Case Counts by County

CountyDead birds
Alameda2
Alpine-
Amador-
Butte1
Calaveras-
Colusa-
Contra Costa-
Del Norte-
El Dorado1
Fresno-
Glenn1
Humboldt-
Imperial-
Inyo-
Kern-
Kings1
Lake-
Lassen-
Los Angeles2
Madera1
Marin1
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange1
Placer-
Plumas-
Riverside5
Sacramento5
San Benito-
San Bernardino-
San Diego35
San Francisco-
San Joaquin1
San Luis Obispo-
San Mateo3
Santa Barbara-
Santa Clara22
Santa Cruz-
Shasta2
Sierra-
Siskiyou-
Solano1
Sonoma2
Stanislaus4
Sutter3
Tehama-
Trinity-
Tulare12
Tuolumne-
Ventura1
Yolo3
Yuba2
Total112

WNV Activity by County
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2015 | 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 previous year and previous five-year average to date

As of Jul 02, 2015201520145Y AVG
Counties312118
Human cases021
Dead birds112325138
Mosquito samples240234144
Sentinel chickens311
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2014 YTD activity -

WNV Reports

Weekly Report

07.02 Arbovirus Bulletin #18
07.02 2015 YTD WNV Activity Map
06.30 2015 US Arboviral Activity Update

Humans

04.02 2003-2014 WNV Case Summary
03.09 2014 Human WNV Incidence Report
08.12 2013 Human WNV Incidence Report

Dead Birds

07.02Positive Species for 2015
07.02Positive Counts by City/County for 2015
07.02Reported, Tested, Positive 2015

Mosquitoes

07.02 AMOR - EVS Week 25
07.02 AMOR - GRAVID Week 25
07.02 AMOR - NJLT Week 25
- view report archives -