Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2021
Year To Date (Weeks 1 - 42)

(2021-10-28) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda2707723%
Alpine----
Amador6---
Butte3210220%
Calaveras4---
Colusa2---
Contra Costa3643638%
Del Norte1---
El Dorado378--
Fresno858--
Glenn4---
Humboldt1---
Imperial1---
Inyo1---
Kern274--
Kings9---
Lake64--
Lassen----
Los Angeles7061334332%
Madera62--
Marin382--
Mariposa1---
Mendocino5---
Merced312150%
Modoc----
Mono----
Monterey117--
Napa268--
Nevada207229%
Orange43933372%
Placer11450510%
Plumas----
Riverside9923--
Sacramento68840310025%
San Benito51--
San Bernardino1062614%
San Diego11761--
San Francisco298--
San Joaquin127541731%
San Luis Obispo248--
San Mateo27771--
Santa Barbara339--
Santa Clara4247811%
Santa Cruz6418--
Shasta191--
Sierra----
Siskiyou1---
Solano642428%
Sonoma949111%
Stanislaus11814214%
Sutter257114%
Tehama2---
Trinity1---
Tulare4514750%
Tuolumne21--
Ventura461318%
Yolo154701014%
Yuba203--
State Totals4831160720813%

* 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