GH010-13
An 18-Year Retrospective Analysis of West Nile Virus Infection in Culex Mosquitoes of the Midwestern United States
Monday, 14 December 2020: 10:36
Virtual
Johnny Albert Uelmen Jr1, Bo Li2, William M. Brown3, Surendra Karki1, Marilyn Ruiz2, Sadie Ryan4, Jonathan A. Patz5 and Rebecca L. Smith3, (1)University of Illinois at Urbana Champaign, Pathobiology, Urbana, IL, United States, (2)University of Illinois at Urbana Champaign, Urbana, IL, United States, (3)University of Illinois at Urbana Champaign, Pathobiology, Urbana, United States, (4)University of Florida, Geography, Ft Walton Beach, FL, United States, (5)University of Wisconsin Madison, Nelson Institute for Environmental Studies / Center for Sustainability & the Global Environment / Global Health Institute / Population Health Sciences, Madison, WI, United States
Abstract:
Background: West Nile Virus (WNV) has been in the United States (U.S.) for over two decades, resulting in more than 50,000 human illness cases and 2,330 deaths. Now the cause for the most widespread mosquito-borne illness in humans, numerous efforts to model WNV transmission have been attempted, with widespread and sometimes conflicting, interpretation of results. With increases in accessibility of detailed, historical data, information sharing, and collaboration across multiple partners and states, this study collated and analyzed several large mosquito abundance and infection datasets from 16 partners in the Midwestern U.S. The main goal is to create a single standardized record of mosquito infection and abundance across time and space in a large region of the U.S. to effectively compare and contrast key model parameters and to generate robust forecasts under anticipated future shifts in climate.
Methods: All available records of female Culex spp. abundance and infection records, from 2000 to 2018, were provided by 118 counties, representing 8 states in the Midwest U.S. All datasets were organized, screened for redundancies and erroneous entries, and collated. In total, over 6.6 million mosquitoes were collected, and over 4.7 million were tested for WNV. These data were compiled to create standardized minimum infection rate (MIR) and vector index (VI) by county by month for each year. Serving as the dependent variables, MIR and VI were assessed in one of four model scenarios, with 60 explanatory variables consisting of climatic, socio-economic and demographic, and land-use/land-cover available.
Results: The vast majority of models (under any scenario) for most counties performed well (R2 > 0.85 and RMSE < 1.5). The strongest models for each county generally correlated strongly with human neuroinvasive cases. Counties with the highest resources did not generally result in higher overall mosquito infection.
Conclusions: Although most locations were predicted well, nearly all of Iowa and Southern Wisconsin did not have models that correlated well with human neuroinvasive cases, suggesting knowledge gaps in environmental viral presence, particularly among rural counties. This 18-year assessment showed an annual increase in MIR by 16.4% and estimates the next outbreak year for human cases to be in 2022-2023.
