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

Case Counts by County

CountyDead birds
Alameda2
Alpine-
Amador-
Butte5
Calaveras-
Colusa1
Contra Costa19
Del Norte-
El Dorado2
Fresno5
Glenn2
Humboldt1
Imperial-
Inyo-
Kern3
Kings1
Lake4
Lassen-
Los Angeles93
Madera1
Marin1
Mariposa-
Mendocino-
Merced1
Modoc-
Mono-
Monterey1
Napa-
Nevada1
Orange52
Placer3
Plumas-
Riverside40
Sacramento86
San Benito-
San Bernardino45
San Diego35
San Francisco1
San Joaquin6
San Luis Obispo2
San Mateo1
Santa Barbara1
Santa Clara8
Santa Cruz1
Shasta2
Sierra-
Siskiyou-
Solano4
Sonoma5
Stanislaus6
Sutter3
Tehama-
Trinity-
Tulare8
Tuolumne-
Ventura1
Yolo14
Yuba6
Total473

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

Data on this website is updated every Friday by 4pm. Due to different reporting schedules, case totals on this website may not always be consistent with those reported by local health departments.
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 2016: 47

New counties highlighted in red.
Alameda, Butte, Calaveras, Colusa, Contra Costa, El Dorado, Fresno, Glenn, Humboldt, Imperial, Inyo, Kern, Kings, Lake, Lassen, Los Angeles, Madera, Marin, Merced, Monterey, Nevada, Orange, Placer, Plumas, Riverside, Sacramento, San Benito, San Bernardino, San Diego, San Francisco, San Joaquin, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Shasta, Solano, Sonoma, Stanislaus, Sutter, Tehama, Tulare, Tuolumne, Ventura, Yolo, and Yuba.

WNV Dead Bird Hotline Update
The West Nile virus and Dead Bird Hotline is staffed with live operators from mid-April to mid-October each year. During the winter months, you can still report a dead bird by using the report form on this website:

Report a Dead Bird

Although West Nile virus testing is reduced in the winter, some local vector control districts are collecting and testing birds year-round, especially crows, ravens, and magpies.

Thank you for your report!

- view news and press release archives -

human cases

YTD: 361 Counties: 23
There were 46 new WNV human cases reported in California last week from the following counties: Butte (1), Imperial (1), Los Angeles (26), Orange (2), Riverside (4), San Bernardino (4), San Diego (1), San Joaquin (2), Shasta (1), Stanislaus (3), and Ventura (1). These are the first WNV human cases from Shasta and Ventura counties this year.

18 WNV-related fatalities have been reported to CDPH this year from five local health jurisdictions: Kern (1), Long Beach (1), Los Angeles (10), Orange (1), San Bernardino (2), Stanislaus (1), and Yolo (2).

361 human cases from 23 counties have tested positive for WNV in 2017.

 

horses

YTD: 19 Counties: 12
There was 1 new WNV positive horse reported in California last week from Tuolumne County. This is the first indication of WNV from Tuolumne County this year.

19 horses from 12 counties have tested positive for WNV in 2017.

 

dead birds

YTD: 473 Counties: 39
There were 10 new WNV positive dead birds reported in California last week from the following counties: Alameda (1), Contra Costa (1), Los Angeles (2), San Diego (2), Santa Barbara (1), Solano (2), and Yolo (1). This is the first WNV positive dead bird from Santa Barbara County this year.

473 dead birds from 39 counties have tested positive for WNV in 2017.

 

mosquito samples

YTD: 3,304 Counties: 26
There were 13 new WNV positive mosquito samples reported in California last week from the following counties: Kern (1), Los Angeles (6), Riverside (1), Sacramento (2), Ventura (1), and Yolo (2).

3,304 mosquito samples from 26 counties have tested positive for WNV in 2017.

A mosquito sample may contain up to 50 individual mosquitoes.

 

sentinel chickens

YTD: 295 Counties: 18
There were 8 new WNV positive sentinel chickens reported in California last week from the following counties: Calaveras (1), Los Angeles (6), and Sutter (1). This is the first indication of WNV from Calaveras County this year.

295 sentinel chickens from 18 counties have tested positive for WNV in 2017.

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.

2003-2016 WNV Activity Summary

Element 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 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) 6,029 (248)
Horses 12 540 456 58 28 32 18 19 15 22 13 03 03 03 1,202
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 21,442
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 26,281
Sentinel chickens 70 809 1,053 640 510 585 443 281 391 540 485 443 449 343 7,042
Squirrels - 49 48 32 26 32 10 24 24 23 03 03 03 03 276
1 There were 20 imported human cases. 2 There were 3 imported horse cases. 3 No longer monitored.

Having problems with mosquitoes?

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

As of Oct 20, 2017201720165Y AVG
Counties473840
Human cases361346394
Dead birds47313321527
Mosquito samples330434563027
Sentinel chickens295329413
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2016 YTD activity -

WNV Reports

Weekly Report

10.20 Arbovirus Bulletin #29
10.20 2017 YTD SLEV Activity Map
10.20 2017 YTD WNV Activity Map

Humans

10.18 2017 Human WNV Incidence Report
10.18 2003-2017 WNV Case Summary
02.08 2016 Human WNV Incidence Report

Dead Birds

10.20Positive Counts by City/County for 2017
10.20Positive Species for 2017
10.20Reported, Tested, Positive 2017

Mosquitoes

10.20 AMOR - EVS Week 41
10.20 AMOR - GRAVID Week 41
10.20 AMOR - NJLT Week 41
- view report archives -