Persistence of onchocerciasis in Cameroon despite more than fifteen years of ivermectin treatment
(2018)
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- Authors
- Supervisors
- Robert, Annie
- Abstract
- Background: After more than 15 years of community-directed treatment with ivermectin (CDTI) in the Centre 1, Littoral 2 and West CDTI projects in Cameroon, the epidemiological evaluation conducted in 2011 revealed that onchocerciasis endemicity was still high in some communities. The conceptual framework for onchocerciasis elimination recommends in such case, to conduct additional phase 1A surveys at intervals of three to four years. Therefore, to assess the progress made towards the elimination of onchocerciasis in the three CDTI projects, we conducted in 2015 a cross-sectional survey in 23 unevaluated communities where the highest baseline endemicity levels were found. To investigate the potential reasons explaining this high endemicity, a cluster coverage survey was conducted during the same period in three health districts (HD), to assess the implementation of the CDTI, the 2014 therapeutic coverage and the five-year adherence to treatment. Results: In the Bafia HD (Centre 1), the microfilaridermia weighted prevalences varied from 24.4 to 57.0 % while in the Yabassi HD (Littoral 2), they varied from 12.3 to 59.3 %. In surveyed communities of the West Region, the microfilaridermia weighted prevalences varied from 0 to 41.6%. Except for Makouopsap which had 41.6%, all the 14 surveyed communities were below 15% with 11 (73.3%) communities having <5%. The community microfilarial load significantly dropped by 98–100% in all surveyed communities. The CDTI organization and the involvement of household’s heads were usually weak, with 84.0% (95% CI: 81.2-86.4) of them who didn’t participate in activities during the 2014 mass drug administration (MDA). The 2014 weighted therapeutic coverage was 64.1% (95% CI: 56.8-70.9), with no significant difference in the three HDs. The survey coverages were lower than the reported coverages with significant differences varying from 14.1 to 22.0%. Factors associated with the five-year adherence were a good organization and implication in CDTI activities and age (40+ years). Conclusion: After more than 15 years of CDTI, onchocerciasis was still mesoendemic in Bafia, Massangam and Yabassi HDs meanwhile there was an important progress towards the elimination in the other communities surveyed in the West Region. The implementation of the CDTI was not conducted as recommended, with a weak community participation or ownership and a low five-year adherence. The reported therapeutic coverages were higher than those observed in the framework of this study. The community ownership must be reinforced and innovative strategies like semi-annual ivermectin treatment plus a vector control strategy or the adjunction of a vector control strategy to the current annual treatment should be implemented. The National Onchocerciasis Control Program should modify its strategies for the CDTI implementation: there is a need to respect the different steps, to respect the roles and responsibilities of the actors, to timely procure ivermectin, to effectively supervise, and to conduct a data quality assessment. Implementing the Ugandan model (setting up a national elimination committee, refining elimination map, biannual ivermectin treatment, setting up a molecular laboratory, vector control) and considering the civil crisis in the two endemic regions of North West and South West can help the country in eliminating the disease. Implementation research should be conducted to improve the CDTI process and community ownership. Further anthropological and entomological studies could also provide better insights into our understanding of the persistence of the disease in these three CDTI projects.
- Affiliations
Citations
Kamga, G.-R. (2018). Persistence of onchocerciasis in Cameroon despite more than fifteen years of ivermectin treatment. https://hdl.handle.net/2078.5/123145