L.A. County Now Has More Than Twice California's 2025 West Nile Cases

Pasadena reported its first two probable cases of the year Thursday, as California's count hit 452 cases and 29 deaths.

Two Pasadena residents are the city's first human West Nile virus cases of the year. The tests that would confirm them aren't back yet.

The Pasadena Public Health Department announced the cases Thursday. It said both patients meet the clinical criteria and the early lab criteria for the virus. They come late in a season. As of Oct. 23, the state agency's West Nile tracker counted 251 human cases in Los Angeles County.

The state tracker put California's total at 452 cases, spread over 24 counties. Twenty-nine people had died by then. Pasadena's release sets that 452 against last year: at the same point in 2025, California had 67 cases. For all of 2025, the state counted 117 cases and 11 deaths, according to its 2003-2026 case summary.

The numbers were still going up. In the state's weekly bulletin for Oct. 23, California added 74 human cases, and 59 of them came from L.A. County.

The county health department keeps its own count, which leaves out Pasadena and Long Beach because those cities have their own health departments. In July, when the county announced its first case, a hospitalized Antelope Valley resident with brain inflammation, it said it had averaged 41 cases a year over the previous five years. By Sept. 21 the county was at 100 cases and five deaths, ABC7 reported. That was the most this early in nearly a decade, and almost every patient had severe illness of the brain or spinal cord and needed a hospital. "The number of severe cases and deaths we are seeing this year is concerning," county Health Officer Dr. Muntu Davis said, according to ABC7.

None of this is new territory. West Nile first showed up in California's human counts in 2003, with three cases. Two years later the state had 880. Since 2003 it has recorded more than 8,000 cases and more than 400 deaths. This year's count, 502 in the state's case summary, is the highest total since 2017, when the state had 556.

What makes this year stand out is how quiet the two before it were. A virus that never left came back in numbers L.A. hadn't seen in close to a decade.

Pasadena says it's working with the San Gabriel Valley Mosquito and Vector Control District on inspections and treatment in public spaces, and that its last confirmed case was in 2025. The city notes there's no vaccine or cure for the disease. Its advice: dump standing water once a week, get rid of containers you don't use, patch window screens, and wear repellent with DEET, picaridin, IR3535 or oil of lemon eucalyptus. Dead birds can carry the virus and help the state track it. They can be reported at 1-877-968-2473.

In L.A. County, the stretch when mosquitoes are worst lasts from June through November, ABC7 reported. Pasadena's first two cases landed with a month of it still to go.

Source: cityofpasadena.net, retrieved October 30, 2026. Other sources: the State of California's West Nile tracker, Los Angeles County, abc7.com.