West Nile Virus Activity Data Table Updated 03/20/2025 2024 Alameda County WNV activity2023 Alameda County WNV activity2021 Alameda County WNV activity2020 Alameda County WNV activity2018 Alameda County WNV activity2017 Alameda County WNV activity2016 Alameda County WNV activity2015 Alameda County WNV activityCalifornia West Nile virus activityNational West Nile virus information