Semi-field studies and village-based trial to assess the impact of anopheline populations from zooprophylaxis aided ivermectin-based vector elimination (ZAIVE), in peridomestic cattle, Highlands of Vietnam

In line with regional goals in the Greater Mekong Subregion (GMS), Vietnam is committed to national malaria elimination by 2030. However, interventions targeting vulnerable populations in forested areas are lacking. Ivermectin, an endectocidal drug, has recently emerged as a potential new tool towards malaria elimination, as humans and animals retain blood concentrations that impact feeding anophelines (decreased fecundity, shortened lifespan, and lethality). Zooprophylaxis is a strategy that uses herd animals as bait to attract vectors; these alternative feedings provide passive protection to human populations. High cattle ownership in many rural communities suggests combining these strategies in an ‘attract-and-kill’ approach. This study utilizes semi-field testing and a community-scale randomized experimental design to assess if sufficient densities of ivermectin-treated cattle can drastically decrease vector populations and alter mosquito composition in village-based settings.

In Quy Nhon, Vietnam, colonies of Anopheles dirus ss and An. epiroticus will be allowed to feed on ivermectin-treated and control cattle in a semi-field study to ensure adequate drug dosing, and to quantify impacts of ivermectin in local vectors. Thereafter, six villages in Krong Pa district (Gia Lai) will be randomized as either control or intervention areas. In intervention villages, full herds of all consenting households will be treated with a standard veterinary dosing of 1% ivermectin by injection. At all village study sites (intervention and control), CDC light traps, cattle-baited trapping, and human-landing catches will be used to survey anopheline populations before and after the ivermectin dosing of cattle. The primary endpoint will be reduction in captures from cattle-baited traps; secondary endpoints will be changes in vector population composition. Data collection was initiated in April 2019 and will be completed end-2019. These results will quantify impacts of ivermectin-treated cattle on vector populations towards development of a novel strategy targeting residual malaria transmission in the GMS

II. Village-based trial

Drug-based Strategies
Vector Control

Dec 2017 — Dec 2019

$125,000

Vietnam

Ivermectin for malaria