The US Centers for Disease Control and Prevention reported Monday that West Nile virus cases were continuing to climb across multiple states as peak mosquito-transmission season deepened through August. The agency renewed guidance urging residents to use repellent and remove standing water.

West Nile remains the leading cause of mosquito-borne disease in the continental United States. The CDC's ArboNET surveillance system tracks reported infections by state, with most cases historically concentrated in California, Texas, Arizona and the upper Midwest during late summer.

State and county health departments have reported both non-neuroinvasive and more severe neuroinvasive cases in recent weeks, alongside positive mosquito pools and infected birds. Public health laboratories in Texas and Arizona confirmed additional detections, and several counties issued spraying advisories.

The CDC noted that roughly one in five infected people develop fever and other symptoms, while about one in 150 develop serious neurological illness such as encephalitis or meningitis. Older adults and people with weakened immune systems face the highest risk of severe disease.

A CDC spokesperson said prevention remained the most effective defense, given the absence of a human vaccine or specific antiviral treatment. The agency recommended EPA-registered repellents, long sleeves at dawn and dusk, and repairing window screens.