The U.S. Centers for Disease Control and Prevention said Thursday that an outbreak of E. coli bacteria in four Midwestern states from an unknown source affected another 47 people, bringing the total to 84.
As of Wednesday, 38 people have been hospitalized. Although many strains of E. coli bacteria are found in the intestines of healthy people and animals and are harmless, certain types can cause severe intestinal cramps, bloody diarrhea and vomiting.
The CDC said that of the 62 people it interviewed, 52 had eaten at Wendy’s in the week before their illness began.
“We are fully cooperating with public health authorities in their ongoing investigations into the outbreak of E. coli at the local level,” the burger chain said.
The new cases represented an increase from last Friday, when the US centers began an investigation following 37 people were infected across Michigan, Ohio, Indiana and Pennsylvania.
The centers said that many of them had eaten sandwiches with romaine lettuce at Wendy’s before they fell ill.
However, the CDC has not advised once morest eating at Wendy’s or asked people to avoid romaine lettuce as it is not yet certain the exact cause of the outbreak.
As a precaution, the company that owns the restaurant chain confirmed the replacement of lettuce in sandwiches in some affected areas.
And the American centers said that the real number of patients is likely to be higher than the recorded, and the outbreak may not be limited to the states where cases have appeared.