Dead Crow Positive for WNV Collected in Foster City

UPDATE: Feb. 7th, 2018

Follow-up mosquito trapping in the area where the bird was found did NOT detect any mosquitoes infected with WNV.

On Feb. 5th, a dead American crow collected in Foster City tested positive for West Nile virus. This is the first sign of the virus in San Mateo County in 2018.

Since birds sometimes fly long distances, it’s possible that the crow was infected outside San Mateo County. To check for risk of local transmission, the laboratory staff will set mosquito traps in the area where the crow was found. If infected mosquitoes are found, we’ll know that there’s a risk that the virus could be passed on to people in the area. If no infected mosquitoes are found, it’s likely that there’s not an elevated risk of WNV in the area -  but we’ll keep watching for other signs of WNV, just in case.

You can help out by keeping an eye out for dead birds, and reporting any you find to the District. If you find one, give us a call at (650) 344-8592. Carcasses that are in good condition and appear to have been dead less than 24 hours can be tested for WNV.

You can also reduce the risk of WNV in your neighborhood by preventing mosquitoes. Check your property regularly for standing water where mosquito larvae may be developing, and overturn or get rid of any items that will fill with water when it rains. If you have something you can’t dump out, like a pond, give us a call. We can provide water treatments, mosquito-eating fish, or advice on other solutions. There’s no charge for a technician visit or any of our other services.

If mosquitoes are already a problem in your area, let us know. We can help locate the source, even if it’s not on your property. You can make a service request online or by calling the office at (650) 344-8592.

Other questions about WNV? Check out our FAQ.