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

Case Counts by County

CountyDead birds
Alameda-
Alpine-
Amador-
Butte-
Calaveras-
Colusa-
Contra Costa-
Del Norte-
El Dorado-
Fresno8
Glenn-
Humboldt-
Imperial-
Inyo-
Kern1
Kings-
Lake-
Lassen-
Los Angeles7
Madera-
Marin-
Mariposa-
Mendocino-
Merced2
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange11
Placer1
Plumas-
Riverside-
Sacramento16
San Benito-
San Bernardino-
San Diego1
San Francisco-
San Joaquin3
San Luis Obispo-
San Mateo-
Santa Barbara-
Santa Clara-
Santa Cruz-
Shasta-
Sierra-
Siskiyou-
Solano-
Sonoma-
Stanislaus-
Sutter-
Tehama-
Trinity-
Tulare15
Tuolumne-
Ventura-
Yolo-
Yuba2
Total67

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 2019: 25

New counties highlighted in red.
Butte, Fresno, Glenn, Imperial, Kern, Kings, Lake, Los Angeles, Madera, Merced, Orange, Placer, Riverside, Sacramento, San Bernardino, San Diego, San Joaquin, Shasta, Solano, Stanislaus, Sutter, Tulare, Ventura, Yolo, and Yuba.

Increasing West Nile Virus Activity in California
SACRAMENTO - The California Department of Public Health (CDPH) urges all Californians to protect themselves from mosquito bites during West Nile virus (WNV) season, which extends from now through early fall.

Reporting a Dead Bird Video


- view news and press release archives -

human cases

YTD: 14 Counties: 9
There were 4 new WNV human cases reported in California last week from the following counties: Butte (1), San Joaquin (1), Solano (1), and Tulare (1). These are the first WNV human cases from Butte and San Joaquin counties this year. This is the first indication of WNV from Solano County this year.

1 WNV-related fatality has been reported to CDPH this year from a single local health jurisdiction: Imperial County (1).

14 human cases from 9 counties have tested positive for WNV in 2019.

 

horses

YTD: 2 Counties: 2
There have been 2 new WNV positive horses reported in California last week from Kern (1) and Stanislaus (1) counties. These are the first WNV positive horses from Kern and Stanislaus counties this year.

2 horses from 2 counties have tested positive for WNV in 2019.

 

dead birds

YTD: 67 Counties: 11
There were 9 new WNV positive dead birds reported in California last week from the following counties: Kern (1), Los Angeles (1), Merced (1), Placer (1), Sacramento (4), and Tulare (1). These are the first WNV positive dead birds from Kern and Placer counties this year.

67 dead birds from 11 counties have tested positive for WNV in 2019.

 

mosquito samples

YTD: 1,988 Counties: 23
There were 341 new WNV positive mosquito samples reported in California last week from the following counties: Butte (16), Fresno (43), Glenn (1), Kern (13), Kings (12), Lake (1), Los Angeles (5), Madera (10), Merced (1), Orange (2), Placer (13), Riverside (7), Sacramento (6), San Bernardino (14), San Joaquin (63), Stanislaus (46), Sutter (6), Tulare (68), Yolo (9), and Yuba (5). This is the first indication of WNV from Glenn County this year.

1,988 mosquito samples from 23 counties have tested positive for WNV in 2019.

A mosquito sample may contain up to 50 individual mosquitoes.

 

sentinel chickens

YTD: 26 Counties: 6
There were 16 new WNV positive sentinel chickens reported in California last week from the following counties: Los Angeles (4), Merced (1), Placer (4), and Tulare (7). These are the first WNV positive sentinel chickens from Placer and Tulare counties this year.

26 sentinel chickens from 6 counties have tested positive for WNV in 2019.

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.

2003-2018 WNV Activity Summary

Element 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 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) 217 (11) 6,799 (303)
Horses 12 540 456 58 28 32 18 19 15 22 23 153 193 213 21 11 1,299
Dead birds 96 3,232 3,046 1,446 1,396 2,569 515 416 688 1,644 1,251 2,442 1,349 1,352 510 501 22,093
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 1,963 31,615
Sentinel chickens 70 809 1,053 640 510 585 443 281 391 540 485 443 449 343 305 163 7,510
Squirrels - 49 48 32 26 32 10 24 24 23 03 03 03 03 03 03 276
1 There were 20 imported human cases. 2 There were 3 imported horse cases. 3 Not monitored this year.

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

As of Aug 16, 2019201920185Y AVG
Counties253436
Human cases142155
Dead birds67316690
Mosquito samples198811191906
Sentinel chickens2644115
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2019 YTD activity -

WNV Reports

Weekly Report

08.20 2019 YTD WNV Activity Map
08.16 Arbobulletin #20
08.16 2019 YTD SLEV Activity Map

Humans

08.16 2019 Human WNV Incidence Report
08.16 2003-2019 WNV Case Summary
05.15 2018 Human WNV Incidence Report

Dead Birds

08.20Positive Counts by City/County for 2019
08.20Positive Species for 2019
08.20Reported, Tested, Positive 2019

Mosquitoes

08.16 AMOR - EVS Week 32
08.16 AMOR - GRAVID Week 32
08.16 AMOR - NJLT Week 32
- view report archives -