Overview

• CDC data show roughly 770 U.S. cases as of early September, about 40% above average for this point in the season, with many classified as severe.
• Los Angeles County confirmed its first human cases of 2025, with four residents hospitalized between late July and late August from the Antelope Valley, San Fernando Valley and central Los Angeles.
• Illinois reported its first West Nile–related death of the year, a suburban Cook County resident in their 60s, as the county logged 33 cases since May with 22 neuroinvasive.
• Wayne County, Michigan, reported its first West Nile death of 2025 involving an older adult with underlying conditions, with state officials citing 17 human cases and a separate West Michigan death in August.
• Local indicators and responses continue to mount, including Kalamazoo County’s first human case, a Worcester, Massachusetts case prompting targeted spraying, and a Seneca County, New York horse euthanized after testing positive.