U.S. health departments report first West Nile virus cases in mosquitoes, advise precautions.

In 2025, multiple areas across the U.S., including Texas and Illinois, have reported the first cases of West Nile virus in mosquitoes. No human cases have been reported in most areas, except for Williamson County, Texas, where a 40-year-old resident was diagnosed with West Nile neuroinvasive disease. Health departments advise residents to use repellent, wear protective clothing, and eliminate standing water to prevent mosquito bites and reduce mosquito populations. Most people infected with West Nile virus show no symptoms, but severe cases can lead to brain inflammation.