Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2008
Year To Date (Weeks 1 - 25)

(2025-06-22) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda70655--
Alpine3---
Amador1108--
Butte7513213%
Calaveras12913--
Colusa46---
Contra Costa22279411%
Del Norte27---
El Dorado5432514%
Fresno123269--
Glenn924--
Humboldt782--
Imperial35---
Inyo353--
Kern159013011%
Kings1336--
Lake941--
Lassen23---
Los Angeles55352082512%
Madera12114--
Marin21916--
Mariposa182--
Mendocino796--
Merced20715--
Modoc17---
Mono11---
Monterey27211--
Napa88---
Nevada3051716%
Orange29961825832%
Placer7249--
Plumas578--
Riverside12693239%
Sacramento310614132%
San Benito342--
San Bernardino15545859%
San Diego17421164236%
San Francisco1057--
San Joaquin15097568%
San Luis Obispo18015--
San Mateo3894013%
Santa Barbara965--
Santa Clara96141410%
Santa Cruz1639--
Shasta40612542%
Sierra16---
Siskiyou211--
Solano5426--
Sonoma49545--
Stanislaus9385324%
Sutter1796233%
Tehama1378--
Trinity14---
Tulare754872225%
Tuolumne922--
Ventura55335--
Yolo53416--
Yuba1034--
State Totals34395174618310%

* 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