Dead Birds Reported, Tested, and Positive
for WNV by County in California in 2023
Year To Date (Weeks 1 - 22)

(2023-06-07) - Source: http://westnile.ca.gov

CountyReported*TestedPositive% Tested Positive
Alameda1106233%
Alpine----
Amador----
Butte217--
Calaveras----
Colusa2---
Contra Costa1876--
Del Norte----
El Dorado133--
Fresno544--
Glenn2---
Humboldt5---
Imperial1---
Inyo----
Kern72--
Kings1---
Lake2---
Lassen----
Los Angeles2592628%
Madera8---
Marin14---
Mariposa2---
Mendocino5---
Merced181--
Modoc----
Mono1---
Monterey6---
Napa81--
Nevada3---
Orange6618--
Placer4514--
Plumas----
Riverside449111%
Sacramento2498345%
San Benito4---
San Bernardino318--
San Diego8130--
San Francisco247--
San Joaquin5710--
San Luis Obispo142--
San Mateo11124--
Santa Barbara95--
Santa Clara18928725%
Santa Cruz192--
Shasta41--
Sierra----
Siskiyou----
Solano2710--
Sonoma27---
Stanislaus50---
Sutter132--
Tehama4---
Trinity----
Tulare132--
Tuolumne1---
Ventura193--
Yolo8319--
Yuba132--
State Totals1926335165%

* 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