Onchocerca volvulus in the Damba District, Province of Uige, Northern Angola

The presence of foci of Onchocerca volvulus trasmission in Angola has been already documented by APOC (African Programme for Onchocerciasis control), but the definition of the endemicity level in the different regions has yet to be achieved. In six areas of the country only the CDTI (Community Directed Treatment with Ivermectin) project has been approved. In the Damba district, situated in the Northern Province of Uige, a collaboration between the Ministry of Health and the Italian NGO Medici con l'Africa - CUAMM has been underway for 4 years. The finding of a high prevalence of subcutaneous nodules, dermatologic and also ocular lesions prompted the medical team to perform a REMO (Rapid Epidemiological Mapping of Onchocerciasis, WHO/TDR) in collaboration with the Health Province of Uige and with the National WHO office. Objective: To map for the first time the prevalence of onchocerciasis in the Damba district, Province of Uige, Northern Angola. Briefly, based on favourable geo-climatic criteria for simulid habitat, 13 high-risk and 6 low-risk communities were selected. In each community, 50 adult males (age 20 to 60 years, resident in the area for at least 10 years) were randomly selected and clinically screened for nodules, skin lesions and blindness. Based on the prevalence of nodules, the communities were classified as hyper, meso and hypoendemic. Results: In 12 high-risk communities accepting to participate, 271/596 subjects overall (45.5%) had subcutaneous nodules: 8 communities were classified as hyperendemic (prevalence >40%). In 5 low-risk villages the prevalence of nodules was 43/252 subjects or 17%: 2 were mesoendemic (prevalence 20 to 40%) and 3 hypoendemic (<20%). Conclusion: We found a high prevalence of onchocerciasis in several communities, justifying to start a community control program (CDTI). Preliminary to this, a Rapid Assessment of Loa loa (RAPLOA) is necessary, according with the recommendations of the expert Committee on areas of co-endemicity (O. volvulus and L. loa infection), in order to avoid the risk of severe meningo encephalitis following ivermectin administration.