INDIANAPOLIS — The CDC is tracking an outbreak of E. coli from an unknown source that has affected people in four states, including Indiana.

The Centers for Disease Control announced Friday that it is looking into the outbreak, which they said was caused by an unknown food source. 37 illnesses have been reported so far, according to the CDC’s website, with 10 of them resulting in hospitalization.

The four states the CDC listed as being affected are Michigan, Ohio, Pennsylvania and Indiana. Ohio has recorded the most cases at 19, with Michigan reporting 15 cases, two reported cases in Pennsylvania and one case in Indiana.

“The true number of sick people in this outbreak is likely higher than the number reported, and this outbreak may not be limited to the states with known illnesses,” the CDC website reads. “This is because many people recover without medical care and are not tested for E. coli.”

Illnesses began being reported on July 26 and so far those infected have ranged from 6 to 91 years old. The median age of those infected, the CDC said, is 21 and 64% of cases affected males.

Of the ten people who the CDC said have been hospitalized, three were in Michigan and patients “have developed a type of kidney failure called hemolytic uremic syndrome”. No deaths have been reported so far.

The closest connection amongst all cases the CDC has found? Wendy’s.

Out of the 26 people who have been interviewed, 22 said they ate at a Wendy’s within the week before their illness started. The Wendy’s locations where sick people ate are in Michigan, Ohio and Pennsylvania.

“People reported eating a variety of menu items, including burgers and sandwiches,” a CDC report reads. “Romaine lettuce served on burgers and sandwiches at Wendy’s was one of the most common ingredients eaten among the menu items, but investigators continue to analyze data at the ingredient level to determine if there are any other possible foods that could be the source of the outbreak.”

The CDC added that Wendy’s will stop offering romaine lettuce in the areas where these cases have been reported “as a precautionary measure” and that a different type of lettuce is used in their salads. They also said that Wendy’s has been fully cooperating with the CDC investigation.

According to the CDC, most people become infected with E. coli after eating contaminated food.

“Escherichia coli (E. coli) is a bacteria that normally is an important part of the healthy intestinal tracts of humans and animals,” the CDC’s website says. “However, there are some kinds of E. coli that are harmful and can cause disease.”

E. coli symptoms include the following:

  • watery or bloody diarrhea
  • fever
  • abdominal cramps
  • nausea
  • vomiting.

Anyone who believes they may be infected with E. coli is urged to immediately contact their doctor for an evaluation, the CDC said.