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-
Butte4
Calaveras-
Colusa1
Contra Costa10
Del Norte-
El Dorado1
Fresno5
Glenn2
Humboldt1
Imperial-
Inyo-
Kern3
Kings1
Lake3
Lassen-
Los Angeles59
Madera1
Marin-
Mariposa-
Mendocino-
Merced1
Modoc-
Mono-
Monterey1
Napa-
Nevada1
Orange37
Placer2
Plumas-
Riverside29
Sacramento65
San Benito-
San Bernardino37
San Diego22
San Francisco1
San Joaquin6
San Luis Obispo-
San Mateo1
Santa Barbara-
Santa Clara7
Santa Cruz1
Shasta2
Sierra-
Siskiyou-
Solano2
Sonoma2
Stanislaus4
Sutter2
Tehama-
Trinity-
Tulare8
Tuolumne-
Ventura1
Yolo6
Yuba6
Total336

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: 42

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

CDPH Confirms First Human West Nile Virus Deaths of 2017
SACRAMENTO - The California Department of Public Health (CDPH) announced today three confirmed deaths in California due to West Nile virus (WNV). The deceased persons were residents of Kern, Los Angeles and San Bernardino counties. CDPH is unable to provide additional patient details including demographic information and name of hospital providing care to protect confidentiality.

Reporting a Dead Bird Video


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human cases

YTD: 143 Counties: 15
There were 35 new WNV human cases reported in California last week from the following counties: Fresno (1), Inyo (2), Kern (1), Los Angeles (19), Orange (3), Riverside (2), San Bernardino (3), San Joaquin (3), and Stanislaus (1).

6 WNV-related fatalities have been reported to CDPH this year from 4 local health jurisdictions in 3 counties: Kern (1), Long Beach (1), Los Angeles (3), and San Bernardino (1).

143 human cases from 15 counties have tested positive for WNV in 2017.

 

horses

YTD: 13 Counties: 9
There were 3 new WNV positive horses reported in California last week from the following counties: Riverside (2), and Tehama (1). This is the first indication of WNV from Tehama County this year.

13 horses from 9 counties have tested positive for WNV in 2017.

 

dead birds

YTD: 336 Counties: 36
There were 38 new WNV positive dead birds reported in California last week from the following counties: Contra Costa (3), Fresno (1), Glenn (2), Humboldt (1), Lake (1), Los Angeles (8), Madera (1), Orange (4), Placer (1), Riverside (1), Sacramento (5), San Bernardino (3), San Diego (4), Shasta (1), Solano (1), and Yolo (1). These are the first WNV positive dead birds from Glenn and Madera counties this year. This is the first indication of WNV from Humboldt County this year.

336 dead birds from 36 counties have tested positive for WNV in 2017.

 

mosquito samples

YTD: 2,979 Counties: 25
There were 161 new WNV positive mosquito samples reported in California last week from the following counties: Butte (3), Contra Costa (1), Fresno (5), Inyo (1), Kern (1), Lake (1), Los Angeles (34), Madera (2), Orange (20), Placer (11), Riverside (5), Sacramento (16), San Bernardino (11), San Joaquin (18), Solano (1), Sonoma (1), Stanislaus (13), Tulare (15), and Yolo (2). This is the first WNV positive mosquito sample from Sonoma County this year.

2,979 mosquito samples from 25 counties have tested positive for WNV in 2017.

A mosquito sample may contain up to 50 individual mosquitoes.

 

sentinel chickens

YTD: 204 Counties: 13
There were 15 new WNV positive sentinel chickens reported in California last week from the following counties: Butte (4), Los Angeles (1), Placer (2), Solano (2), and Sutter (6). This is the first WNV positive sentinel chicken from Placer County this year.

204 sentinel chickens from 13 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.

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

As of Sep 15, 2017201720165Y AVG
Counties423638
Human cases143199183
Dead birds33612381262
Mosquito samples297931902633
Sentinel chickens204280301
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2016 YTD activity -

WNV Reports

Weekly Report

09.19 2017 US Arboviral Activity Update
09.18 2017 YTD WNV Activity Map
09.15 Arbovirus Bulletin #24

Humans

09.13 2017 Human WNV Incidence Report
09.13 2003-2017 WNV Case Summary
02.08 2016 Human WNV Incidence Report

Dead Birds

09.18Positive Counts by City/County for 2017
09.18Positive Species for 2017
09.18Reported, Tested, Positive 2017

Mosquitoes

09.15 AMOR - EVS Week 36
09.15 AMOR - GRAVID Week 36
09.15 AMOR - NJLT Week 36
- view report archives -