Control of a type 1 poliomyelitis epidemic in British Guiana, 1962-63, with trivalent oral poliovirus vaccine. 1. Epidemiological aspects.

An epidemic of poliomyelitis took place in British Guiana during the winter of 1962-63. A total of 485 paralytic cases occurred over a 10-week period, 90% in children under 5 years of age.The attack rate for the total population of more than half-a-million persons was 86.5 per 100 000. Type 1 poliovirus was isolated from stool specimens from 90% of the paralytic cases studied. Early in the epidemic, before virus was isolated, plans were developed for an extensive field study to characterize the epidemic and evaluate the effectiveness of trivalent vaccine as a practical control measure.Vaccine was administered to 85% of the children aged 5 or less over a 4-week period. A definite beneficial effect was noted; however, the epidemic might have been more impressively terminated had the programme been more rapidly administered. The importance of early recognition of an outbreak of poliomyelitis and of the rapid planning and execution of a vaccination programme is stressed.