Poliomyelitis: 20 years--the Pondicherry experience.

During a 20-year period, 12,830 cases of acute poliomyelitis in children (aged 1 month-12 years) were seen in a South Indian teaching hospital (Pondicherry). Almost three-quarters (72.4%) of children were below the age of 2 years. The median age at onset of poliomyelitis shifted from 19.5 months (in the period 1968-1977) to 11 months (in the years 1978-1987). After 1981, epidemic peaks were noted every third year. 66.3% of cases had not received even a single dose of oral polio vaccine and 14.7% cases were vaccine failures (in the years 1983-1987). Provocation of poliomyelitis occurred in 66% of children and usually followed intragluteal injections associated with treatment of non-specific fevers. The overall mortality was 2.13%, the major cause of death being respiratory failure (60%). Polio virus type 1 was the major isolate among selected cases studied during 1983-1987. The risk factors identified in our study are lack of immunization and administration of intramuscular injections during the pre-paralytic phase. Ensuring early administration of multiple doses of oral polio vaccine to infants and avoiding intramuscular injections in young febrile children are important measures for the control of poliomyelitis--a continuing problem in Southern India.