Case Counts by County

CountyDead birds
Alameda5
Alpine-
Amador-
Butte8
Calaveras-
Colusa3
Contra Costa2
Del Norte-
El Dorado1
Fresno-
Glenn3
Humboldt1
Imperial-
Inyo-
Kern1
Kings1
Lake-
Lassen-
Los Angeles2
Madera1
Marin1
Mariposa-
Mendocino-
Merced1
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange5
Placer1
Plumas-
Riverside9
Sacramento21
San Benito-
San Bernardino1
San Diego65
San Francisco-
San Joaquin6
San Luis Obispo-
San Mateo6
Santa Barbara-
Santa Clara45
Santa Cruz-
Shasta3
Sierra-
Siskiyou-
Solano4
Sonoma2
Stanislaus8
Sutter9
Tehama-
Trinity-
Tulare18
Tuolumne-
Ventura1
Yolo16
Yuba4
Total254

WNV Activity by County
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2015 | 2014 | 2013
2012 | 2011 | 2010
2009 | 2008 | 2007

Press Releases

First California Fatality from West Nile Virus in 2012

Aug 3, 2012

SACRAMENTO - An 88-year-old woman from Kern County is the first reported fatality from West Nile virus (WNV) this year, Dr. Ron Chapman, director of the California Department of Public Health, announced today.

"This unfortunate death reminds us that we must protect ourselves from mosquito bites to prevent West Nile virus and other mosquito born infections," Chapman said. An increase in WNV activity has occurred earlier this year compared to last year, he added.

To date in 2012, ten human cases of WNV from five California counties have been reported. Last year at this time there were seven human cases and no deaths. During all of 2011, 159 human cases and nine fatalities were reported. Increased activity is also being seen in other parts of the United States. Nationwide, 241 human cases were reported to the Centers for Disease Control and Prevention as of August 1, 2012. This is the highest number of cases reported through the end of July since 2004.

WNV is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds. The risk of serious illness to most people is low. However, some individuals - less than 1 percent of those infected - will develop serious neurologic illness such as encephalitis or meningitis. Individuals 50 years of age and older have a higher chance of getting sick and are more likely to develop serious symptoms. Studies also show that those people with diabetes and/or hypertension are at greater risk for serious illness.

Chapman said California residents are very good at protecting themselves from mosquito bites for planned events like camping, however we tend to have a false sense of security in our own backyards. The most effective way for individuals to prevent exposure to mosquito bites and West Nile virus is to remember the "Three D's":

1. DEFEND - Use an EPA-registered insect repellent with DEET, picaridin, 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 that carry WNV bite in the early morning and evening. It is important to use repellent and wear clothing that reduces the risk of skin exposure to mosquito bites during this time. Make sure your doors and windows have tight-fitting screens to keep out mosquitoes. 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 buckets, old car tires, and pet bowls. If you have a pond, use mosquito fish (available from your local mosquito and vector control agency) or commercially available products to eliminate mosquito larvae.

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).

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

As of Jul 29, 2015201520145Y AVG
Counties353527
Human cases1135
Dead birds254875386
Mosquito samples756771477
Sentinel chickens431418
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2014 YTD activity -

WNV Reports

Weekly Report

07.29 2015 YTD WNV Activity Map
07.28 2015 US Arboviral Activity Update
07.24 Arbovirus Bulletin #21

Humans

07.24 2003-2015 WNV Case Summary
07.22 2015 Human WNV Incidence Report
03.09 2014 Human WNV Incidence Report

Dead Birds

07.29Positive Species for 2015
07.29Positive Counts by City/County for 2015
07.29Reported, Tested, Positive 2015

Mosquitoes

07.17 AMOR - EVS Week 27
07.17 AMOR - GRAVID Week 27
07.17 AMOR - NjLT Week 27
- view report archives -