22-07-2025
First mosquitoes carrying West Nile virus found in Orange County
Culex mosquitoes bite at dawn and dusk and tend to feed off birds, common carriers of West Nile virus.
The first mosquitoes carrying West Nile virus this year were detected in Orange County, the Orange County Mosquito and Vector Control District reported Tuesday.
The agency confirmed that the mosquitoes were collected in Anaheim and Garden Grove and tested positive for the virus — the first samples to test positive in the county during this year's monitoring. A dead bird recovered in Garden Grove has also tested positive for the virus.
The positive mosquitoes were collected near Euclid Avenue, West Broadway, Interstate 5, and West Ball Road in Anaheim; Magnolia Street, West Cerritos Avenue, Gilbert Street and West Katella Road in Anaheim; Haster Street, Lampson Avenue, Lewis Street, and State Route 22 in Garden Grove; and Gilbert Street, Lampson Avenue, Brookhurst Street and Garden Grove Boulevard in Garden Grove.
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Orange County as of Tuesday has no reported human cases of West Nile virus.
West Nile virus is transmitted to people primarily through infected mosquito bites. Mosquitoes acquire the virus when feeding on infected birds.
'Multiple mosquito samples and a dead bird testing positive for West Nile virus indicate that the virus is circulating in the community,' said Amber Semrow, OCMVCD's director of Scientific and Technical Services. 'Anaheim and Garden Grove are historically high-risk areas for West Nile virus activity. Conditions across the region are favorable for sustained virus activity during the warm summer months.'
OCMVCD plans to continue surveillance, inspections and control measures for mosquitoes in the county to prevent more mosquito breeding. The agency will also post an advisory sign to alert residents in the area.
'Everyone in Orange County should do their part to prevent mosquitoes,' said Brian Brannon, OCMVCD spokesperson. 'Dumping and draining standing water is the most effective and environmentally-friendly way to rid mosquitoes from our communities.'
O.C. residents are urged to prevent mosquito bites by dumping an draining containers holding water at least once a week; cleaning and scrubbing bird baths or pet water bowls; wearing repellent with DEET, picaridin, IR3535, or oil of lemon eucalyptus. Closing unscreened doors and windows can also prevent mosquitoes from entering a residence. Light-colored, loose-fit clothing during dusk and dawn are also encouraged.
Visit for more information about mosquito prevention.
