Cross-validation of the rapid epidemiological mapping of onchocerciasis endemicity in Anambra state, Nigeria.

In this evaluation study, the results of a previous, rapid, epidemiological mapping of onchocerciasis (REMO) from quota samples of six communities (two hyper-, two meso-, one hypo- and one non-endemic) in Anambra state, Nigeria, were cross-validated. The findings were based on observations on the prevalence of palpable onchocercal nodules and skin dipigmentation (leopard skin) in a sample of 50 adults resident in each community for at least 5 years. They indicate that the REMO results obtained earlier were reasonably valid. The influence of several factors (mobilization techniques, mobilization message, previous exposure of subjects to previous research studies and treatment intervention, community members' perception of susceptibility and their desire to benefit from treatment programmes) on the representativeness of cases and non-cases in the samples used for REMO is discussed.