Case Counts by County

CountyDead birds
Alameda13
Alpine-
Amador-
Butte2
Calaveras-
Colusa1
Contra Costa19
Del Norte-
El Dorado1
Fresno7
Glenn1
Humboldt1
Imperial-
Inyo-
Kern2
Kings1
Lake5
Lassen-
Los Angeles9
Madera4
Marin2
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa5
Nevada-
Orange55
Placer16
Plumas-
Riverside-
Sacramento143
San Benito-
San Bernardino2
San Diego1
San Francisco-
San Joaquin23
San Luis Obispo-
San Mateo3
Santa Barbara-
Santa Clara429
Santa Cruz1
Shasta2
Sierra-
Siskiyou-
Solano27
Sonoma8
Stanislaus17
Sutter13
Tehama-
Trinity-
Tulare32
Tuolumne-
Ventura1
Yolo21
Yuba5
Total872

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

Human data is updated every Tuesday 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.
- View Printable Map -

Total Counties with
WNV in 2014: 35

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

CDPH Reports First Human West Nile Virus Infections This Season
SACRAMENTO - The first two human infections with West Nile virus this season have been reported by Contra Costa and San Joaquin Counties, announced Dr. Ron Chapman, director of the California Department of Public Health (CDPH) and state health officer. The patient from Contra Costa County has since recovered and been released from the hospital, and the patient from San Joaquin County has tested positive for the virus but is not showing symptoms at this time.
- view news and press release archives -

NOTE:

human cases

YTD: 15 Counties: 6
There were 4 new WNV human cases reported in California this week from the following counties: Fresno (2), Orange (1), and Stanislaus (1).

15 human cases from 6 counties have tested positive for WNV in 2014.

 

dead birds

YTD: 872 Counties: 33
There were 164 new WNV positive dead birds reported in California this week from the following counties: Alameda (5), Butte (1), Contra Costa (3), Fresno (2), Humboldt (1), Kings (1), Los Angeles (2), Madera (1), Napa (4), Orange (24), Placer (6), Sacramento (31), San Diego (1), San Joaquin (4), San Mateo (2), Santa Clara (58), Solano (3), Sonoma (2), Stanislaus (3), Sutter (2), Tulare (1), Yolo (5), and Yuba (2). This is the first WNV positive dead bird from Kings County this year. This is the first indication of WNV from Humboldt and San Diego counties this year.

872 dead birds from 33 counties have tested positive for WNV in 2014.

 

mosquito samples

YTD: 771 Counties: 27
There were 255 new WNV positive mosquito samples reported in California last week from the following counties: Alameda (1), Butte (8), Contra Costa (3), Fresno (19), Kern (8), Kings (20), Lake (5), Los Angeles (7), Madera (2), Merced (3), Orange (30), Placer (11), Riverside (3), Sacramento (34), San Bernardino (4), San Joaquin (12), Santa Clara (1), Shasta (1), Stanislaus (6), Sutter (7), Tulare (39), Yolo (26), and Yuba (5). These are the first WNV positive mosquito samples from Alameda and Butte counties this year. This is the first indication of WNV from Merced and Riverside counties this year.

771 mosquito samples from 27 counties have tested positive for WNV in 2014.

 

sentinel chickens

YTD: 14 Counties: 5
There were 5 new WNV positive sentinel chickens reported in California last week from the following counties: Merced (1), and San Bernardino (4). This is the first indication of WNV from Merced County this year.

14 sentinel chickens from 5 counties have tested positive for WNV in 2014.

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.

2003-2013 WNV Activity Summary

Element 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 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) 4,004 (145)
Horses 12 540 456 58 28 32 18 19 15 22 13 1,202
Dead birds 96 3,232 3,046 1,446 1,396 2,569 515 416 688 1,644 1,251 16,299
Mosquito samples 32 1,136 1,242 832 1,007 2,003 1,063 1,305 2,087 2849 2,528 16,084
Sentinel chickens 70 809 1,053 640 510 585 443 281 391 540 485 5,807
Squirrels - 49 48 32 26 32 10 24 24 23 8 276
1 There were 20 imported human cases. 2 There were 3 imported horse cases.

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Compared to 2013 YTD

As of Jul 23, 201420132014
Counties3235
Human cases415
Dead birds325872
Mosquito samples555771
Sentinel chickens2714
2013 YTD - Year to date corresponds to the same time last year.

- view all 2013 YTD activity -

WNV Reports

Weekly Report

07.25 2014 YTD WNV Activity Map
07.18 Arbovirus Bulletin #22
07.15 2014 US Arboviral Activity Update

Humans

07.21 2014 Human WNV Incidence Report
07.21 2003-2014 WNV Case Summary
04.21 2013 Human WNV Incidence Report

Dead Birds

07.25Reported, Tested, Positive 2014
07.25Positive Counts by City/County for 2014
07.25Positive Species for 2014

Mosquitoes

07.25 AMOR - EVS Week 29
07.25 AMOR - GRAVID Week 29
07.25 AMOR - NJLT Week 29

Horses

12.16 2010 Equine WNV Result Map
12.16 2010 Confirmed Equine Cases Report
05.26 2009 Equine WNV Result Map
- view report archives -