Case Counts by County

CountyDead birds
Alameda19
Alpine-
Amador-
Butte38
Calaveras-
Colusa3
Contra Costa11
Del Norte-
El Dorado4
Fresno3
Glenn4
Humboldt2
Imperial-
Inyo-
Kern1
Kings3
Lake5
Lassen-
Los Angeles103
Madera1
Marin3
Mariposa-
Mendocino-
Merced3
Modoc-
Mono-
Monterey-
Napa7
Nevada10
Orange83
Placer21
Plumas-
Riverside82
Sacramento103
San Benito-
San Bernardino25
San Diego355
San Francisco-
San Joaquin18
San Luis Obispo-
San Mateo23
Santa Barbara3
Santa Clara231
Santa Cruz-
Shasta16
Sierra-
Siskiyou-
Solano10
Sonoma11
Stanislaus14
Sutter16
Tehama-
Trinity2
Tulare23
Tuolumne-
Ventura26
Yolo61
Yuba6
Total1349

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

Press Releases

CALIFORNIA DEPARTMENT OF PUBLIC HEALTH ANNOUNCES FIRST CONFIRMED HUMAN WEST NILE VIRUS CASE IN 2008

Jun 20, 2008

NUMBER: PH08-34
FOR RELEASE: IMMEDIATE
CONTACT: Suanne Buggy or Lea Brooks
http://www.cdph.ca.gov        
(916) 440-7259


SACRAMENTO - Dr. Mark Horton, director of the California Department of Public Health (CDPH), today announced that a Tulare County woman has tested positive for West Nile virus (WNV) infection, the first reported human case in California this year. She was not hospitalized and is recovering.

"The first human West Nile virus infection of 2008 underscores the importance of taking precautions to protect from mosquito bites," Horton said. "Californians should use insect repellent and eliminate all sources of standing water that can support mosquito breeding."

To date this year, WNV activity has been detected in 19 of California's 58 counties. In 2007, the first human case in California was reported on June 20th.

WNV is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds.

Most individuals who are infected with WNV will not experience any illness. Individuals 50 years of age and older have a higher chance of getting sick and are more likely to develop serious symptoms when infected with WNV. Recent data also indicate that those with diabetes and/or hypertension are at greatest risk for serious illness.

The most effective ways for individuals to prevent exposure to mosquito bites and WNV are:


  • DEET - Apply inspect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR 3535 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.

  • DAWN AND DUSK - Mosquitoes that carry WNV 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 or commercially available products to eliminate mosquito larvae.

California's WNV Web site - http://www.westnile.ca.gov - includes the latest information on WNV activity in the state. In order to help identify WNV activity, Californians are encouraged to report all dead birds and dead tree squirrels on the Web site 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 Dec 30, 2015201520145Y AVG
Counties414032
Human cases737801362
Dead birds134924421205
Mosquito samples332933402161
Sentinel chickens449443372
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2014 YTD activity -

WNV Reports

Weekly Report

01.12 2015 US Arboviral Activity Update
01.12 2015 YTD WNV Activity Map
12.18 Arbovirus Bulletin #41

Humans

01.06 2015 Human WNV Incidence Report
01.06 2003-2015 WNV Case Summary
03.09 2014 Human WNV Incidence Report

Dead Birds

01.12Positive Species for 2015
01.12Positive Counts by City/County for 2015
01.12Reported, Tested, Positive 2015

Mosquitoes

11.16 AMOR - EVS Week 44
11.16 AMOR - GRAVID Week 44
11.16 AMOR - NJLT Week 44
- view report archives -