It’s been nearly a month since Missouri issued a health alert over an increase in reported Shiga toxin-producing Escherichia coli (STEC) illnesses in the St. Louis area, and the one positive development is that none of those infected will be spending Thanksgiving in the hospital.

Four more cases of E. coli O157:H7 matching the outbreak strain have been confirmed in the past 10 days, so the number of people sickened has risen to 36, according to the Missouri Department of Health and Senior Services (DHSS).  About two-thirds of the ill people required some hospital treatment. 

“We are not aware of any cases still being hospitalized,” Jacqueline Lapine at DHSS told Food Safety News.  With the number of infections appearing to level out at 36, Lapine said sixty-one percent of those who became ill in St. Louis were female. They ranged from one to 94 years old.

Two residents of Columbia, MO, located halfway across the state west of St. Louis, are included as “confirmed cases” in the St. Louis outbreak. Two other recent cases of E. coli O157:H7 in Columbia are not included in the 36.

“Officials cannot, at this point, say conclusively that there is ‘a connection’ or ‘no connection’ between the St. Louis area outbreak and the Boone County (Columbia) cluster,” the Columbia/Boone County Department of Health says. “While it cannot be linked to common source at this time, investigators continue to explore all possibilities.”

What caused the outbreak remains a mystery.  

Early on, it looked like Missouri was going to trace the cause of the St. Louis E. coli outbreak in short order. Most, but not all, of those who became ill reported eating at one of the popular salad bars operated by the St. Louis-based Schnucks grocery store chain.

With 66 stores, Schnucks is the dominant salad bar operator in the St. Louis metropolitan area. In the first week after announcing the outbreak, Missouri officials were collecting food samples from the Schnucks salad bars and eventually tested 55 separate food items.

All were negative for E. coli.    

Schnucks on Oct. 31 said it was changing out all the products sampled anyway, just to be sure, while noting that nothing had come back positive for E. coli and no original source for the E. coli contamination had been pinpointed.

That remains true today. Saturday will mark one month since officials went public with the outbreak.    

That leaves the investigation in a tough spot. It generally becomes harder to find the origin of an outbreak once it is over. Missouri officials, with help from the federal Centers for Disease Control and Prevention (CDC) and U.S. Food and Drug Administration (FDA), say they are “moving further up the food distribution chain.”