First 2 Detections Of West Nile Virus During Mosquito Season Confirmed In Riverside County: Officials

NUEVO, CA — Riverside County has recorded its first two detections of West Nile Virus during this year's mosquito season, prompting officials to authorize an anti-mosquito spraying operation next week.

On Thursday, the Riverside County Vector Control Program confirmed two positive detections of West Nile Virus. The first positive mosquito pool was identified during routine surveillance in Nuevo. The second detection was confirmed through laboratory testing of a dead bird found near Spencer's Park in the unincorporated area of Murrieta.

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One case of human West Nile Virus infection has been documented in Riverside County so far this year.

Three people in California have died this year — all occurring this month. To date, there have been 30 West Nile Virus infections recorded in 2026, according to the California Department of Public Health.

In 2025, one person in Riverside County was infected with West Nile Virus. That patient recovered.

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Riverside County vector control officials said a mosquito treatment operation will be conducted in Nuevo to counter infestations that pose a potential health risk to the public.

The Department of Environmental Health also said because the West Nile Virus detection near Murrieta was not linked to any mosquito infestations, there are no plans to perform mosquito treatment in the area yet.

The Department of Environmental Health has scheduled insecticide spraying in Nuevo for Tuesday, Aug. 25, from 4:30 a.m. and 7 a.m. in three locations:

• Mystic Field, bounded by Lakeview Avenue to the south, Reservoir Avenue to the north, Orange Street to the east and Magnolia Avenue to the west;
• West Nuevo, bordered by Ninth Street to the north, 10th Street to the south, Reservoir to the west and Yucca Avenue to the east;

• East Nuevo, bounded by Reservoir to the north, Lakeview to the south, Fifth Street to the east and Sixth Street to the west.

County officials said notification signs will be posted along treatment routes beginning Friday.

RELATED: West Nile Virus Activity Prompts Mosquito Control Operation In Riverside County Starting Aug.20

Anti-mosquito spraying involves the use of chemicals approved by the U.S. Environmental Protection Agency. Pesticides are emitted as a mist dispersed from machines anchored in the backs of pickup trucks. Officials recommended that during operations, residents stay indoors and keep windows closed until at least 15 minutes after the trucks have departed.

Mosquitoes typically become carriers of the virus after feeding on an infected bird and can then spread the potentially lethal strain to animals and humans. Those at greatest risk include seniors and individuals with compromised immune systems.

Symptoms may never materialize, but can include fever, headache, nausea, body aches, skin rashes and swollen lymph nodes.

Mosquito season in Southern California generally spans May to October. To reduce exposure to mosquitoes with West Nile Virus, residents were advised to:

• Spend as little time as possible outdoors at dawn or dusk, when mosquitoes are generally on the move;

• Wear long pants and long-sleeved shirts during outdoor activity in mosquito-prone areas;

• Use insect repellent;

• Ensure door and window screens are fitted properly to keep bugs out; and

• Get rid of standing water, aside from pools properly treated with chemicals.

Anyone with concerns should contact the Department of Environmental Health at 951-766-9454.

Additional information is available at rivcoeh.org/vector-control.

City News Service contributed to this report.