Dead Bird Surveillance
Did you know that dead birds can indicate local West Nile virus activity?
Birds become infected with West Nile virus when they are bitten by a mosquito carrying the virus. Mosquitoes that bite birds infected with West Nile virus become infected and can pass the infection to humans, birds, and other animals. Birds from the Corvidae family, like crows, ravens, and jays, are susceptible to West Nile virus and may die. Other birds, like chickens, may be infected but do not become sick or die from West Nile virus.
Please help us by reporting dead birds online at https://westnile.ca.gov/report.php or by calling 1-877-WNV-BIRD
2021 West Nile virus data
As of August 5, 2021, there have been 205 dead birds reported in San Mateo County. Of those, 61 have been suitable for testing and all have tested negative for West Nile virus (WNV). To date, there have been no West Nile virus detections in mosquitoes or sentinel chickens in San Mateo County in 2021.
Statewide, there have been 8 human cases of WNV in 2021 compared to a five-year average of 8.4 cases at this date. Throughout California, 3,538 dead birds have been reported and 1,069 have been tested with 109 (10%) dead birds positive for WNV. Additionally, 770 mosquito samples have tested positive for WNV compared to a five-year average of 1,166 at this date. Ten sentinel chickens have tested positive, which is also below the five year average of 30.6.