Abstract
BackgroundOnchocerciasis is a priority neglected tropical disease targeted for elimination by 2025. The standard strategy to combat onchocerciasis is annual Community-Directed Treatment with ivermectin (CDTi). Yet, high prevalence rates and transmission persist following > 12 rounds in South-West Cameroon. Challenges include programme coverage, adherence to, and acceptability of ivermectin in an area of Loa loa co-endemicity. Loiasis patients harbouring heavy infections are at risk of potentially fatal serious adverse events following CDTi. Alternative strategies are therefore needed to achieve onchocerciasis elimination where CDTi effectiveness is suboptimal.Methods/designWe designed an implementation study to evaluate integrating World Health Organisation-endorsed alternative strategies for the elimination of onchocerciasis, namely test-and-treat with the macrofilaricide, doxycycline (TTd), and ground larviciding for suppression of blackfly vectors with the organophosphate temephos. A community-based controlled before-after intervention study will be conducted among > 2000 participants in 20 intervention (Meme River Basin) and 10 control (Indian River Basin) communities. The primary outcome measure is O. volvulus prevalence at follow-up 18-months post-treatment. The study involves four inter-disciplinary components: parasitology, entomology, applied social sciences and health economics. Onchocerciasis skin infection will be diagnosed by skin biopsy and Loa loa infection will be diagnosed by parasitological examination of finger-prick blood samples. A simultaneous clinical skin disease assessment will be made. Eligible skin-snip-positive individuals will be offered directly-observed treatment for 5 weeks with 100 mg/day doxycycline. Transmission assessments of onchocerciasis in the communities will be collected post-human landing catch of the local biting blackfly vector prior to ground larviciding with temephos every week (0.3 l/m3) until biting rate falls below 5/person/day. Qualitative research, including in-depth interviews and focus-group discussions will be used to assess acceptability and feasibility of the implemented alternative strategies among intervention recipients and providers. Health economics will assess the cost-effectiveness of the implemented interventions.ConclusionsUsing a multidisciplinary approach, we aim to assess the effectiveness of TTd, alone or in combination with ground larviciding, following a single intervention round and scrutinise the acceptability and feasibility of implementing at scale in similar hotspots of onchocerciasis infection, to accelerate onchocerciasis elimination.
Highlights
Onchocerciasis is a priority neglected tropical disease targeted for elimination by 2025
Using a multidisciplinary approach, we aim to assess the effectiveness of TTd, alone or in combination with ground larviciding, following a single intervention round and scrutinise the acceptability and feasibility of imple‐ menting at scale in similar hotspots of onchocerciasis infection, to accelerate onchocerciasis elimination
Based on predictive model simulations, the World Health Organization (WHO) recommends that annual mass drug administration (MDA) for at least 15–17 years with high population coverage (80%) may impact on transmission and abate incidence of skin infection in younger individuals [1, 6]
Summary
Onchocerciasis is a priority neglected tropical disease targeted for elimination by 2025. The standard strategy to combat onchocerciasis is annual Community-Directed Treatment with ivermectin (CDTi). Onchocerciasis (river blindness) is a vector-borne, neglected tropical disease (NTD), caused by the filarial parasite Onchocerca volvulus. Based on predictive model simulations, the WHO recommends that annual MDA for at least 15–17 years with high population coverage (80%) may impact on transmission and abate incidence of skin infection in younger individuals [1, 6]. MDA has been conducted in the South-West region of Cameroon for more than 12 years in a strategy known as Community-Directed Treatment with IVM (CDTi), yet higher than expected prevalence and intensity of onchocerciasis persists including in children born in the CDTi period [7,8,9]
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