A dead crow found in Petaluma last week was infected with West Nile virus, the first confirmed case of the virus this year in Sonoma and Marin counties.

The American crow was discovered near Magnolia Avenue and Keokuk Street in Petaluma and was submitted for testing July 11.

"It's no surprise to find a dead bird that is positive for West Nile virus," said Nizza Sequeira, Public Relations Director of the Marin/Sonoma Mosquito and Vector Control District.

West Nile virus is spread by the bite of infected mosquitoes, which get infected from birds. Only 1 out of 150 people infected with the virus becomes seriously ill.

The mild weather has helped keep mosquito populations in check, but that could change quickly if summer temperatures rise, the district said.

Residents are reminded to eliminate sources of standing water, cover septic tanks, secure screens to windows and vent pipes, and wear long clothing and insect repellent while outdoors.

-- Kevin McCallum