The patients are residents of the San Fernando Valley and the southeastern region of L.A. County, according to the public health department.
West Nile is spread by the bite of an infected mosquito, and symptoms may include fever, headache, nausea, body aches and a mild skin rash, health officials say. The virus can affect the nervous system and result in meningitis, encephalitis, paralysis and even death.
People over the age of 50 and those with chronic health problems are at higher risk of severe illness.
While not all mosquitoes carry the virus, the type of mosquito that spreads West Nile is found throughout L.A. County.
Confirmed cases in L.A. County do not include Long Beach and Pasadena, as cases identified in those cities are reported by their local health departments.
More information can be found at publichealth.lacounty.gov/media/westnile