Overview
- Health officials report an unusually early and broad increase in West Nile virus activity across multiple U.S. counties and in Israel, driven by more infected mosquito pools and dead bird detections.
- Maricopa County, Arizona, has emerged as the U.S. hotspot with the largest caseload reported so far and multiple deaths, while California has recorded at least two statewide fatalities this season.
- Several jurisdictions announced their first human cases of 2026 in early August, including Orange County, San Diego County, Iowa and Gaston County in North Carolina, with other states and suburbs detecting positive mosquito batches.
- Authorities are expanding actions that include more mosquito trapping and pooled testing, targeted larvicide and adulticide operations, blood-donation screening and public advisories urging source reduction and use of EPA-registered repellents.
- Vector-control work faces practical limits such as insecticide resistance and high mosquito activity, so officials stress early larval targeting, community removal of standing water, repair of screens and protecting older or immunocompromised people from bites.