CA Dept. of Public Health UC Davis Arbovirus Research and Training Mosquito and Vector Control Assoc. of CA

Case Counts by County

CountyDead birds
Alameda1
Alpine-
Amador-
Butte-
Calaveras-
Colusa-
Contra Costa-
Del Norte-
El Dorado-
Fresno4
Glenn-
Humboldt-
Imperial-
Inyo-
Kern-
Kings-
Lake-
Lassen-
Los Angeles12
Madera-
Marin-
Mariposa-
Mendocino-
Merced2
Modoc-
Mono-
Monterey-
Napa1
Nevada-
Orange4
Placer-
Plumas-
Riverside1
Sacramento42
San Benito-
San Bernardino-
San Diego-
San Francisco-
San Joaquin1
San Luis Obispo-
San Mateo-
Santa Barbara-
Santa Clara5
Santa Cruz-
Shasta-
Sierra-
Siskiyou-
Solano1
Sonoma-
Stanislaus4
Sutter-
Tehama-
Trinity-
Tulare1
Tuolumne-
Ventura-
Yolo2
Yuba-
Total81

WNV Activity by County
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2020 | 2019 | 2018
2017 | 2016 | 2015
2014 | 2013 | 2012
2011 | 2010 | 2009
2008 | 2007

Press Releases

CDPH Confirms First Two Human West Nile Virus Deaths of 2018

Sep 10, 2018

SACRAMENTO - The California Department of Public Health (CDPH) announced today two confirmed deaths in California due to West Nile virus (WNV). The deceased persons were residents of Glenn county and Yuba county.

"We are still in a peak period of West Nile virus transmission in the state so we urge everyone to take every possible precaution to protect themselves against mosquito bites," said CDPH Director and State Health Officer Dr. Karen Smith.

As of September 7, CDPH has reported 56 human cases of WNV from 21 California counties this year. Additionally, 422 dead birds from 18 counties have tested positive for WNV in 2018, and 1,606 mosquito samples from 28 counties have also tested positive for WNV this year.

West Nile virus is influenced by many factors, including climate, the number and types of birds and mosquitoes in an area, and the level of WNV immunity in birds. West Nile virus is transmitted to humans and animals by the bite of an infected mosquito. The risk of serious illness to most people is low. However, some individuals - less than one percent - can develop serious neurologic illnesses such as encephalitis or meningitis.

People 60 years of age and older and individuals with diabetes or hypertension have a higher chance of getting sick, and are more likely to develop complications.

CDPH recommends that individuals protect against mosquito bites and WNV by practicing the "Three Ds":

1. DEET - Apply insect repellent containing DEET, picaridin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. Insect repellents should not be used on children under two months of age.

2. DAWN AND DUSK - Mosquitoes that transmit West Nile Virus usually bite in the early morning and evening so it is important to wear proper clothing and repellent if outside during these times. Make sure your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens that have tears or holes.

3. DRAIN - Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property by emptying flower pots, old car tires, buckets, and other containers. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.

California's West Nile virus website includes the latest information on WNV activity in the state. Californians are encouraged to report dead birds on the website or by calling toll-free 1-877-WNV-BIRD (968-2473).

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Compared to previous year and previous five-year average to date

As of Aug 07, 2020202020195Y AVG
Counties272332
Human cases101024
Dead birds8158370
Mosquito samples67516441638
Sentinel chickens211069
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2020 YTD activity -

WNV Reports

Weekly Report

08.07 2020 YTD SLEV Activity Map
08.07 2020 YTD WNV Activity Map
07.31 Arbobulletin #16

Humans

08.07 2020 Human WNV Incidence Report
08.07 2003-2020 WNV Case Summary
03.02 2019 Human WNV Incidence Report

Dead Birds

08.07Reported, Tested, Positive 2020
08.07Positive Species for 2020
08.07Positive Counts by City/County for 2020

Mosquitoes

10.04 AMOR - EVS Week 39
10.04 AMOR - GRAVID Week 39
10.04 AMOR - NJLT Week 39
- view report archives -