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Vector control officials confirm first positive mosquito samples of 2026 as mosquito season ramps up across Los Angeles County.
May 20, 2026
By Brian Hews
The first West Nile virus activity of 2026 has been detected in Los Angeles County after mosquito samples collected in Pico Rivera and Long Beach tested positive for the virus, according to the Greater Los Angeles County Vector Control District.
The agency announced Wednesday that mosquito traps in both cities confirmed the presence of West Nile virus in local mosquito populations, marking the first positive mosquito samples detected this year.
Officials warned the early detections are a sign mosquito season is already underway across Southern California.
“West Nile virus is regularly detected in the environment throughout Los Angeles County, and these early detections are a reminder that mosquito season is already underway,” GLACVCD Scientific-Technical Manager Angela Caranci said in a statement.
The virus is primarily spread through bites from infected Culex mosquitoes, which are most active during dusk and dawn hours.
Health officials urged residents to begin taking precautions immediately, including removing standing water around homes and using mosquito repellent outdoors.
“Dumping standing water, reporting neglected swimming pools, and using mosquito repellent are simple but effective ways to reduce risk,” Caranci said.
There is currently no human vaccine for West Nile virus.
According to the Centers for Disease Control and Prevention, repellents containing DEET, Picaridin, IR3535, or Oil of Lemon Eucalyptus are considered safe and effective when used as directed.
Vector control officials stressed that neighborhood mosquito prevention depends heavily on residents maintaining their own properties.
“The District’s mosquito control efforts are most effective when paired with community action,” Caranci added. “Residents play a vital role in reducing mosquito breeding by routinely inspecting their properties and eliminating standing water.”
Officials advised residents to:
Eliminate standing water from gutters, buckets, tires, rain barrels, and other containers.
Maintain pools, spas, and ornamental ponds.
Change water in pet dishes and bird baths weekly.
Report neglected or green swimming pools to vector control authorities.
Report dead birds to the California Department of Public Health.
West Nile virus can cause fever, headaches, body aches, nausea, and rashes. In severe cases, the illness can lead to hospitalization, paralysis, coma, or death. Health officials estimate about one in 150 infected individuals develop severe symptoms requiring hospitalization.
The Greater Los Angeles County Vector Control District serves communities throughout Los Angeles County from its headquarters in Santa Fe Springs.
For more information, residents can visit www.GLAmosquito.org
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