Still Mesoendemic Onchocerciasis in Two Cameroonian Community Directed Treatment with Ivermectin Projects Despite more than Fifteen Years of Mass Treatment

CaHReF 20116, Yaoundé Conges hall, 23 – 26 August 2016 , PL080

After more than a decade of community directed treatment with ivermectin (CDTI), onchocerciasis endemicity was still high in some communities according to the 2011 epidemiological evaluations. Some correctives measures were undertaken to improve the CDTI process and therefore reduce the burden of the disease. The objective of the present study was to assess the progress made towards the elimination of onchocerciasis in the Centre 1 and Littoral 2 CDTI-projects where the worst performances were found. A cross sectional survey was conducted in April 2015 in eight communities of two health districts (HD), Bafia in Centre 1 and Yabassi in Littoral 2, chosen because assessed at baseline and in 2011. All volunteers living for at least 5 years in the community, aged 5 years or more, underwent clinical and parasitological examinations. Individual compliance to ivermectin treatment was also assessed. Analyses of data were weighted proportionally to population size.
Results: In the Bafia and Yabassi HD, 514 and 242 individuals were examined with a mean age of 35.1 (standard deviation, sd: 20.7) and 44.6 (sd: 16.3) years, respectively. In the Bafia HD, the weighted prevalences varied from 24.4% to 57.0% for microfilaridermia and 3.6% to 37.4% for nodule carriage across the surveyed communities. The community microfilarial load (CMFL) in all the surveyed communities significantly dropped from 20.84-114.50 mf/ss in 1991 to 0.31-1.62 mf/ss in 2015. In the Yabassi HD, the weighted prevalences varied from 12.3% to 59.3% for microfilaridermia and from 1.5% to 3.7% for nodule carriage across the surveyed communities, while a significant drop was observed in CMFL, from 20.40-28.50 in 1999 to 0.48-1.74 mf/ss in 2015. The weighted therapeutic coverage of participants in 2014 varied from 65.8% (95% CI: 58.4-73.2) in Yabassi HD, to 68.0% (95% CI: 63.3-72.7) in Bafia HD, with important variations among communities.
Conclusions: After more than 15 years of CDTI, onchocerciasis is still mesoendemic in the surveyed communities. Further studies targeting therapeutic coverage, socio-anthropological CDTI implementation process and entomological studies would bring more insights to the persistence of the disease as observed in the present study.

onchocerciasis, ivermectin, persistence, elimination, Bafia, Yabassi, Cameroon