Discussion

Annual Community Directed Treatment with ivermectin (CDTi), the cornerstone of onchocerciasis control, has reached elimination targets in some areas but high infection levels persist despite long-term ivermectin distribution in other foci, including in South-West Cameroon. Challenges include program coverage, adherence to and acceptability of ivermectin in an area of Loa loa co-endemicity. Loaisis patients harbouring heavy infections are at risk of potentially fatal serious adverse events (SAEs) following CDTi. Alternative strategies are therefore needed to achieve onchocerciasis elimination where CDTi effectiveness is suboptimal.

The CouNTDown consortium has implemented two WHO-endorsed alternative strategies for the elimination of onchocerciasis in the Meme River basin, South-West Cameroon, where 15 rounds of CDTi MDA has not delivered expected impact on skin infection prevalence. Alternative strategies consist of testing and treating O. volvulus cases with doxycycline (DOX T&T), an anti-Wolbachia macrofilaricide, either alone or in combination with ground larviciding vector control (temephos).

A community-based before-after treatment cohort study is being conducted among the general population of the Meme River Basin, South-West Cameroon. Participants were diagnosed using skin snipping. O. volvulus patients enrolled in the DOX T&T study were treated daily with 100mg of Doxycycline for five weeks. Structured questionnaires were used to collect data on demographics, completion of treatment and onchocerciasis-related clinical signs. Focus-group discussions and in-depth interviews were used to investigate the acceptability of CDTi and DOX T&T strategy.

Logistic (prevalence) and negative binomial (infection intensity) mixed regression models will be used to assess the association between adherence to CDTi and infection levels, onchocercal skin disease or severe itching as well as the impact of DOX T&T on O. volvulus infection levels.

Here, we present the results of the baseline survey, including infection levels, prevalence of onchocercal skin disease and severe itching as well as their association with reported participation in CDTi, and the perceptions and attitudes towards CDTi.