Evaluation of Known Visual and Chemical Cues for Surveillance of the Dengue and Chikungunya Vector, Aedes Aegypti, in Busia and Kilifi Counties, Kenya.

Abstract

Dengue and chikungunya are arboviral diseases transmitted by Aedes aegypti. Currently there is an upsurge of these infections worldwide, Kenya included. Due to lack of effective human cure, vector surveillance is critical for control and prevention of these diseases. The purpose of this study was to improve sensitivity of existing surveillance tool using potentially identified light cues ultraviolet light and incandescent light as well as odor cues hexanoinc acid and linalool oxide in two study sites previously found to harbor Aedes aegypti the vector, in Busia and Kilifi counties. The identified cues were blended in biogent sentinel site trap (BGS-1) and effect tested following Latin square design. Trap catches for every treatment were entered in excel and performance in terms of counts compared in R using generalized linear model (GLM) relative to controls at 95% confidence level of significance. Generally, there were more Ae. Aegypti trapped in Kilifi than Busia. The results obtained show that BG traps baited with UV or incandescent light comparably increased catches of Ae. aegypti 40-57% in Kilifi and 24% in Busia although not significantly from the control BG trap. The findings of this study confirm the visual attractive effect of BG trap alone to Ae. aegypti with differential but marginal effect of UV or incandescent light on trap catches. On the other hand, results on odor cues showed decreased catches of Ae. aegypti among the blends constituted. In fact, the blends of the two odorants decreased captures about 2-4 fold when compared the individual compounds (LO or HA) to caches indicating that combining plant- and human-derived odors may elicit a masking effect in trapping this vector. Thus, the usefulness of combining plant and animal odorants in Ae. aegypti trapping needs further investigation. The results underscore the importance of detailed knowledge of interactive effect of combining plant and animal odorants for proper lure formulation and development.