- Press Releases
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- Jul 09, 2021
West Nile virus (WNV) is a mosquito-borne virus that causes disease in humans, horses, and birds. WNV spreads to people through the bite of an infected mosquito, and it can make people sick and even cause death. WNV is common in the United States, especially in California, and is a problem that is here to stay. The best way to prevent WNV is to protect yourself from mosquito bites.
Mosquitoes often get WNV from birds. Dead bird reports are one way of tracking where WNV could be spreading. You can help the California Department of Public Health (CDPH) track WNV in California by reporting dead birds.
Report a Dead Bird Lookup Local Vector Agency
2021 West Nile Virus Activity in California
Last Updated: Jul 30, 2021 4:17pm PST
4
Human Cases
94
Dead Birds
563
Mosquito Samples
10
Sentinel Chickens
1
Horses
Did you know?
West Nile virus is the most common and serious vector-borne disease in California. There have been more than 7,000 human cases and over 300 deaths reported in California since 2003. The mosquitoes that spread WNV are found throughout the state.
Weekly Updates
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Human Cases Year-to-date: 4 Counties: 4
There was 1 new WNV positive human case reported in California last week from Shasta County. This is the first WNV positive human case from Shasta County this year.
1 WNV-related fatality has been reported to CDPH this year from 1 jurisdiction: San Luis Obispo (1).
4 human cases from 4 counties have tested positive for WNV in 2021. -
Dead Birds Year-to-date: 94 Counties: 9
There were 10 new WNV positive dead birds reported in California last week from the following counties: Los Angeles (4), and Sacramento (6).
94 dead birds from 9 counties have tested positive for WNV in 2021. -
Mosquito Samples Year-to-date: 563 Counties: 20
There were 149 new WNV positive mosquito samples reported in California last week from the following counties: Butte (10), Fresno (18), Kern (8), Kings (3), Lake (1), Los Angeles (11), Madera (9), Placer (12), Sacramento (1), San Bernardino (1), San Joaquin (33), Shasta (2), Stanislaus (6), Sutter (5), Tulare (26), Yolo (1), and Yuba (2). This is the first indication of WNV from Lake County this year.
563 mosquito samples from 20 counties have tested positive for WNV in 2021.A mosquito sample may contain up to 50 individual mosquitoes.
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Sentinel Chickens Year-to-date: 10 Counties: 3
There were 10 new WNV positive sentinel chickens reported in California last week from the following counties: Butte (8), Merced (1), and Shasta (1). These are the first WNV positive sentinel chickens from Butte, Merced, and Shasta counties this year.
10 sentinel chickens from 3 counties have tested positive for WNV in 2021. -
Horses Year-to-date: 1 Counties: 1
1 horse from 1 county has tested positive for WNV in 2021.
WNV Prevention and Information
Protect yourself and your community from WNV:
- Dump and drain standing water around your home
(check pet dishes, flower pots, and kiddie pools) - Use insect repellent when going outdoors
(especially at dawn and dusk)
Don’t Give Bugs a Biting Chance!
Insect Repellent Toolkit
WNV Prevention Resources
Found a dead bird? Report it online or give us a call at 1-877-WNV-BIRD
If you find a dead bird (especially a crow, jay, magpie, raven, sparrow, finch, or hawk) please file a report online or call toll-free 1-877-968-2473 (1-877-WNV-BIRD). Dead bird reports are often the first sign that WNV is active in an area, and they help CDPH track WNV in California all year long.