Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2023
Year To Date (Weeks 1 - 48)

(2023-12-04) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda491827895%
Alpine----
Amador2---
Butte7018211%
Calaveras5---
Colusa94250%
Contra Costa5461319573%
Del Norte----
El Dorado5617424%
Fresno13510110%
Glenn3---
Humboldt8---
Imperial2---
Inyo1---
Kern162--
Kings13---
Lake2416850%
Lassen----
Los Angeles8001284434%
Madera291218%
Marin474250%
Mariposa2---
Mendocino172--
Merced402--
Modoc----
Mono4---
Monterey161--
Napa2810440%
Nevada176117%
Orange1654325%
Placer2731464329%
Plumas----
Riverside2571136961%
Sacramento92345619643%
San Benito82150%
San Bernardino118251144%
San Diego20890910%
San Francisco6413--
San Joaquin150432047%
San Luis Obispo341218%
San Mateo333781418%
Santa Barbara1610--
Santa Clara62519811759%
Santa Cruz4012--
Shasta236233%
Sierra----
Siskiyou1---
Solano121421843%
Sonoma173251664%
Stanislaus16213646%
Sutter4711655%
Tehama7---
Trinity----
Tulare5112542%
Tuolumne3---
Ventura8825416%
Yolo3331326751%
Yuba253--
State Totals6629195584943%

* 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