Semifield system and experimental huts bioassays for the evaluation of spatial (and topical) repellents for indoor and outdoor use

In this chapter, we describe considerations for the design of experiments to measure the protective efficacy of bite prevention tools against mosquito vectors. The chapter focuses on the evaluation of spatial repellents (specifically volatile pyrethroids) and topical repellents under semifield conditions including a description of the semifield system and experimental huts used to simulate outdoor and indoor use settings, respectively. We also explain the preparation needed for conducting an experiment in these bioassays to maximise data reproducibility as well as the limitations of the experimental systems. Bite prevention technologies are ultimately designed to prevent the transmission of pathogens by inhibiting bites and in some cases killing the vector. We explain the primary outcomes used to measure the efficacy of bite prevention tools, analysis, and data interpretation. We also describe the relationship between data collected in the semifield and the field setting. The chapter ends with a brief description of how these endpoints can be used in mathematical modeling to simulate the expected public health outcome when bite prevention tools are implemented alone or in combination with other vector control tools for the prevention of vector-borne disease.