MONROE — Green County Public Health (GCPH), in coordination with the Wisconsin Department of Health Services (DHS), is sharing a public health update following a recent detection of measles virus in untreated wastewater collected from the city of Monroe on October 28, 2026. This is the third wastewater detection of measles in untreated wastewater in Green County this year, with previous positive test results on September 16, and October 14. Health officials confirm that there are currently no confirmed cases of measles in Green County, and these wastewater findings have not been linked to any known cases or travel.

Wastewater monitoring is an ongoing, routine tool used across Wisconsin to monitor health trends in communities. When measles is detected in wastewater from a community, it means that one or more people infected with measles were present in the community around the time the sample was collected. Wastewater can represent both the city and the surrounding areas, as well as people who may travel in and out of the area for activities such as work, school, or health care. Someone who does not live in a community could therefore be represented in wastewater while they are there. Public health officials emphasize that there are currently no confirmed cases or public exposure locations in Green County.

Green County Public Health is working closely with DHS to further investigate the wastewater detection and possible sources. “We are sharing this update to help keep our community informed, and to encourage residents to make sure they are up to date on routine vaccinations,” says RoAnn Warden, Public Health Officer.

Wastewater testing alone does not tell us who is sick, but it can serve as a surveillance tool to detect measles in the area. This is why it is important for people to ensure that they and their family are vaccinated against measles, are aware of the symptoms of measles, and can talk to their doctor if they are concerned about measles.

Measles is a viral illness that typically begins with a high fever, cough, runny nose, and red, watery eyes. Within a few days, a rash will appear, beginning as flat red spots on the face, usually at the hairline, and spreads downward to the neck, trunk, arms, legs, and feet.

Measles is spread from person to person, often through the air on droplets of saliva. This may look like a sick person coughing or sneezing. The measles virus can stay in the air for up to two hours after a sick person has been in a room and may cause infection in up to 90% of unvaccinated people who are exposed to the virus.

Individuals who have measles can spread the virus to others four days before through four days after the rash appears. If you suspect that you have symptoms of measles, such as a fever, cough, or rash, especially after contact with someone who has measles, please contact a health care provider. If you suspect you have measles, call the healthcare facility before seeking medical attention to avoid spreading the disease.

Measles can be prevented with the measles, mumps, and rubella vaccine (MMR). Two doses of the vaccine are about 97% effective at preventing the disease. In general, people born before 1957 are considered immune and do not need a vaccine. All other adults without laboratory evidence of immunity should have at least one dose of measles-containing vaccine, and children should have two doses. For more information on who should get a measles vaccine, visit the DHS measles webpage.

If you do not know if you or your children have been vaccinated to protect against measles, check the Wisconsin Immunization Registry or contact your health care provider or local health department.

Anyone who may not be vaccinated to protect against measles can still get vaccinated. Your regular health care provider, local clinic or pharmacy, or local health department can help you determine what vaccines you need to protect your health. Vaccines are available at local clinics and pharmacies. Uninsured residents can call Green County Public Health at 608-328-9390 to learn about free MMR vaccines available through public health programs. See the DHS measles webpage for more information on measles vaccines.