The source of two cases of E. coli O157:H7 reported in Manitowoc County in March are under investigation, said Amy Wergin, public health nurse manager for the Manitowoc County Health Department.

“It doesn’t appear that the public is at risk,” she said.

The department is conducting the investigation with the Wisconsin Department of Health Services, she told htrnews.com.

“We have two cases of E. coli that have the same fingerprint. We are trying to discern what the link is between the two,” Wergin said. “Right now, these are the only two in the nation with this fingerprint.”

Four other cases in May of 2012 had the same strain — two in Manitowoc, one in Brown County and one in Colorado, Wergin said.

While the source of the E coli is yet unknown, if it was linked to a large fast-food restaurant chain, there likely would be more cases, she said.