Aedes aegypti mosquitoes are the primary vector for dengue, yellow fever and chikungunya. The vector is present in most urban communities stretching along the U.S.-Mexico border yet dengue transmission has only been noted in two U.S. border communities in Texas, notably Brownsville and Laredo, TX. While many argue that this is a result of different social factors across the border, this fails to explain the lack of transmission in some communities in northern Mexico, notably Nogales, Sonora. Nogales is a large urban area on the Mexican side of the border with large vector populations and a constant influx of people from dengue endemic areas yet no local cases have been recorded. Vector presence alone is not sufficient to cause disease transmission;vectors must also survive long enough to blood feed and become infected, have the parasite develop and feed again, transmitting the virus. Climatic influences on the lifespan and behavior of Ae. aegypti may also influence the risk of dengue transmission in this region which lies at the boundary of both virus and vector. Geographic areas such as this, at the edge of the range of disease and vector, are at greatest risk of emergence and reemergence of infectious diseases. We will assess the relative age structure of Ae. aegypti populations in nine cities with varying climates in the southern United States and Sonora, MX by trapping and molecularly determining the ages of adult Ae. aegypti during four mosquito seasons. We expect that cities with extremely dry and hot conditions will have younger Ae. aegypti populations. Cities with reported dengue transmission we expect to have Ae. aegypti that are on average younger when taking their first blood meal than cities without transmission. To determine how the age of Ae. aegypti population vary over a finer spatial scale, we will sample adults in 150 households in Hermosillo, Mexico;a city with a history of dengue outbreaks. Additionally, we will survey the households for potential social and environmental factors that mediate the relationship between climate and longevity. We expect to find significant variability across households. Residences with older mosquitoes will have more vegetation, fewer barriers to mosquito access and indoor resting sites, no competing vector species and no control measures. From the information gathered in the first two objectives, we will construct a model to predict the likelihood of the expansion of Ae. aegypti populations that survive long enough to transmit dengue and thus changes in risk of dengue transmission. We expect that models of risk of dengue under climate change scenarios will decrease in areas that surpass a heat and dryness threshold and will increase in populations with increasing moisture.

Public Health Relevance

This study will advance understanding related to the impact of climate change on the possible emergence of dengue in the southern United States and northern Mexico. A key outcome will be a broader understanding of how climatic changes would impact the longevity of the Aedes aegypti mosquito, a critical component of disease transmission. Risk maps will be generated that depict changes in density of vector's capable of transmission and length of mosquito season.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI091843-02
Application #
8534020
Study Section
Vector Biology Study Section (VB)
Program Officer
Costero, Adriana
Project Start
2012-09-01
Project End
2016-08-31
Budget Start
2013-09-01
Budget End
2014-08-31
Support Year
2
Fiscal Year
2013
Total Cost
$498,543
Indirect Cost
$132,528
Name
University of Arizona
Department
Public Health & Prev Medicine
Type
Schools of Public Health
DUNS #
806345617
City
Tucson
State
AZ
Country
United States
Zip Code
85721
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Walker, Kathleen R; Williamson, Daniel; Carrière, Yves et al. (2018) Socioeconomic and Human Behavioral Factors Associated With Aedes aegypti (Diptera: Culicidae) Immature Habitat in Tucson, AZ. J Med Entomol 55:955-963
Reyes-Castro, Pablo A; Harris, Robin B; Brown, Heidi E et al. (2017) Spatio-temporal and neighborhood characteristics of two dengue outbreaks in two arid cities of Mexico. Acta Trop 167:174-182
Ernst, Kacey C; Walker, Kathleen R; Reyes-Castro, Pablo et al. (2017) Aedes aegypti (Diptera: Culicidae) Longevity and Differential Emergence of Dengue Fever in Two Cities in Sonora, Mexico. J Med Entomol 54:204-211
Reyes-Castro, Pablo A; Castro-Luque, Lucía; Díaz-Caravantes, Rolando et al. (2017) Outdoor spatial spraying against dengue: A false sense of security among inhabitants of Hermosillo, Mexico. PLoS Negl Trop Dis 11:e0005611
Monaghan, Andrew J; Morin, Cory W; Steinhoff, Daniel F et al. (2016) On the Seasonal Occurrence and Abundance of the Zika Virus Vector Mosquito Aedes Aegypti in the Contiguous United States. PLoS Curr 8:
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Dickinson, Katherine L; Hayden, Mary H; Haenchen, Steven et al. (2016) Willingness to Pay for Mosquito Control in Key West, Florida and Tucson, Arizona. Am J Trop Med Hyg 94:775-9
Morin, Cory W; Monaghan, Andrew J; Hayden, Mary H et al. (2015) Meteorologically Driven Simulations of Dengue Epidemics in San Juan, PR. PLoS Negl Trop Dis 9:e0004002
Ernst, Kacey C; Haenchen, Steven; Dickinson, Katherine et al. (2015) Awareness and support of release of genetically modified ""sterile"" mosquitoes, Key West, Florida, USA. Emerg Infect Dis 21:320-4

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