The person who was diagnosed is in their 60s and was hospitalized, but is now recovering at home, officials said.
Health officials warned residents to be mindful of mosquitos potentially carrying the virus.
No mosquitoes in Long Beach have been found to be positive for the virus thus far this season.
Health officials first discovered mosquitoes with West Nile Virus in Long Beach in mid-July.
So far this year, 10 human cases of West Nile have been reported in California, two of which were identified by the Los Angeles County Department of Public Health.
According to the county Department of Public Health, the patients are a resident of the San Fernando Valley and a resident in the “southeastern region” of the county.
The news comes two weeks after the virus was found in the Long Beach area—the season’s first detection of the virus.
The mosquito sample was the first to test positive for West Nile virus in Los Angeles County so far this year, authorities said.
The case was found in Central Long Beach, north of Spring Street, according to Environmental Health Bureau Manager Nelson Kerr.
An elderly man has become the first confirmed person to die from the West Nile Virus in Long Beach this year, city health officials announced Wednesday.