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

Case Counts by County

CountyDead birds
Alameda7
Alpine-
Amador-
Butte-
Calaveras-
Colusa-
Contra Costa-
Del Norte-
El Dorado2
Fresno-
Glenn-
Humboldt1
Imperial-
Inyo-
Kern-
Kings-
Lake-
Lassen-
Los Angeles2
Madera-
Marin-
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange-
Placer1
Plumas-
Riverside2
Sacramento36
San Benito-
San Bernardino-
San Diego-
San Francisco-
San Joaquin1
San Luis Obispo-
San Mateo2
Santa Barbara-
Santa Clara6
Santa Cruz1
Shasta-
Sierra-
Siskiyou-
Solano-
Sonoma-
Stanislaus1
Sutter-
Tehama-
Trinity-
Tulare-
Tuolumne-
Ventura-
Yolo5
Yuba-
Total67

WNV Activity by County
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2018 | 2017 | 2016 | 2015 | 2014
2013 | 2012 | 2011
2010 | 2009 | 2008
2007

Press Releases

CDPH Confirms First Human West Nile Virus Death of 2016

Aug 5, 2016

SACRAMENTO - California Department of Public Health (CDPH) Director and State Health Officer Dr. Karen Smith today announced the first confirmed death in California due to West Nile virus (WNV). The deceased person was a senior citizen in Sacramento County.

"West Nile virus can cause a deadly infection in humans, and the elderly are particularly susceptible, as this unfortunate fatality illustrates," said Dr. Smith. "West Nile virus activity in the state is increasing, so I urge Californians to take every possible precaution to protect themselves against mosquito bites."

CDPH has reported ten human cases of WNV from eight California counties this year. In addition, 764 dead birds from 26 counties have tested positive for WNV in 2016 and 1,487 mosquito samples from 30 counties have also tested positive for WNV this year.

The number of WNV positive dead birds and mosquito samples exceeds the numbers at this same time last year and are above the state's most recent five-year average.

West Nile virus is influenced by many factors, including climate, the number and types of birds and mosquitoes in an area and the level of WNV immunity in birds. West Nile 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 serious neurologic illnesses such as encephalitis or meningitis.

People 50 years of age and older and individuals with diabetes or hypertension have a higher chance of getting sick and are more likely to develop complications.

CDPH recommends that individuals protect against mosquito bites and WNV 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. Insect repellents should not be used on children under two months of age.

  2. DAWN AND DUSK - Mosquitoes usually 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 out mosquitoes. Repair or replace screens that have tears or holes.

  3. DRAIN - Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, by emptying flower pots, old car tires, buckets, and other containers. 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 WNV activity in the state. Californians are encouraged to report 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 Jul 13, 2018201820175Y AVG
Counties212228
Human cases1043
Dead birds6772307
Mosquito samples171681597
Sentinel chickens71712
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2018 YTD activity -

WNV Reports

Weekly Report

07.13 Arbovirus Bulletin #15
07.13 2018 YTD SLEV Activity Map
07.13 2018 YTD WNV Activity Map

Humans

07.12 2018 Human WNV Incidence Report
07.12 2003-2018 WNV Case Summary
03.29 2017 Human WNV Incidence Report

Dead Birds

07.13Reported, Tested, Positive 2018
07.13Positive Species for 2018
07.13Positive Counts by City/County for 2018

Mosquitoes

07.13 AMOR - EVS Week 27
07.13 AMOR - GRAVID Week 27
07.13 AMOR - NJLT Week 27
- view report archives -