West Nile virus cases surge early in US 2026, Arizona epicenter

The CDC reports that the 2026 West Nile virus season is the earliest and most severe since 2004, with 48 confirmed cases and 38 neuroinvasive infections recorded by June 30. Twenty‑three states have reported activity, the most in a decade, and Arizona accounts for 32 cases, overwhelmingly concentrated in Maricopa County, which has reported five deaths. Texas follows with four cases, while other states each have at least one confirmed infection.

Los Angeles County confirmed its first human West Nile case of the year, a resident of the Antelope Valley hospitalized with encephalitis. County health officials urged residents to use insect repellent, eliminate standing water, and secure screens, while local vector‑control agencies intensified mosquito‑control efforts.

Health experts stress that the virus spreads through common Culex mosquitoes breeding in urban standing water and that older adults and immunocompromised individuals are at highest risk of severe disease.