Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2020
Year To Date (Weeks 1 - 53)

(2021-01-24) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda37811787%
Alpine22150%
Amador4---
Butte4812433%
Calaveras1---
Colusa1---
Contra Costa501612236%
Del Norte----
El Dorado3113--
Fresno19416531%
Glenn1---
Humboldt72--
Imperial1---
Inyo----
Kern91--
Kings9---
Lake127--
Lassen----
Los Angeles86320010251%
Madera16---
Marin323133%
Mariposa----
Mendocino2---
Merced735240%
Modoc----
Mono1---
Monterey194--
Napa133133%
Nevada242--
Orange5492254721%
Placer1385735%
Plumas2---
Riverside1503126%
Sacramento7093189129%
San Benito2---
San Bernardino6711--
San Diego19711111%
San Francisco516--
San Joaquin15938411%
San Luis Obispo162--
San Mateo2448511%
Santa Barbara234--
Santa Clara48615275%
Santa Cruz7918--
Shasta201--
Sierra----
Siskiyou----
Solano8328311%
Sonoma627--
Stanislaus17812433%
Sutter3711--
Tehama5---
Trinity----
Tulare5412542%
Tuolumne11--
Ventura6118--
Yolo211882933%
Yuba251--
State Totals5851168534320%

* 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