The Contra Costa Mosquito and Vector Control District announced on Friday that they found a second bird that tested positive for West Nile virus, according to a report by Bay City News.

The bird was an American crow from Walnut Creek. Birds are one of the main carriers for the virus. The virus is transferred to birds through the bite of an infected mosquito. The virus can then be transmitted to humans through bites from infected animals.

Some serious symptoms of a West Nile virus infection include fever, severe headaches, stiff neck, disorientation or confusion.

Contra Costa County residents are advised to report dead birds by phone at (877) WNV-BIRD (968-2473). Mosquito service for residential properties in Contra Costa County can also be requested by calling (925) 685-9301.