Los Angeles County public-health officials are warning residents to take mosquito precautions after confirming the county’s first human case of West Nile virus for the 2026 season.

The patient lives in the Antelope Valley and was hospitalized after developing West Nile encephalitis following the onset of symptoms in late June. The case was announced July 13. Although it was not reported in Torrance, county health officials emphasize that the mosquito species capable of transmitting West Nile virus is found throughout Los Angeles County.

West Nile virus is transmitted through the bite of an infected mosquito. Mosquitoes become infected after feeding on birds carrying the virus and can then pass it to people and other animals.

Most infected people experience no noticeable illness. Others may develop fever, headache, nausea, body aches, fatigue, or a skin rash. In uncommon but serious cases, the virus can affect the nervous system and cause meningitis, encephalitis, paralysis, or death.

Adults over age 50 and people with chronic health conditions face a greater risk of severe illness. Approximately one in 10 patients who develops severe neurological disease dies from related complications, according to Los Angeles County Public Health.

There is no vaccine for people and no specific treatment that eliminates the infection. Prevention therefore depends primarily on avoiding bites and reducing mosquito-breeding locations.

Health officials recommend that Torrance residents take several immediate steps:

• Empty and scrub containers that collect water at least once each week.
• Check buckets, flowerpot saucers, toys, pet bowls, gutters, tarps, and rain barrels.
• Keep swimming pools clean and properly chlorinated.
• Remove water collecting on pool covers.
• Repair damaged window and door screens.
• Use an EPA-registered insect repellent when outdoors.
• Consider long sleeves and long pants when mosquitoes are active.
• Take extra precautions around dawn and dusk.
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Even a small amount of standing water can become a breeding site. Mosquitoes may lay eggs in containers that seem too shallow or insignificant to create a problem.

Residents should also watch for neglected or green swimming pools, which can produce large mosquito populations. Suspected breeding problems can be reported to the appropriate local vector-control agency.

Dead birds can provide an early indication that West Nile virus is circulating in a community. California accepts dead-bird reports through its West Nile virus surveillance program at (877) 968-2473.

A person who develops severe headache, high fever, neck stiffness, confusion, muscle weakness, tremors, or other significant neurological symptoms should seek medical attention promptly.

The county’s first confirmed case does not mean a Torrance outbreak is underway. It does mean mosquito season is active and that residents should address standing water before mosquitoes have an opportunity to multiply.

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