House-to-house and school lameness surveys in Cameroon: a comparison of two methods for estimating the prevalence and annual incidence of paralytic poliomyelitis.

House-to-house and school lameness surveys were conducted in one urban and two rural regions of the United Republic of Cameroon. As in many other African nations, estimates of annual incidence by survey were significantly higher than those established by routine surveillance, and greater than 80% of all cases of paralysis were found to have occurred in children younger than 36 months of age. House-to-house surveys were more than six times more costly than school surveys and undoubtedly gave annual incidence rates closer to true rates. The value of the less costly school survey should not be overlooked, however, if base-line data are required at frequent intervals for use in the evaluation of control measures.