Abstract
BackgroundThe global strategy for elimination of lymphatic filariasis is by annual mass drug administration (MDA). Effective implementation of this strategy in endemic areas reduces Wuchereria bancrofti in the blood of infected individuals to very low levels. This minimises the rate at which vectors successfully pick microfilariae from infected blood, hence requiring large mosquito numbers to detect infections. The aim of this study was to assess the feasibility of using trained community vector collectors (CVCs) to sample large mosquito numbers with minimal supervision at low cost for potential scale-up of this strategy.MethodsCVCs and supervisors were trained in mosquito sampling methods, i.e. human landing collections, pyrethrum spray collections and window exit traps. Mosquito sampling was done over a 13-month period. Validation was conducted by a research team as quality control for mosquitoes sampled by CVCs. Data were analyzed for number of mosquitoes collected and cost incurred by the research team and CVCs during the validation phase of the study.ResultsA total of 31,064 and 8720 mosquitoes were sampled by CVCs and the research team, respectively. We found a significant difference (F(1,13) = 27.1606, P = 0.0001) in the total number of mosquitoes collected from southern and northern communities. Validation revealed similar numbers of mosquitoes sampled by CVCs and the research team, both in the wet (F(1,4) = 1.875, P = 0.309) and dry (F(1,4) = 2.276, P = 0.258) seasons in the southern communities, but was significantly different for both wet (F(1,4) = 0.022, P = 0.005) and dry (F(1,4 ) = 0.079, P = 0.033) seasons in the north. The cost of sampling mosquitoes per season was considerably lower by CVCs compared to the research team (15.170 vs 53.739 USD).ConclusionsThis study revealed the feasibility of using CVCs to sample large numbers of mosquitoes with minimal supervision from a research team at considerably lower cost than a research team for lymphatic filariasis xenomonitoring. However, evaluation of the selection and motivation of CVCs, acceptability of CVCs strategy and its epidemiological relevance for lymphatic filariasis xenomonitoring programmes need to be assessed in greater detail.
Highlights
The global strategy for elimination of lymphatic filariasis is by annual mass drug administration (MDA)
Mosquito collection Over the 13-month study period, a total of 31,064 and 8720 mosquitoes were sampled by Community vector collectors (CVC) and the Noguchi Memorial Institute for Medical Research team, respectively
Higher numbers of mosquitoes were collected by the research team compared to CVCs in the months when both constituencies collected mosquitoes (Fig. 2a, b)
Summary
The global strategy for elimination of lymphatic filariasis is by annual mass drug administration (MDA). Effective implementation of this strategy in endemic areas reduces Wuchereria bancrofti in the blood of infected individuals to very low levels. This minimises the rate at which vectors successfully pick microfilariae from infected blood, requiring large mosquito numbers to detect infections. There are various species of mosquitoes implicated in the life-cycle of the parasites, mainly of the genera Aedes, Anopheles, Coquillettidia, Culex and Mansonia [2] These species differ in their biology, distribution, ecology and transmission potential. It will be difficult for most of endemic countries to become verified as free of transmission or having entered the post-intervention surveillance phase by 2020 [1], as recognised recently at the Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN) in Kigali
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