Case Counts by County

CountyDead birds
Alameda8
Alpine-
Amador-
Butte1
Calaveras-
Colusa1
Contra Costa16
Del Norte-
El Dorado1
Fresno5
Glenn1
Humboldt-
Imperial-
Inyo-
Kern2
Kings-
Lake5
Lassen-
Los Angeles7
Madera3
Marin2
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa1
Nevada-
Orange31
Placer10
Plumas-
Riverside-
Sacramento112
San Benito-
San Bernardino2
San Diego-
San Francisco-
San Joaquin19
San Luis Obispo-
San Mateo1
Santa Barbara-
Santa Clara371
Santa Cruz1
Shasta2
Sierra-
Siskiyou-
Solano24
Sonoma6
Stanislaus14
Sutter11
Tehama-
Trinity-
Tulare31
Tuolumne-
Ventura1
Yolo16
Yuba3
Total708

WNV Activity by County
Printable Version
2014 | 2013 | 2012
2011 | 2010 | 2009
2008 | 2007

Press Releases

CDPH Reports First Human West Nile Virus Case of 2012

Jun 18, 2012

SACRAMENTO - A 70-year-old female in Kern County is the first confirmed human case of West Nile virus infection in California this year, announced Dr. Ron Chapman, state health officer and director of the California Department of Public Health (CDPH). The woman was hospitalized, but is now recovering.

"This first confirmed West Nile virus case reminds us that we must take precautions to protect ourselves and our families from mosquito bites," said Chapman. "West Nile virus activity is greatest during the summertime."

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 1 percent - can develop a serious neurologic illness such as encephalitis or meningitis. People 50 years of age and older have a higher chance of getting sick and are more likely to develop complications. Recent data also indicates that those with diabetes and/or hypertension are at greatest risk for serious illness.

To date in 2012, West Nile virus has been detected in 15 California counties.

CDPH recommends that individuals prevent exposure to mosquito bites and West Nile virus by practicing the "Three Ds":


  1. DEET - Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.
  2. DAWN AND DUSK - Mosquitoes bite in the early morning and evening so it is important to wear proper clothing and repellent if outside during these times. Make sure that your doors and windows have tight-fitting screens to keep mosquitoes out. Repair or replace screens with tears or holes.
  3. . DRAIN - Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, rain gutters and pet bowls. 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 West Nile virus activity in the state. Californians are encouraged to report all dead birds and dead tree squirrels on the website or by calling toll-free 1-877-WNV-BIRD (968-2473).

Locate Your Local Mosquito and Vector Control Agency
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Compared to 2013 YTD

As of Jul 22, 201420132014
Counties3133
Human cases415
Dead birds230708
Mosquito samples555771
Sentinel chickens2714
2013 YTD - Year to date corresponds to the same time last year.

- view all 2013 YTD activity -

WNV Reports

Weekly Report

07.22 2014 YTD WNV Activity Map
07.18 Arbovirus Bulletin #22
07.15 2014 US Arboviral Activity Update

Humans

07.21 2014 Human WNV Incidence Report
07.21 2003-2014 WNV Case Summary
04.21 2013 Human WNV Incidence Report

Dead Birds

07.22Reported, Tested, Positive 2014
07.22Positive Counts by City/County for 2014
07.22Positive Species for 2014

Mosquitoes

07.18 AMOR - EVS Week 28
07.18 AMOR - GRAVID Week 28
07.18 AMOR - NjLT Week 28

Horses

12.16 2010 Equine WNV Result Map
12.16 2010 Confirmed Equine Cases Report
05.26 2009 Equine WNV Result Map
- view report archives -