Assessing the Impact of Climate on the Two Vectors of Chikungunya Virus and Dengue Fever in Brownsville, Texas

Chikungunya Virus is an emerging mosquito-borne virus which causes extreme joint pain that lasts for weeks and even months in some cases. In July of 2013, the United States saw its first local case of the virus and has since reported 11 autochthonous cases. As of August 7th, 2015, Mexico has confirmed 3,306 autochthonous cases of the virus. Even more concerning are the intermittent, locally-acquired outbreaks of Dengue Fever being reported in southern Texas. In 2005, a large scale outbreak of Dengue Fever occurred in the Brownsville/Matamoros area. Serology studies conducted during the outbreak show that 38% of the Brownsville population has been exposed to Dengue virus, meaning an increased risk for the more serious Dengue Hemorrhagic Fever that comes with secondary infection. The Chikungunya vectors, Aedes albopictus and Aedes aegypti, are the same vectors that transmit Dengue Fever and are well studied. Temperature, relative humidity, and rainfall have all been shown to affect the development of the two vectors differently in their varying stages of life. Both of these vectors are present in a large swath of the southeastern and south central United States, including Brownsville, Texas.

This study will assess the effect of changing climate in altering populations of the two mosquito vectors. Population modeling will be accomplished using Skeeter Buster, which uses temperature, rainfall, and relative humidity inputs as well as actual neighborhood housing/mosquito container data to output a dynamic and spatially explicit representation of Aedes aegypti populations. Downscaled climate data out to year 2100 for the city of Brownsville, Texas was obtained from the Climate Science Center at Texas Tech University. The climate data includes temperature, relative humidity, and precipitation predictions for the highest carbon forcing climate scenario (RCP8.5) and the second lowest carbon forcing climate scenario (RCP4.5). Within each of these scenarios, 7 climate model forecasts will be utilized in Skeeter Buster. Actual housing and container data from two neighborhoods in the city of Brownsville will also be input into the model to accurately represent the city. Results will provide Health Departments with information they can use to help mitigate the plausible threat that both Chikungunya Virus and Dengue Fever pose.