The victim is a Santa Barbara County man who was recovering at home Saturday following a stay in the hospital, the Los Angeles Times said.
"We are intensifying our surveillance for the virus with the help of all counties," said Kathleen Billingsley, the department's chief deputy director.
Billingsley reminded Californians to avoid being bitten by mosquitoes as best they can. The virus is spread among people and animals by the pesky insects.
The Times said an infected crow found dead in the spring triggered the official start of West Nile season in the LA area back in May.
Health officials said the risk of becoming seriously ill from West Nile was low with only about 1 percent of humans who contract the disease developing meningitis or encephalitis. But people over 50 who have health issues such as diabetes or high blood pressure are at a higher risk of developing serious symptoms.