WGN Local News in Lombard, Illinois reported Thursday that a Subway restaurant has been closed by the DuPage County Health Department after several customers contracted Shigellosis, a gastrointestinal illness.

The Health Department said 8 confirmed cases had been reported, and of those 8 victims, 4 were hospitalized. As many as 50 more cases of illness are possible, according to officials, and the agency is advising that anyone who ate at the Subway located at 1009 E. Roosevelt Road between February 24 and March 4 to contact the Health Department. 

Shigellosis, a bacterial illness caused by the ingestion of Shigella bacteria, can cause diarrhea, which is often bloody, vomiting, fever, and stomach cramps one to two days after being exposed to it. Although the illness usually resolves in 5 to 7 days, the young and the elderly are more vulnerable to extended sickness and more severe symptoms.

The Subway in Lombard is an oft-visited spot for hungry high school students from nearby Montini Catholic High School, and as a result, 4 students and 3 teachers have acquired the illness. One of the students was taken to the emergency room.

The illness is especially dangerous for people like students and teachers who spend their time in a crowded environment, as the illness can pass from one infected person to the next. It can also be acquired from contaminated food, and those infected can remain contagious for up to 4 weeks.    

The Department of Health is not sure where the Subway outbreak began, but officials said it could have come from the food or someone in the restaurant.

The restaurant has been closed pending further investigation, according to a statement from the Health Department, which said the restaurant’s owners and corporate representatives are cooperating with investigators.

According to the Health Department, the infection can be stopped with careful and thorough hand washing, particularly after using the restroom.