Louisville Issues West Nile Virus Alert

The Louisville Metro Department of Public Health and Wellness (LMPHW) is alerting the Kentucky community to a concerning increase in West Nile virus (WNV) infections in Jefferson County, home to over 780,000 residents.

As of early October 2025, nine residents have been confirmed to have contracted the virus, with seven requiring hospitalization.

All individuals affected have been adults between the ages of 40 and 70. No deaths have been reported in Jefferson County, located in the western portion of Kentucky, related to WNV in 2025.

West Nile virus activity typically occurs during the summer months and into the early fall in Kentucky. This year's spike in WNV contrasts with 1 case in 2024 and 7 in 2023, as reported by LMPHW.

Dr. Kris Bryant, pediatric infectious disease specialist and associate medical director for LMPHW, noted in a press release that in most instances, people infected with WNV either show no symptoms or relatively mild symptoms. 

Less than 1% of infected people develop a serious neurologic illness such as encephalitis or meningitis.

"Serious illness can occur in people of any age," Dr. Bryant added.

According to the U.S. CDC, there were 1,324 WNV cases nationwide as of September 2025. The states of Colorado (241) and Texas (51) were among the leaders.

In Texas, Dallas County Health and Human Services recently reported 8 human cases and the first WNV-related fatality for the 2025 season.

From a prevention perspective, avoiding mosquito bites is best, as there are no WNV vaccines available this year.