A Mendocino Coast woman is the first person to be diagnosed with West Nile virus on the North Coast this year.
She also is the first person known to have contracted the mosquito-borne disease within Mendocino County, said Jennifer Dutton, communicable disease program manager for the Mendocino County Health and Human Services Agency.
"This is our first resident who has had no known travel outside the county," she said.
The two other Mendocino County residents who have been diagnosed with West Nile virus, both in 2007, are believed to have been bitten by mosquitoes infected with the virus while they were elsewhere, she said.
The woman, diagnosed in August, did not suffer serious problems as a result of the disease, Dutton said. An estimated 80 percent of people who are infected are unaware of it because their symptoms are mild or nonexistent, she said.
The woman was diagnosed after her doctor ran a test, Dutton said. She would not give additional information about the woman or what made her doctor test for the virus, citing privacy concerns.
Neither Sonoma County nor Lake County has reported a human case of West Nile virus this year.
Lake County has reported a horse and a bird with the virus, and Sonoma County has reported four birds.
Mosquito traps in both counties have found insects that were infected with West Nile virus.
Mendocino County, which also has had several dead birds test positive for the virus, does not trap mosquitoes.