SAN DIEGO -- The first dead bird found in San Diego County to test positive for West Nile virus this year was discovered last month in Vista, health officials said Friday.

The sharp-shinned hawk was found Feb. 2, and the positive result was returned on Tuesday, according to the county Vector Control Department.

The exact location of the discovery was not released.

Last year, 19 infected birds were found around the county, along with three horses. Two humans were infected last year, but none so far in 2007.

According to the Centers for Disease Control, one in 150 humans who contract West Nile Virus will suffer severe symptoms. Most others will have high fever, headaches and neck stiffness.

County Department of Environmental Health Director Gary Erbeck said the key to preventing the spread of the virus is mosquito control.

Recent rains have given mosquitos breeding areas, so residents should remove any standing water on their property, Erbeck said.