Ten cases of Salmonella Typhimurium have been reported in Kane County in northeastern Illinois over the past two weeks and officials with the county, state and local health agencies are investigating whether a restaurant may be connected to the outbreak.

Seven of the case patients reported having eaten at Portillo’s in St. Charles in April, the Kane County Health Department reported in a news release.  No specific food item has been identified as the source of the outbreak.

“The management of Portillo’s is actively cooperating with state and local health officials in the investigation,” said the statement. “The restaurant was sanitized over night Monday, and is having all its food handlers tested for possible infection.”

Before returning to work the food handlers will have to provide the results of two negative lab tests, the health department said. The restaurant has called in workers from its other locations so that it can operate while waiting for the test results. 

The 10 case patients have matching Pulsed-Field Gel Electrophoresis (PFGE) — the same genetic pattern of the Salmonella ser. Typhimurium, a pattern that is rare in Illinois. At least two additional cases of S. Typhimurium are pending the PFGE results. Cases in other states have also been identified.