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Implementation of test-and-treat with doxycycline and temephos ground larviciding as alternative strategies for accelerating onchocerciasis elimination in an area of loiasis co-endemicity: the COUNTDOWN consortium multi-disciplinary study protocol

  • Wanji, Samuel1, 2
  • Nji, Theobald Mue2, 1
  • Hamill, Louise3
  • Dean, Laura4
  • Ozano, Kim4
  • Njouendou, Abdel J.2, 1
  • Abong, Raphael A.1, 2
  • Obie, Elisabeth Dibando1, 2
  • Amuam, Andrew1, 2
  • Ekanya, Relindis1, 2
  • Ndongmo, Winston Patrick Chounna1, 2
  • Ndzeshang, Bertrand L.1, 2
  • Fung, Ebua Gallus2, 1
  • Nnamdi, Dum-Buo2, 1
  • Nkimbeng, Desmond Akumtoh1, 2
  • Teghen, Samuel1, 2
  • Kah, Emmanuel1, 2
  • Piotrowski, Helen4
  • Forrer, Armelle4
  • Khan, Jahangir A. M.4
  • And 10 more
  • 1 University of Buea, Buea, Cameroon , Buea (Cameroon)
  • 2 COUNTDOWN, Research Foundation for Tropical Diseases and Environment, Buea, Cameroon , Buea (Cameroon)
  • 3 Sightsavers, 35 Perrymount Road, Haywards Heath, UK , Haywards Heath (United Kingdom)
  • 4 Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK , Liverpool (United Kingdom)
  • 5 Monash University, Victoria, Australia , Victoria (Australia)
  • 6 Johns Hopkins School of Public Health, Baltimore, USA , Baltimore (United States)
  • 7 University of Yaounde I, Yaounde, Cameroon , Yaounde (Cameroon)
  • 8 West Herts Hospitals NHS Trust, Watford General Hospital, Vicarage Road, Watford, UK , Watford (United Kingdom)
Published Article
Parasites & Vectors
Springer (Biomed Central Ltd.)
Publication Date
Dec 04, 2019
DOI: 10.1186/s13071-019-3826-8
Springer Nature


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.

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