Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2009
Year To Date (Weeks 1 - 47)

(2021-12-01) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda414601017%
Alpine1---
Amador404125%
Butte381611321%
Calaveras443--
Colusa306233%
Contra Costa12211954523%
Del Norte11---
El Dorado28352917%
Fresno9771555938%
Glenn9520630%
Humboldt327--
Imperial30---
Inyo226--
Kern617862833%
Kings15228932%
Lake398225%
Lassen71--
Los Angeles20143788222%
Madera108211152%
Marin147---
Mariposa283--
Mendocino496--
Merced30325936%
Modoc138113%
Mono75--
Monterey14717424%
Napa915--
Nevada9617--
Orange862340103%
Placer4024948%
Plumas251--
Riverside36417212%
Sacramento14232032814%
San Benito265--
San Bernardino5241081716%
San Diego4531763922%
San Francisco831218%
San Joaquin5811122321%
San Luis Obispo1431816%
San Mateo1783713%
Santa Barbara637114%
Santa Clara628851416%
Santa Cruz1692115%
Shasta26648919%
Sierra----
Siskiyou61--
Solano2627343%
Sonoma230---
Stanislaus594842833%
Sutter634--
Tehama5114--
Trinity10---
Tulare392822530%
Tuolumne3311218%
Ventura2654137%
Yolo31044716%
Yuba171--
State Totals15822270551019%

* 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