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Title: Spatially explicit West Nile virus risk modeling in Santa Clara County, California

Author
item KONRAD, SARAH - UNIVERSITY OF WYOMING
item MILLER, SCOTT - UNIVERSITY OF WYOMING
item Reeves, Will
item TIETZE, NOOR - SANTA CLARA COUNTY

Submitted to: Vector-Borne and Zoonotic Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2009
Publication Date: 6/9/2009
Citation: Konrad, S.K., Miller, S.N., Reeves, W.K., Tietze, N.S. 2009. Spatially explicit West Nile virus risk modeling in Santa Clara County, California. Vector-Borne and Zoonotic Diseases. 9(3):267-274.

Interpretive Summary: West Nile virus is a mosquito transmitted virus that can cause disease in humans and animals. Predicting the start of West Nile transmission season is helpful in protecting humans and animals from disease. We used a previously described computer based predictive model of West Nile virus with new data from California. Our model was predictive based on the temperature that West Nile virus requires for transmission. Risk of virus transmission was calibrated with data from infected birds collected in Santa Clara County, California. Once our model was calibrated with minor modifications based on temperature data and bird data from California, we validated it with field data. Our temperature based model was successful in predicting risk of West Nile transmission.

Technical Abstract: A previously created Geographic Information Systems model designed to identify regions of West Nile virus (WNV) transmission risk is tested and calibrated in Santa Clara County, California. American Crows that died from WNV infection in 2005 provide the spatial and temporal ground truth. Model parameters include degree-days until the mosquito vector reaches one extrinsic incubation period, length of vector feeding period, and minimum temperature below which the virus is not viable in the vector. The model run with parameters based on a laboratory study of Culex tarsalis mosquitoes infected with the NY99 genotype poorly estimates WNV risk in Santa Clara Co. The parameters are adjusted to fit the data by taking into account the replacement of NY99 with the WN02 genotype. The calibrated model can be used to predict present and future WNV risk in Santa Clara Co., and similar calibrations will help identify WNV risk in other regions.