Health officials warn of West Nile virus in mosquito in Alhambra, human infection in Long Beach

July 1, 2026 - 01:23

Public health authorities have issued a warning after detecting West Nile virus in mosquitoes collected in Alhambra, while also confirming the first human infection of the season in Long Beach. The twin developments this month signal an elevated risk for residents across the Los Angeles area.

The mosquito samples testing positive for the virus were trapped during routine surveillance in Alhambra, a city in the San Gabriel Valley. Officials have since stepped up spraying and larvicide treatments in the area to reduce the adult mosquito population and prevent further spread.

Separately, the Long Beach health department reported that a local resident has been infected with West Nile virus, marking the first human case in that city this year. The patient is recovering at home, and no additional details about their identity or specific exposure location have been released.

West Nile virus is transmitted through the bite of an infected mosquito. Most people who contract the virus experience no symptoms, but about one in five develop fever, headache, body aches, or a rash. In rare cases, severe illness can affect the nervous system, leading to encephalitis or meningitis. Older adults and those with weakened immune systems face the highest risk.

Health officials urge residents to eliminate standing water around homes, use EPA-approved insect repellent, and wear long sleeves and pants during dawn and dusk when mosquitoes are most active. They also advise ensuring window and door screens are intact to keep mosquitoes out.