Two birds from Napa County have tested positive for West Nile Virus, county health officials reported Friday.

The two American crows were found in the Carneros region on Sept. 18, according to information provided by Napa County and the Napa County Mosquito Abatement District. The test results came back positive for West Nile on Wednesday.

The birds are the first reported West Nile Virus cases in Napa County this year, Abatement District manager Wes Maffei said Friday.

There is no way to ascertain where the birds got the virus. Birds fly long distances and do not show symptoms right away, Maffei said.

West Nile Virus has been present in Napa County for the past three years.

The first human case was reported last September.

The 52-year-old man recovered fully and did not have to be hospitalized, according to a Napa County written statement.

Infected mosquitoes transmit the West Nile Virus. While most human cases seem to occur in August and September, West Nile cases can occur later, Maffei said.

According to the state Department of Public Health, most California counties have reported West Nile Virus activity.

In the meantime, officials urge residents to reduce their risk of getting the West Nile Virus by:

-- Avoiding staying outside at dusk and dawn, when mosquitoes are most active.

-- Wearing long pants and long-sleeved shirts outdoors.

-- Using mosquito repellent with DEET.

-- Repairing or replacing window mosquito screens that have tears or holes in them and draining pools of standing water.