Wisconsin health officials confirmed two laboratory-tested measles cases in Vernon County on Wednesday, adding a new investigation to a growing series of infections around the state. The Wisconsin Department of Health Services said September 16 that the State Laboratory of Hygiene confirmed both cases and that investigators are determining whether they are connected to previously reported measles activity.
No public exposure locations had been identified when the department issued its announcement. State and county public-health teams are identifying and notifying people who may have been exposed; if investigators find a location where the public may have encountered the virus, DHS said it will add that information to its outbreaks and investigations page. The agency did not release personal details about the patients.
The Vernon County announcement followed a separate confirmation one day earlier. In that case, DHS said a Marathon County resident was exposed during out-of-state travel and that the infection was not connected to the ongoing outbreak in southwestern Wisconsin. Officials likewise had not identified any public exposure locations for that case at the time of the September 15 release.
The new investigations come after a significant regional outbreak. On August 18, DHS reported that the southwestern Wisconsin outbreak had reached 36 confirmed and three probable cases. That update linked two Grant County infections to cases in Iowa and Lafayette counties. The latest Vernon County cases have not yet been publicly tied to that cluster, so the state’s investigation remains important to understanding whether transmission is continuing across the region or reflects a separate chain.
For residents, the immediate advice is practical. Measles spreads through the air and can remain airborne for up to two hours after an infected person coughs or sneezes. Symptoms usually begin 10 to 21 days after exposure and can include a runny nose, high fever, fatigue, cough, red watery eyes and a raised red rash that begins at the hairline before moving down the body. Anyone who develops symptoms should stay home and call a clinic before arriving so staff can limit exposure to other patients.
Vaccination coverage is a central concern as students return to classrooms. A September 3 DHS update put the statewide measles, mumps and rubella vaccination rate among kindergarteners at 85.1% for the 2025-26 school year, up slightly from 84.8% a year earlier but well below the 95% level generally needed to prevent community spread. Nonmedical exemptions increased from 6.3% to 7.3% over the same period.
DHS says two doses of the MMR vaccine are 97% effective at preventing measles. Families can review records through the Wisconsin Immunization Registry or contact a health care provider. The department’s current notices do not call for broad closures or travel restrictions; they instead emphasize monitoring for symptoms, confirming vaccination status and waiting for investigators to publish any verified exposure sites.
