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

Case Counts by County

CountyDead birds
Alameda11
Alpine-
Amador-
Butte21
Calaveras-
Colusa-
Contra Costa26
Del Norte-
El Dorado4
Fresno6
Glenn4
Humboldt-
Imperial-
Inyo-
Kern-
Kings4
Lake4
Lassen-
Los Angeles113
Madera5
Marin5
Mariposa-
Mendocino-
Merced5
Modoc-
Mono-
Monterey-
Napa1
Nevada2
Orange76
Placer27
Plumas-
Riverside14
Sacramento408
San Benito-
San Bernardino5
San Diego252
San Francisco-
San Joaquin35
San Luis Obispo-
San Mateo11
Santa Barbara-
Santa Clara85
Santa Cruz2
Shasta3
Sierra-
Siskiyou-
Solano11
Sonoma8
Stanislaus10
Sutter10
Tehama-
Trinity-
Tulare3
Tuolumne-
Ventura30
Yolo71
Yuba4
Total1276

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?

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

As of Sep 23, 2016201620155Y AVG
Counties374038
Human cases234233192
Dead birds12769691176
Mosquito samples324927692451
Sentinel chickens295314325
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2015 YTD activity -

WNV Reports

Weekly Report

09.23 Arbovirus Bulletin #29
09.23 2016 YTD WNV Activity Map
09.20 2016 US Arboviral Activity Update

Humans

09.14 2016 Human WNV Incidence Report
09.14 2003-2016 WNV Case Summary
03.21 2015 Human WNV Incidence Report

Dead Birds

09.23Positive Species for 2016
09.23Reported, Tested, Positive 2016
09.23Positive Counts by City/County for 2016

Mosquitoes

09.23 AMOR - EVS Week 37
09.23 AMOR - GRAVID Week 37
09.23 AMOR - NJLT Week 37
- view report archives -