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

Case Counts by County

CountyDead birds
Alameda1
Alpine-
Amador-
Butte5
Calaveras-
Colusa1
Contra Costa18
Del Norte-
El Dorado2
Fresno5
Glenn2
Humboldt1
Imperial-
Inyo-
Kern3
Kings1
Lake4
Lassen-
Los Angeles91
Madera1
Marin1
Mariposa-
Mendocino-
Merced1
Modoc-
Mono-
Monterey1
Napa-
Nevada1
Orange52
Placer3
Plumas-
Riverside40
Sacramento86
San Benito-
San Bernardino45
San Diego33
San Francisco1
San Joaquin6
San Luis Obispo2
San Mateo1
Santa Barbara-
Santa Clara8
Santa Cruz1
Shasta2
Sierra-
Siskiyou-
Solano2
Sonoma5
Stanislaus6
Sutter3
Tehama-
Trinity-
Tulare8
Tuolumne-
Ventura1
Yolo13
Yuba6
Total463

WNV Activity by County
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2007

Press Releases

CDPH Confirms First Human West Nile Virus Illness of 2017

Apr 28, 2017


SACRAMENTO - The California Department of Public Health (CDPH) announced the first confirmed illness in California due to West Nile virus (WNV). The illness occurred in Kings County.

"West Nile virus activity in the state is increasing, so I urge Californians to take every possible precaution to protect against mosquito bites", said CDPH Director and State Public Health Officer Dr. Karen Smith.

This year to date, West Nile virus activity has been detected in three dead birds, one each from San Mateo, Orange, and San Diego counties. Heavy rains this winter in California have contributed to an increase in mosquito breeding sites. It is not known what impact the wet weather may have on the actual virus transmission risk in humans. So far this season, West Nile activity is within expected levels.
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 West Nile immunity in birds. 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 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 Oct 13, 2017201720165Y AVG
Counties453840
Human cases315326356
Dead birds46313251499
Mosquito samples329134482986
Sentinel chickens287324400
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2016 YTD activity -

WNV Reports

Weekly Report

10.13 Arbovirus Bulletin #28
10.13 2017 YTD SLEV Activity Map
10.13 2017 YTD WNV Activity Map

Humans

10.11 2017 Human WNV Incidence Report
10.11 2003-2017 WNV Case Summary
02.08 2016 Human WNV Incidence Report

Dead Birds

10.13Positive Counts by City/County for 2017
10.13Positive Species for 2017
10.13Reported, Tested, Positive 2017

Mosquitoes

10.13 AMOR - EVS Week 40
10.13 AMOR - GRAVID Week 40
10.13 AMOR - NJLT Week 40
- view report archives -