Case Counts by County

CountyDead birds
Alameda5
Alpine-
Amador-
Butte17
Calaveras-
Colusa3
Contra Costa2
Del Norte-
El Dorado1
Fresno-
Glenn3
Humboldt2
Imperial-
Inyo-
Kern1
Kings1
Lake2
Lassen-
Los Angeles3
Madera1
Marin1
Mariposa-
Mendocino-
Merced1
Modoc-
Mono-
Monterey-
Napa-
Nevada1
Orange5
Placer4
Plumas-
Riverside16
Sacramento27
San Benito-
San Bernardino1
San Diego65
San Francisco-
San Joaquin7
San Luis Obispo-
San Mateo7
Santa Barbara-
Santa Clara49
Santa Cruz-
Shasta3
Sierra-
Siskiyou-
Solano4
Sonoma3
Stanislaus8
Sutter10
Tehama-
Trinity1
Tulare18
Tuolumne-
Ventura2
Yolo23
Yuba4
Total301

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

Human data is updated every Friday by 4pm. Dead bird data is updated every Wednesday and Friday by 4pm. Mosquito and sentinel chicken data are updated on Fridays by 4pm.

Due to different reporting schedules, case totals on this website may not always be consistent with those reported by local health departments.

Interactive Map

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

Total Counties with
WNV in 2015: 36

New counties highlighted in red.
Alameda, Butte, Colusa, Contra Costa, El Dorado, Fresno, Glenn, Humboldt, Kern, Kings, Lake, Los Angeles, Madera, Marin, Merced, Nevada, Orange, Placer, Riverside, Sacramento, San Bernardino, San Diego, San Joaquin, San Mateo, Santa Barbara, Santa Clara, Shasta, Solano, Sonoma, Stanislaus, Sutter, Trinity, Tulare, Ventura, Yolo, and Yuba.

CDPH Confirms First Human West Nile Virus Death of 2015
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 Nevada County.
- view news and press release archives -

human cases

YTD: 8 Counties: 5
There were 7 new WNV human cases reported in California last week from the following counties: Butte (3), Glenn (1), Los Angeles (1), and Tulare (2). These are the first WNV human cases from Butte, Glenn, Los Angeles, and Tulare counties this year.

1 WNV-related fatality has been reported to CDPH from one local health jurisdiction: Nevada (1).

8 human cases from 5 counties have tested positive for WNV in 2015.

 

dead birds

YTD: 301 Counties: 34
There were 54 new WNV positive dead birds reported in California last week from the following counties: Butte (9), Humboldt (1), Lake (2), Los Angeles (1), Nevada (1), Placer (3), Riverside (7), Sacramento (6), San Diego (3), San Joaquin (1), San Mateo (3), Santa Clara (4), Sonoma (1), Sutter (1), Trinity (1), Tulare (2), Ventura (1), and Yolo (7). These are the first WNV positive dead birds from Lake and Nevada counties this year. This is the first indication of WNV from Trinity County this year.

301 dead birds from 34 counties have tested positive for WNV in 2015.

 

mosquito samples

YTD: 1,058 Counties: 27
There were 302 new WNV positive mosquito samples reported in California last week from the following counties: Butte (22), Fresno (1), Kern (43), Kings (12), Lake (1), Los Angeles (4), Merced (1), Placer (15), Riverside (6), Sacramento (13), San Joaquin (26), San Mateo (2), Santa Clara (1), Shasta (14), Sonoma (3), Stanislaus (3), Sutter (7), Tulare (88), Yolo (37), and Yuba (3). This is the first WNV positive mosquito sample from San Mateo County this year.

1,058 mosquito samples from 27 counties have tested positive for WNV in 2015.

 

sentinel chickens

YTD: 45 Counties: 9
There have been 2 new WNV positive sentinel chickens reported in California last week from Los Angeles (1) and Placer (1) counties. This is the first WNV positive sentinel chicken from Los Angeles County this year.

45 sentinel chickens from 9 counties have tested positive for WNV in 2015.

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.

2003-2014 WNV Activity Summary

Element 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 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) 4,805 (176)
Horses 12 540 456 58 28 32 18 19 15 22 13 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 18,741
Mosquito samples 32 1,136 1,242 832 1,007 2,003 1,063 1,305 2,087 2849 2,528 3,340 19,424
Sentinel chickens 70 809 1,053 640 510 585 443 281 391 540 485 443 6,250
Squirrels - 49 48 32 26 32 10 24 24 23 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 31, 2015201520145Y AVG
Counties363527
Human cases8187
Dead birds301875386
Mosquito samples1058977641
Sentinel chickens453938
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2014 YTD activity -

WNV Reports

Weekly Report

07.31 Arbovirus Bulletin #22
07.31 2015 YTD WNV Activity Map
07.28 2015 US Arboviral Activity Update

Humans

07.29 2015 Human WNV Incidence Report
07.29 2003-2015 WNV Case Summary
03.09 2014 Human WNV Incidence Report

Dead Birds

07.31Positive Species for 2015
07.31Positive Counts by City/County for 2015
07.31Reported, Tested, Positive 2015

Mosquitoes

07.31 AMOR - EVS Week 29
07.31 AMOR - GRAVID Week 29
07.31 AMOR - NJLT Week 29
- view report archives -