LAUSR

West Nile virus (WNV) (Orthoflavivirus nilense) and Saint Louis encephalitis virus (SLEV) (Orthoflavivirus louisense) are transmitted by Culex quinquefasciatus Say and Culex tarsalis Coquillett in Maricopa County, Arizona, where a significant increase in the number of WNV cases was reported in 2021. We used data collected between 2014 and 2021 from a network of CO2-baited surveillance traps to assess whether particular land use categories may have contributed to this rise in WNV cases. For each vector species and year, we estimated the association between the areas of each of 10 land use categories neighboring the traps and vector abundance or the odds of detecting WNV or SLEV in females from the traps. Across years, the percentage of traps detecting WNV in each vector was positively associated with the number of reported WNV human cases. Positive associations between areas of the land use categories Single-Family Residential, Industrial, and Golf Course and the odds of detecting WNV only occurred in 2021, indicating that a greater occurrence of WNV in vectors from within these land use categories may have contributed to the rise in WNV human cases in 2021. Areas of the land use categories Golf Course and Vacant were consistently negatively associated with Cx. quinquefasciatus abundance and the odds of detecting SLEV. Agriculture was consistently positively associated with Cx. tarsalis abundance and the odds of detecting SLEV. By identifying land use categories that may have mediated arbovirus transmission at landscape scale, our results provide valuable information for developing targeted vector control strategies.