A systematic review to understand the value of entomological endpoints for assessing the efficacy of vector control interventions

To guide implementation of vector control interventions in Europe, a stronger evidence base of their efficacy and effectiveness is needed. Currently, epidemiological endpoints are used to demonstrate the public health value of a vector control intervention. This systematic literature review aimed to help assess whether entomological endpoints (such as mosquito abundance, infection rates, inoculation rates, parity rate as proxy for longevity, or others) can be used on their own as evidence of efficacy of vector control interventions against vector-borne diseases. We searched electronic bibliographic databases (The Cochrane Library, CAB Abstracts, MEDLINE and Web of Science) for intervention trials where vector control interventions were evaluated and extracted epidemiological and entomological effect size estimates. The selection process resulted in 31 studies (extracted from 35 publications) for which both types of endpoints were available. The final database included studies on malaria (n=16), dengue (n=9), leishmaniasis (n=5) and tick-borne diseases (n=1). Epidemiological and entomological effect sizes often pointed in the same direction (i.e. both favouring intervention or favouring control). However, based on the statistical inference (whether the effect size estimate is significantly different from no-effect) of the results, we observed some disagreement between endpoints, though we rarely saw complete disagreement in effect estimates. This review illustrates the complex relation between entomological and epidemiological endpoints. Based on this review, it is concluded that evaluating interventions on entomological endpoints only is insufficient to understand their potential epidemiological impact. To better asses the value of entomological endpoints for the assessment of efficacy of vector control intervention, there is a need for studies to be powered for both epidemiological and entomological endpoints.