyelitis caused by type 1 poliovirus between July and October, 1988, prompted mass vaccination of the whole Israeli population under the age of 40 years. The focus of the outbreak (12 cases) was the Hadera subdistrict, one of two subdistricts where enhanced inactivated poliovaccine (eIPV) had been the only poliovaccine used for infants since 1982. 9 of the 15 victims were 15 years or older, and 9 had previously been immunised with at least three doses of oral poliovaccine (OPV). The authors are divided in their interpretation of the findings. One group considered that the likely causative factors were the greater susceptibility of young adults previously vaccinated with OPV as well as transmission of wild poliovirus to susceptible people by children with low gut immunity against poliovirus after vaccination with eIPV; they concluded that a vaccination programme combining eIPV with OPV is the best option for Israel in future. The other group believed the causative factors were exposure to contaminated sewage or close social contact within the epidemic foci, the presence of an epidemic strain differing from the wild Mahoney and Sabin type 1 vaccine strains, and the lower seropositivity rates and geometric mean titres of neutralising antibodies to the epidemic than to vaccine strains; they believe that eIPV is the means to achieve effective control of poliomyelitis in Israel.