Dinâmica de ocorrência de Aedes aegypti e Aedes albopictus em residências urbanas de Manaus, Brasil

Abstract

Aedes aegypti and Ae. albopictus are the vectors of dengue, the most important arboviral disease of humans. Dengue prevention heavily relies upon vector control, and this requires detailed knowledge of the population ecology of these species. Yet, all reports on Aedes ecology published to date assume that the vectors are truly absent from sites where they are not detected; since no perfect detection method exists, this assumption is questionable. Imperfect detection may bias estimates of key vector surveillance/control parameters, including site-occupancy (infestation) rates and control intervention effects. Here, we used a modeling approach that explicitly accounts for imperfect detection to model the effects of regular (municipal) Aedes control interventions on site-occupancy dynamics. The data, collected in partnership with the Leônidas and Marie Deane Institute, encompass 38 months of vector monitoring at 55 sites in the Tancredo Neves neighborhood, Manaus. Meteorological and dwelling-level covariates were also considered. Ae. aegypti siteoccupancy was estimated as ~0.9, one order of magnitude higher than the house infestation index reported by routine surveillance (based on rapid larval surveys ) and moderately higher than ascertained with simple oviposition traps (~0.7). Regular vector control interventions, based on breeding-site destruction, had small negative effects, indistinguishable from zero, on the probabilities of dwelling infestation by dengue vectors. Site-occupancy fluctuated seasonally, mainly due to the negative effects of high temperatures in June-September. Rainfall and dwelling-level covariates were poor predictors of infestation. Our results show that regular dengue vector surveillance/control municipal systems perform surprisingly poorly. Both the results of rapid larval surveys and the ineffectiveness of control campaigns suggest that Aedes breeding sites are often overlooked by vector control agents. Better alternatives are urgently needed, particularly for the reliable assessment of infestation rates in the context of control program management. The approach we present here, combining oviposition traps and site-occupancy models, could greatly contribute to the development and testing of such alternatives.