Rapid epidemiological mapping of onchocerciasis in areas of Uganda where Simulium neavei SL is the vector

Abstract

Objective: To test whether Rapid Epidemiological Mapping of Onchocerciasis (REMO) was suitable for mapping of onchocerciasis in foci where S.neavei sl is the primary vector.
Design: Topographical maps of scale 1:250,000 were used in demarcating regions into ecotopographic divisions and zones in order to identify potential onchocerciasis endemic areas.
Setting: The study was conducted in Kabarole and Nebbi districts. High-risk communities were selected 30 km from each other, and closest to rivers where vector breeding appeared likely. Secondary and additional communities were selected 10 km and 20 km away from high-risk communities, respectively.
Subjects or participants: Communities were mobilied for nodule palpation. A sample of thirty males aged at least 20 years, from each community that had lived in the area for at least ten years, were randomly selected and examined.
Interventions: Individuals positive for at least one nodule were expressed in terms of Nodule Prevalence Rates (NPR) which were used to map the distribution of onchocerciasii.
Main outcome measures: Coefficient of variation (CV) of Nodule Prevalence Rates between high risk secondary communities.
Results: In Kabarole district, the results indicated a low coefficient of variation (CV) of 75 in NPR between high risk and secondary communities while in Nebbi district, higher CV of 187.4 was attained. The less varied NPR implies that communities in Kabarole were almost equally exposed to onchocerciasis while highly varied situation in Nebbi indicated decreasing NPR with increasing distance from high-risk communities.
Conclusion: REMO is applicable in areas where S.neavei sl k the primary vector, for identification and mapping communities requiring mass treatment with ivermectin.