Monitoring impact of oral poliovirus vaccine on poliomyelitis trends from physiotherapy records, Ilorin, Nigeria, 1981-1988.

During the eight years of a poliomyelitis control programme in Ilorin Local Government Area, Nigeria, 85% of children aged 12-23 months were estimated to have received three doses of trivalent oral polio vaccine. The estimated incidence of paralytic poliomyelitis decreased by 59%, indicating a low vaccine efficacy for the currently used TOPV. This has a serious implication for the World Health Organization's global poliomyelitis eradication strategy of immunizing at least 80% of children aged one year by the year 2000, that eradication may not be achieved by this strategy alone in tropical Africa. Supplementary strategies of mass OPV campaigns, combined IPV/OPV vaccine regimens, or the introduction of new generation of poliomyelitis vaccines may be needed. Similar low-cost efforts at documenting the impact of TOPV on the incidence of poliomyelitis using physiotherapy clinics as independent sentinels, are needed from other states of Nigeria. To increase the efficacy of the primary series of TOPV in Nigeria, the number of doses constituting the primary series should be increased to four (including one at birth). There is now reason to consider a properly timed combination of both IPV and OPV in Nigeria.