Seven cases of E. coli infections are being investigated by the Manitowoc County Health Department.

The department is waiting for test results from a state lab to determine the source of the infections, said Amy Wergin to the Manitowoc Herald Times-Reporter. Wergin is the county public health nurse manager.

"We are interviewing people and asking them where they have been and what they gave been in contact with to find similarities," she said. "If there is a common cause we may be able to abate that hazard."

"We’re concerned because this is a much higher rate of infection than normal and there might have been a common cause for infections," Wergin said.

The cases were referred to the health department from the patient’s health care providers.