Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2021
Year To Date (Weeks 1 - 18)

(2021-05-11) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda105---
Alpine----
Amador2---
Butte5---
Calaveras2---
Colusa1---
Contra Costa1261--
Del Norte----
El Dorado213--
Fresno162--
Glenn1---
Humboldt----
Imperial----
Inyo----
Kern123--
Kings5---
Lake21--
Lassen----
Los Angeles1668--
Madera3---
Marin15---
Mariposa----
Mendocino----
Merced9---
Modoc----
Mono----
Monterey1---
Napa91--
Nevada61--
Orange170129--
Placer396--
Plumas----
Riverside255--
Sacramento15842--
San Benito3---
San Bernardino306--
San Diego4219--
San Francisco62--
San Joaquin38---
San Luis Obispo5---
San Mateo11542--
Santa Barbara193--
Santa Clara18628--
Santa Cruz23---
Shasta11---
Sierra----
Siskiyou1---
Solano183--
Sonoma28---
Stanislaus32---
Sutter7---
Tehama----
Trinity1---
Tulare16---
Tuolumne----
Ventura172--
Yolo392--
Yuba1---
State Totals153730900%

* 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