Case Counts by County

CountyDead birds
Alameda13
Alpine-
Amador-
Butte1
Calaveras-
Colusa1
Contra Costa18
Del Norte-
El Dorado1
Fresno6
Glenn1
Humboldt-
Imperial-
Inyo-
Kern2
Kings-
Lake5
Lassen-
Los Angeles7
Madera3
Marin2
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa1
Nevada-
Orange43
Placer10
Plumas-
Riverside-
Sacramento112
San Benito-
San Bernardino2
San Diego1
San Francisco-
San Joaquin19
San Luis Obispo-
San Mateo3
Santa Barbara-
Santa Clara429
Santa Cruz1
Shasta2
Sierra-
Siskiyou-
Solano26
Sonoma6
Stanislaus14
Sutter11
Tehama-
Trinity-
Tulare31
Tuolumne-
Ventura1
Yolo16
Yuba3
Total791

WNV Activity by County
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2011 | 2010 | 2009
2008 | 2007

News

CDPH Reports First Human West Nile Virus Case of 2011

Jul 22, 2011

CONTACT: Al Lundeen or Melinda Beer (916) 440-7259

SACRAMENTO - The California Department of Public Health (CDPH) today reported a man in Santa Barbara County is the first confirmed human case of West Nile virus infection in California this year. The man was hospitalized, but is now recovering at home.

"With the first confirmed human illness from West Nile virus this year, we are intensifying our surveillance for the virus with the help of all counties," said CDPH Chief Deputy Director Kathleen Billingsley. "To protect against West Nile virus, the most important step people can take is avoiding mosquito bites."

West Nile virus is most commonly transmitted to humans and animals by the bite of a mosquito harboring the virus. The risk of serious illness to most people is low. However, some individuals - less than 1 percent - will develop 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 serious symptoms. Recent data also indicate that those with diabetes and/or hypertension are at greatest risk for serious illness.

To date in 2011, West Nile virus has been detected in 14 other California counties.

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

  • 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.
  • DRESS - Wear clothing that reduces the risk of skin exposure to mosquito bites.
  • DAWN AND DUSK - Mosquitoes bite in the early morning and evening so it is important to wear repellent at this time. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.
  • 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 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).

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

As of Jul 23, 201420132014
Counties3234
Human cases415
Dead birds325791
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

07.23 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
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04.21 2013 Human WNV Incidence Report

Dead Birds

07.23Reported, Tested, Positive 2014
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07.23Positive Species for 2014

Mosquitoes

07.18 AMOR - EVS Week 28
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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 -