The Re-Invasion of Aedes aegypti in southern Arizona/northern Mexico

As the habitat and range of disease vectors continue to expand, an examination of dispersal in response to macro- and micro-level changes in human ecology is critical to understanding the distribution of human commensal organisms such as Aedes aegypti. The ecology of Aedes aegypti, the principal vector of dengue viruses in the tropics and subtropics, is linked to its almost obligatory association with humans. A better and more complete understanding of this phenomenon requires careful analysis of environmental factors, both mosquito and human, which have allowed for Aedes aegypti re-emergence in the desert southwest of the United States. This is the first comprehensive ecological assessment of factors contributing to the re-emergence of Aedes aegypti in three locales along the U.S.-Mexico border: Tucson, AZ; Nogales, AZ and Nogales, MX. Our objectives were to: analyze long-term regional climate variations and variability relevant to the mosquito's life cycle at the study sites; assess human housing characteristics and socio-economic factors that could affect mosquito density and increase the likelihood of human-vector contact; quantitatively evaluate presence/absence of Aedes aegypti through oviposition traps; and develop a web-based system for delivering study results of factors contributing to Aedes aegypti population density in arid urban and suburban areas. In this paper, we present an analysis of the climate, human behavioral, and ecological factors that are linked to the recolonization of this desert environment by Aedes aegypti. Interestingly, a more nuanced understanding of the contingent influence of climatic variables on the spatio-temporal dynamics of the Aedes aegypti in arid environments emerges. These ecological associations may help us better understand further re-colonizations of Aedes aegypti in other regions of the desert southwest.