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Environmental drivers of West Nile virus Symposium

Environmental drivers of West Nile virus Symposium

30 - Exploring the interplay between warming temperatures and future implications for West Nile virus transmission

Tuesday, March 4, 2025
2:03 PM – 2:15 PM AST
Location: 208 A
Abstract:

Background: Year-after-year, unprecedented warming temperatures brought forth by climate change have far-reaching impacts on ecosystems, evolution, and public health. One area of concern is the spread of arthropods and the diseases they transmit. Like all arthropods, a mosquito’s rate of development is mediated by external abiotic forces, namely temperature. In North America, West Nile virus (WNV) is the most widespread and important human mosquito-borne disease (MBD). Using three of the most competent WNV mosquito vector species, this study aims to evaluate the implications and evolutionary dynamics of WNV transmission under anticipated warming temperatures.


Methods: We applied temperature-sensitive projection models to each of the following three mosquito species’ thermal optimal thresholds (established by Shocket et al, 2020): Culex (Cx.) quinquefasciatus, Cx. tarsalis, and Cx. pipiens. Models were calculated from an ensemble of 8 General Circulation Models (GCMs) of the Coupled Model Intercomparison Project (CMIP6) included in the IPCC sixth assessment report (AR6). We applied these models to the “worst case scenario” emissions scenario, called “Shared Socioeconomic Pathways” (SSPs), SSP585 (minimal mitigation practices and continued fossil fuel extraction, resulting in a global surface temperature change of +8°C) and calculated average temperature projections for the following three time periods: 2020-2040, 2040-2060, and 2060-2080. To improve our projection estimates, we selected 25% of each species’ thermal optimum (±12.5%). Projected mosquito distributions were created in R and ArcGIS, using raster math, proximity overlays, and symmetrical difference calculations to estimate each pixel’s (4km x 4km resolution) corresponding value.

INTERPRETATIONS: Unequivocally, mosquitoes and other arthropod vectors will significantly gain territory within optimal thermal ranges. As temperatures warm, arthropods will become active earlier and for longer durations in newly expanded ranges, increasing risks of pathogen transmission to immunologically naïve populations. Endemic ranges were slightly reduced, but seasonal ranges significantly increased.