Overview
- Public health data show an early August rise in West Nile activity with Maricopa County reporting 54 of Arizona’s 71 infections and five deaths.
- San Diego County has recorded a fourth human case since June, including one locally acquired infection, and has seen more West Nile–positive dead birds and mosquito samples than in 2025.
- California reported its second West Nile death of 2026 in Glenn County and statewide testing has found hundreds of infected birds and mosquito pools.
- Local agencies are expanding mosquito trapping and testing and using targeted abatement while urging residents to remove standing water, use EPA-approved repellent, wear long clothing, and repair screens.
- Most infections are mild or symptomless but older adults and immunocompromised people face higher risk of severe neurological disease, and experts warn human cases often peak in late August to early September so vigilance should continue.