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-
Butte-
Calaveras-
Colusa-
Contra Costa-
Del Norte-
El Dorado-
Fresno-
Glenn-
Humboldt-
Imperial-
Inyo-
Kern-
Kings-
Lake-
Lassen-
Los Angeles1
Madera-
Marin-
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange1
Placer-
Plumas-
Riverside-
Sacramento4
San Benito-
San Bernardino-
San Diego1
San Francisco-
San Joaquin-
San Luis Obispo-
San Mateo1
Santa Barbara-
Santa Clara-
Santa Cruz-
Shasta-
Sierra-
Siskiyou-
Solano-
Sonoma-
Stanislaus-
Sutter-
Tehama-
Trinity-
Tulare-
Tuolumne-
Ventura-
Yolo-
Yuba-
Total8

WNV Activity by County
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2017 | 2016 | 2015 | 2014
2013 | 2012 | 2011
2010 | 2009 | 2008
2007

Press Releases

CDPH Reports Increased West Nile Virus Activity Statewide

Jul 22, 2016

SACRAMENTO - The California Department of Public Health (CDPH) is reporting increased West Nile virus activity across the state and is investigating numerous suspect cases in humans. While the first human case has not been confirmed by CDPH, a resident of Los Angeles County has symptoms consistent with West Nile virus disease. Initial tests on that patient indicate a probable West Nile virus diagnosis, which requires further testing for confirmation.

"Californians should take every possible precaution to avoid mosquito bites," said CDPH Director and State Public Health Officer Dr. Karen Smith. "Simple steps, like applying repellent, wearing long-sleeved shirts and pants in the early morning and evening, and draining standing water near your home can help to prevent bites from infected mosquitos."

To date in 2016, West Nile virus has been detected in mosquitoes and birds in 30 California counties. Approximately 600 dead birds and 896 mosquito pools sampled in California this year have been found to harbor the virus.

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 one 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 indicate that people with diabetes and/or hypertension are at greatest risk for serious illness.

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 mosquitoes from biting. DEET can be used safely on infants and children two 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 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 or drain all sources of standing water around homes and properties, including buckets, old car tires, rain gutters, birdbaths, and pet bowls. If a swimming pool is not being properly maintained, please contact the 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 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 May 26, 2017201720165Y AVG
Counties91110
Human cases100
Dead birds85331
Mosquito samples122720
Sentinel chickens000
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2016 YTD activity -

WNV Reports

Weekly Report

05.26 Arbovirus Bulletin #8
05.26 2017 YTD WNV Activity Map
05.19 Arbovirus Bulletin #7

Humans

02.08 2016 Human WNV Incidence Report
02.08 2003-2016 WNV Case Summary
03.21 2015 Human WNV Incidence Report

Dead Birds

05.26Positive Counts by City/County for 2017
05.26Positive Species for 2017
05.26Reported, Tested, Positive 2017

Mosquitoes

05.26 AMOR - EVS Week 20
05.26 AMOR - GRAVID Week 20
05.26 AMOR - NJLT Week 20
- view report archives -