Climate change is a known contributor to increasing human mortality and disease risk. Many of these risks are due to increased transmission of vector-borne diseases like malaria where climate change directly or indirectly affects the distribution of the pathogen and/or vector. Developing models that are capable of predicting changes in health risk involve being able to successfully model not just transmission and disease dynamics, but also vector biology and the impacts of ecological variation as a consequence of climate change. In Mexico, vampire bats (Desmodus rotundus) are the main vector for the transmission of rabies to domestic animals and humans. Because of its strict physiological limitations, the northward movement of this species should closely track the movement of the 10°C isotherm – the lowest winter temperatures that this species can tolerate. The average temperature along the Texas-Mexico border is likely to increase by 1.5-2.9°C by 2080, and up to a 4°C increase in parts of Texas. Field studies have revealed that Desmodus populations may be expanding in Mexico, including moving into higher elevations, similar to patterns seen in Costa Rica. Here we present a model that predicts future range expansion of the common vampire bat, Desmodus rotundus, over the next 75 years. We modeled the change in the 10°C isotherm under different climate change models (CCC, ECHAM and Hadley) and three model scenarios for the time periods of 2020, 2050 and 2080.
Results/Conclusions
Over the next few decades the 10°C isotherm, and thus the distribution of Desmodus, is predicted to expand significantly along the east and west coasts of Mexico, Baja California as well as the southern tip and gulf coast of Texas. Disjunct areas of suitable temperature are also predicted for southern parts of Florida and Arizona. Desmodus range size is expected to increase by at least a third of its current Mexico range, and as it extends higher in elevation will occupy almost the entire southern and coastal regions of Mexico along with areas of Texas, and possibly other southern states like Arizona and Louisiana. Given this increase in range in Mexico and the US, it is crucial that current and future rabies surveillance programs focus on the identified regions and proactive measures be taken in preparation for future changes.
