MADISON, Wis. — Two new measles cases have been confirmed in counties bordering Green County, prompting Wisconsin health officials to warn that additional cases could be circulating in southwestern Wisconsin without yet being identified.

The Wisconsin Department of Health Services, along with the Iowa County and Lafayette County health departments, announced Tuesday that testing at the Wisconsin State Laboratory of Hygiene confirmed one case in an Iowa County resident and another in a Lafayette County resident. They are Wisconsin’s third and fourth confirmed measles cases of 2026.

The cases are particularly noteworthy for residents of New Glarus and Green County because Lafayette County borders Green County to the west and Iowa County borders it to the northwest. Unlike Wisconsin’s first two confirmed measles cases this year, which were associated with international travel, DHS said the two newest patients are believed to have been exposed within Wisconsin.

That raises the possibility that other people carrying measles have not yet been diagnosed. DHS said the circumstances suggest additional cases could exist in the community that public health officials have not identified. The Iowa and Lafayette county cases are not believed to be connected to Wisconsin’s earlier confirmed cases.