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

Case Counts by County

CountyDead birds
Alameda-
Alpine-
Amador-
Butte1
Calaveras-
Colusa-
Contra Costa1
Del Norte-
El Dorado-
Fresno2
Glenn-
Humboldt-
Imperial-
Inyo-
Kern-
Kings-
Lake-
Lassen-
Los Angeles25
Madera1
Marin1
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange7
Placer-
Plumas-
Riverside1
Sacramento153
San Benito-
San Bernardino-
San Diego124
San Francisco-
San Joaquin9
San Luis Obispo-
San Mateo-
Santa Barbara-
Santa Clara19
Santa Cruz-
Shasta-
Sierra-
Siskiyou-
Solano1
Sonoma-
Stanislaus2
Sutter2
Tehama-
Trinity-
Tulare-
Tuolumne-
Ventura4
Yolo5
Yuba-
Total358

WNV Activity by County
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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).

Having problems with mosquitoes?

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 01, 2016201620155Y AVG
Counties213121
Human cases001
Dead birds358114153
Mosquito samples264180122
Sentinel chickens731
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2015 YTD activity -

WNV Reports

Weekly Report

07.01 2016 YTD WNV Activity Map
06.24 Arbovirus Bulletin #16
06.17 Arbovirus Bulletin #15

Humans

03.21 2015 Human WNV Incidence Report
03.21 2003-2015 WNV Case Summary
03.09 2014 Human WNV Incidence Report

Dead Birds

07.01Positive Species for 2016
07.01Reported, Tested, Positive 2016
07.01Positive Counts by City/County for 2016

Mosquitoes

06.24 AMOR - EVS Week 24
06.24 AMOR - GRAVID Week 24
06.24 AMOR - NJLT Week 24
- view report archives -