The development and evaluation of portable experimental huts for global malaria vector control decision-making - PROJECT SUMMARY Pyrethroid (PY) insecticides were the dominant chemical class used on insecticide-treated nets (ITNs), with an estimated 2.13 billion PY ITNs delivered in sub-Saharan Africa between 2004-2022. While the global malaria mortality rate halved between 2000 and 2015, progress has stalled and even started to reverse, coinciding with growing PY resistance. In recent years, ITNs containing the synergist piperonyl butoxide (PBO) and the pyrrole chlorfenapyr (CFP) have proven to be superior to PY ITNs in locations with high intensity PY resistance. With greater ITN choice, National Malaria Control/Elimination Programs (NMC/EPs) face critical vector control decisions which are complicated by the increased cost of new ITNs, regional variation in transmission intensity, mosquito species and highly dynamic insecticide resistance mechanisms. In response to the threat of PY resistance most countries in sub-Saharan Africa have pragmatically adopted a regional geographic mosaic of PY, PY-PBO and PY-CFP ITNs. Decision making is often based on insecticide susceptibility and ITN cone bioassay data, but the latter do not capture the efficacy of current, non-neurotoxic insecticides. The gold standard entomological method to assess ITN performance is experimental hut trials, but there are expansive geographical gaps with no existing infrastructure. Construction of new experimental hut sites is prohibitively expensive (estimated $150-300k per hut site) and inflexible due to their fixed location. In this study we will validate a novel portable experimental hut tent (PEHT) as a low-cost system for global vector control evaluation. PEHT design is based on World Health Organization (WHO) west African experimental hut dimensions, using seven feet high cabin style tents and 3D printer technology to prepare reproducible mosquito entry points. Specific Aim 1 is to optimize the PEHT design using existing mosquito spheres for release-recapture experiments; followed by validation alongside conventional concrete huts in an established field station in Tamale, Ghana. Comparability in trends will be assessed for all primary (mosquito mortality) and secondary (blood-feeding inhibition, deterrence and induced exophily) endpoints, to ensure that the PEHT can reliably capture all entomological measures necessary to predict the epidemiological benefit of the ITN under evaluation. Specific Aim 2 is to utilize PEHTs to determine the performance of PY, PY-PBO and PY-CFP nets, including aged community nets sampled from high malaria burden communities and tested against local, wild PY resistant mosquitoes in rural south-west Ghana. This will be followed by input of primary and secondary PEHT data into the Imperial College London MINT online model to support Ghana’s NMEP vector control decision making. PEHTs will have global utility for evaluation of ITNs to support regional, data driven vector control decision making. This innovative system would be particularly useful in areas of Nigeria and DR Congo, two countries with the greatest number of malaria cases and virtually no experimental hut infrastructure.
