Meteorological Factors Limit Aedes aegypti Longevity and Dengue Virus Transmission in the Sonoran Desert

Incidence of dengue fever (DF) have increased in the Americas during recent decades. However, despite the ubiquitous presence of a primary mosquito vector, levels of transmission vary substantially across Sonora, Mexico. Many studies have demonstrated that weather influences dengue virus transmission by regulating vector development rates, vector habitat availability, and the duration of the virus extrinsic incubation period (EIP). The EIP, the period between mosquito infection and the ability for it to re-transmit the virus, is especially important given its high sensitivity to temperature and the short lifespan of mosquitoes. Other studies, however, have suggested that human related factors such as socioeconomic status may explain much of the disparity in dengue incidence in this region. Using a meteorologically driven model of vector population dynamics and virus transmission we compare simulations of dengue fever cases in Sonora Mexico. A Monte Carlo approach is employed to select parameter values by evaluating simulations in Hermosillo, Mexico with reported dengue fever case data. Simulations that replicate the case data best are retained and rerun using remotely sensed climate data from Nogales, Mexico to determine the relative influence of weather on virus transmission. Simulations using Nogales weather data did not produce any cases of DF in 2008 and only a couple of cases in 2010 despite large outbreaks occurring in Hermosillo. Model results show that the mosquito populations were lower and the EIP was considerably longer in Nogales due to lower temperatures (~5-7°C). We reran the model with Nogales meteorological data with 1°C warming and observed a greater number of cases in 2010 but still no cases in 2008. This data suggests that although human factors undoubtedly influence dengue transmission in the Sonoran Desert, weather can be a major facilitator or disruptor of the transmission process.