Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2023
Year To Date (Weeks 1 - 53)

(2024-05-27) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda5051588051%
Alpine----
Amador2---
Butte7218211%
Calaveras5---
Colusa104250%
Contra Costa5561319573%
Del Norte----
El Dorado5917424%
Fresno13810110%
Glenn3---
Humboldt10---
Imperial2---
Inyo1---
Kern162--
Kings14---
Lake2516850%
Lassen----
Los Angeles8121284434%
Madera291218%
Marin504250%
Mariposa3---
Mendocino182--
Merced412--
Modoc----
Mono4---
Monterey161--
Napa2910440%
Nevada176117%
Orange1694325%
Placer2761464329%
Plumas----
Riverside2651136961%
Sacramento94145619643%
San Benito82150%
San Bernardino119251144%
San Diego213961415%
San Francisco6815--
San Joaquin152432047%
San Luis Obispo341218%
San Mateo348841518%
Santa Barbara1610--
Santa Clara64219911759%
Santa Cruz4412--
Shasta256233%
Sierra----
Siskiyou1---
Solano123421843%
Sonoma177251664%
Stanislaus16515640%
Sutter5111655%
Tehama7---
Trinity----
Tulare5213538%
Tuolumne3---
Ventura9125416%
Yolo3401326751%
Yuba263--
State Totals6793204985742%

* Birds in a die-off are not included in reported totals because the deaths are not related to WNV. A die-off is defined as a group of 10 or more same species dead birds unless the species is American Crow.
Source: Vector-Borne Disease Section, California Department of Public Health