Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2026
Year To Date (Weeks 1 - 52)

(2026-03-29) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda52---
Alpine----
Amador----
Butte5---
Calaveras1---
Colusa1---
Contra Costa522--
Del Norte----
El Dorado4---
Fresno12---
Glenn----
Humboldt----
Imperial----
Inyo1---
Kern3---
Kings4---
Lake1---
Lassen----
Los Angeles134---
Madera----
Marin9---
Mariposa1---
Mendocino1---
Merced4---
Modoc----
Mono----
Monterey20---
Napa4---
Nevada1---
Orange39---
Placer24---
Plumas----
Riverside222--
Sacramento89---
San Benito----
San Bernardino15---
San Diego671517%
San Francisco11---
San Joaquin8---
San Luis Obispo27---
San Mateo7416--
Santa Barbara19---
Santa Clara54---
Santa Cruz22---
Shasta2---
Sierra----
Siskiyou----
Solano10---
Sonoma13---
Stanislaus10---
Sutter3---
Tehama----
Trinity1---
Tulare3---
Tuolumne1---
Ventura21---
Yolo37---
Yuba4---
State Totals8863513%

* 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