Measles has been detected in Louisville’s sewage, meaning at least one person was infected with the disease earlier this month, according to the Louisville Metro Department of Public Health and Wellness.
“While no measles cases have been reported to public health officials, this detection in wastewater means there was at least one person with an undiagnosed or unreported measles infection present in the area around the time of this detection,” wrote Associate Medical Director Dr. Kris Bryant with the city’s Department of Public Health.
Kentucky has four reported cases of measles thus far this year, but no one in Louisville has reported suffering from the highly contagious disease. Last year, there were 13 confirmed measles cases in the state, and all but one presented in Kentuckians who were unvaccinated or with unknown vaccination statuses.
The earliest measles symptoms are usually similar to other viral infections — cough, runny nose, fever — and later infected people usually develop a rash and severe fever. Young children, pregnant women and people with weak immune systems are the most at risk of severe complications including pneumonia and brain swelling.
Bryant wrote that two doses of the measles, mumps and rubella vaccine is the most effective method to defend against infection. In the letter, Bryant noted that international travelers, college students and those working in healthcare are the adults most at risk.
The country is still in the midst of a measles outbreak, with more than 2,200 measles cases reported across the U.S. this year — nearly matching the entirety of 2025 when 2,289 individuals were reported to have measles. It’s the highest case level the U.S. has seen since 1991, when more than 9,600 cases were reported, and just nine years before measles was declared eliminated in the country.
All four Kentucky cases reported this year occurred in central Jessamine County in January, and three of those infected were under five years old.
Bryant encouraged healthcare providers to be more suspicious of symptoms and consider a measles diagnosis for patients with a fever and rash. The virus was detected during routine untreated wastewater testing between July 6 and July 14.
