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

Case Counts by County

CountyDead birds
Alameda8
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-
Placer2
Plumas-
Riverside2
Sacramento67
San Benito-
San Bernardino-
San Diego-
San Francisco-
San Joaquin1
San Luis Obispo-
San Mateo2
Santa Barbara-
Santa Clara13
Santa Cruz1
Shasta-
Sierra-
Siskiyou-
Solano-
Sonoma-
Stanislaus1
Sutter-
Tehama-
Trinity-
Tulare-
Tuolumne-
Ventura-
Yolo6
Yuba-
Total108

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

Data on this website are updated every Friday by 4pm. Due to different reporting schedules, case totals here may not always reflect those reported by local health departments. Updates during the off season (January-April) are less frequent.
April 17 - 23 is West Nile and Mosquito and Vector Control Awareness Week in California! This week highlights the importance of preventing mosquito bites and protecting Californians from mosquito-borne diseases. Stop by the "Fight the Bite" event at the State Capitol in Sacramento on Thursday, April 21st from 1:00 - 4:00pm for more information. Contact your local mosquito and vector control district to learn about events in your area.

Interactive Map

View the interactive map courtesy of http://maps.calsurv.org
- View Printable Map -

Total Counties with
WNV in 2018: 24

New counties highlighted in red.
Alameda, Butte, Contra Costa, El Dorado, Fresno, Humboldt, Kern, Los Angeles, Madera, Merced, Orange, Placer, Riverside, Sacramento, San Bernardino, San Joaquin, San Mateo, Santa Clara, Santa Cruz, Shasta, Stanislaus, Sutter, Tulare, and Yolo.

CDPH Confirms First Human West Nile Virus Illnesses of 2018
SACRAMENTO - The California Department of Public Health (CDPH) announced today the first confirmed illnesses in California due to West Nile virus (WNV). The four illnesses occurred in Los Angeles, Kern and Riverside Counties. "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.

WNV Dead Bird Hotline Update
The West Nile virus and Dead Bird Hotline is staffed with live operators from 8AM to 4:30PM, Monday through Friday (later we will also be staffed on Sundays). Call the hotline at 1-877-WNV-BIRD to report a dead bird. Or fill out an online report form here:

Report a Dead Bird

Hotline operators will determine if the bird meets criteria for pickup and testing They will arrange for suitable dead birds to be picked up by a local vector control or public health agency for West Nile virus testing. Dead bird reports are very important because they are usually the first indication that the virus is active in an area, and this allows CDPH and local agencies to monitor the virus and implement control measures throughout the year.

Thank you for your report!

- view news and press release archives -

human cases

YTD: 10 Counties: 6
There was 1 new WNV human case reported in California last week from Fresno County.

10 human cases from 6 counties have tested positive for WNV in 2018.

 

horses

YTD: 0 Counties: 0
No horses have tested positive for WNV in 2018.
 

dead birds

YTD: 108 Counties: 13
There were 41 new WNV positive dead birds reported in California this week from the following counties: Alameda (1), Placer (1), Sacramento (31), Santa Clara (7), and Yolo (1).

108 dead birds from 13 counties have tested positive for WNV in 2018.

 

mosquito samples

YTD: 315 Counties: 20
There were 144 new WNV positive mosquito samples reported in California this week from the following counties: Butte (4), Contra Costa (2), Fresno (11), Kern (2), Madera (2), Placer (9), Riverside (2), Sacramento (66), San Joaquin (34), Shasta (2), Sutter (5), and Yolo (5). These are the first WNV positive mosquito samples from Contra Costa and Fresno counties this year. This is the first indication of WNV from Madera, Shasta, and Sutter counties this year.

315 mosquito samples from 20 counties have tested positive for WNV in 2018.

A mosquito sample may contain up to 50 individual mosquitoes.

 

sentinel chickens

YTD: 7 Counties: 1
There were 7 new WNV positive sentinel chickens reported in California last week from Contra Costa County. This is the first indication of WNV from Contra Costa County this year.

7 sentinel chickens from 1 county have tested positive for WNV in 2018.

Be a West Nile Watcher

Help us track down the West Nile Virus by reporting all dead birds. You can submit an online report by clicking on the button on the right.

2003-2017 WNV Activity Summary

Element 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Total
Human cases (fatal) 31 (0) 779 (29) 880 (19) 278 (7) 380 (21) 445 (15) 112 (4) 111 (6) 158 (9) 479 (20) 379 (15) 801 (31) 782 (53) 442 (19) 553 (44) 6,582 (292)
Horses 12 540 456 58 28 32 18 19 15 22 13 03 03 03 21 1,223
Dead birds 96 3,232 3,046 1,446 1,396 2,569 515 416 688 1,644 1,251 2,442 1,349 1,352 510 21,952
Mosquito samples 32 1,136 1,242 832 1,007 2,003 1,063 1,305 2,087 2849 2,528 3,340 3,329 3,528 3,371 29,652
Sentinel chickens 70 809 1,053 640 510 585 443 281 391 540 485 443 449 343 305 7,347
Squirrels - 49 48 32 26 32 10 24 24 23 03 03 03 03 03 276
1 There were 20 imported human cases. 2 There were 3 imported horse cases. 3 No longer monitored.

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

As of Jul 20, 2018201820175Y AVG
Counties242531
Human cases1044
Dead birds10890387
Mosquito samples315895827
Sentinel chickens72127
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2018 YTD activity -

WNV Reports

Weekly Report

07.20 ARbovirus Bulletin #16
07.20 2018 YTD SLEV Activity Map
07.20 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

07.20Reported, Tested, Positive 2018
07.20Positive Species for 2018
07.20Positive Counts by City/County for 2018

Mosquitoes

07.20 AMOR - EVS Week 28
07.20 AMOR - GRAVID Week 28
07.20 AMOR - NJLT Week 28
- view report archives -