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

Case Counts by County

CountyDead birds
Alameda10
Alpine-
Amador-
Butte1
Calaveras-
Colusa-
Contra Costa3
Del Norte-
El Dorado2
Fresno-
Glenn-
Humboldt1
Imperial-
Inyo-
Kern-
Kings-
Lake-
Lassen-
Los Angeles4
Madera-
Marin-
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange1
Placer19
Plumas-
Riverside3
Sacramento181
San Benito-
San Bernardino-
San Diego-
San Francisco-
San Joaquin7
San Luis Obispo-
San Mateo2
Santa Barbara-
Santa Clara26
Santa Cruz2
Shasta-
Sierra-
Siskiyou-
Solano-
Sonoma-
Stanislaus1
Sutter3
Tehama-
Trinity-
Tulare-
Tuolumne-
Ventura-
Yolo19
Yuba-
Total285

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 2018: 33

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

Reporting a Dead Bird Video


CDPH Confirms First Human West Nile Virus Illnesses of 2018
SACRAMENTO - The California Department of Public Health (CDPH) announced today the first confirmed illnesses in California due to West Nile virus (WNV). The four illnesses occurred in Los Angeles, Kern and Riverside Counties. "West Nile virus activity in the state is increasing, so I urge Californians to take every possible precaution to protect against mosquito bites," said CDPH Director and State Public Health Officer Dr. Karen Smith.

- view news and press release archives -

human cases

YTD: 19 Counties: 11
There were 7 new WNV human cases reported in California last week from the following counties: Los Angeles (2), San Joaquin (2), Stanislaus (1), Tuolumne (1), and Ventura (1). This is the first WNV human case from Stanislaus County this year. This is the first indication of WNV from Tuolumne and Ventura counties this year.

19 human cases from 11 counties have tested positive for WNV in 2018.

 

horses

YTD: 0 Counties: 0
No horses have tested positive for WNV in 2018.
 

dead birds

YTD: 285 Counties: 17
There were 57 new WNV positive dead birds reported in California last week from the following counties: Contra Costa (2), Los Angeles (1), Orange (1), Placer (5), Sacramento (39), San Joaquin (2), Santa Clara (1), and Yolo (6). This is the first WNV positive dead bird from Orange County this year.

285 dead birds from 17 counties have tested positive for WNV in 2018.

 

mosquito samples

YTD: 942 Counties: 26
There were 268 new WNV positive mosquito samples reported in California last week from the following counties: Butte (16), Contra Costa (2), Fresno (10), Glenn (1), Imperial (1), Kern (4), Kings (7), Lake (1), Los Angeles (10), Madera (5), Merced (1), Orange (7), Placer (39), Sacramento (50), San Bernardino (1), San Diego (1), San Joaquin (72), Santa Clara (2), Stanislaus (9), Sutter (3), Tulare (4), Yolo (18), and Yuba (4). This is the first indication of WNV from Glenn and Imperial counties this year.

942 mosquito samples from 26 counties have tested positive for WNV in 2018.

A mosquito sample may contain up to 50 individual mosquitoes.

 

sentinel chickens

YTD: 38 Counties: 8
There were 24 new WNV positive sentinel chickens reported in California last week from the following counties: Butte (11), Merced (7), San Benito (1), and Sutter (5). These are the first WNV positive sentinel chickens from Butte, Merced, and Sutter counties this year. This is the first indication of WNV from San Benito County this year.

38 sentinel chickens from 8 counties have tested positive for WNV in 2018.

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.

2003-2017 WNV Activity Summary

Element 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 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) 6,582 (292)
Horses 12 540 456 58 28 32 18 19 15 22 23 153 193 213 21 1,288
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 21,952
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 29,652
Sentinel chickens 70 809 1,053 640 510 585 443 281 391 540 485 443 449 343 305 7,347
Squirrels - 49 48 32 26 32 10 24 24 23 03 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 Aug 10, 2018201820175Y AVG
Counties333136
Human cases192232
Dead birds285172657
Mosquito samples94218051679
Sentinel chickens3858113
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2018 YTD activity -

WNV Reports

Weekly Report

08.13 2018 YTD SLEV Activity Map
08.13 2018 YTD WNV Activity Map
08.10 Arbovirus Bulletin #19

Humans

08.09 2018 Human WNV Incidence Report
08.09 2003-2018 WNV Case Summary
03.29 2017 Human WNV Incidence Report

Dead Birds

08.10Reported, Tested, Positive 2018
08.10Positive Species for 2018
08.10Positive Counts by City/County for 2018

Mosquitoes

08.10 AMOR - EVS Week 31
08.10 AMOR - GRAVID Week 31
08.10 AMOR - NJLT Week 31
- view report archives -