E. Coli outbreak connected to McDonald's Quarter Pounders increases to 75 cases across 13 different states in US

The number of cases in a deadly E. coli outbreak linked to McDonald's Quarter Pounders has risen to 75, according to new federal data released on Friday, October 25.

Cases have been reported in 13 states in the US, according to the Centers for Disease Control and Prevention (CDC).

Most of the cases have been in Colorado, which has 26 reported cases, and Montana, which has 13 reported cases, according to the CDC.

Cases have also been reported in Iowa, Kansas, Michigan, Missouri, Nebraska, New Mexico, Oregon, Utah, Washington, Wisconsin and Wyoming, according to the CDC, which further notes that illnesses have occurred between Sept. 27 and Oct. 10 of this year.

Of the 61 people about whom the CDC has information, 22 have been hospitalized, and two developed hemolytic uremic syndrome, a serious, potentially fatal complication of E. coli infection that can cause kidney failure, according to the CDC.

One death has been reported in Colorado in connection with the outbreak. The person was a resident of Mesa County in the western part of the state, according to the Mesa County department of health.

"The true number of sick people in this outbreak is likely much higher than the number reported, and the outbreak may not be limited to the states with known illnesses," the CDC said in its update. "This is because many people recover without medical care and are not tested for E. coli. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak."

McDonald's says either fresh, slivered onions or beef patties used for the Quarter Pounder may be behind the outbreak.

Following the initial announcement of the outbreak on Tuesday, the fast-food company announced it had proactively removed two ingredients from stores across two affected regions. The company's leadership team said that a majority of other menu items are not impacted, according to the CDC investigation.

McDonald's confirmed in a statement to ABC News that Taylor Farms is the supplier of the sliced onions the fast-food chain removed.

The U.S.Food and Drug Administration (FDA) is investigating but has not definitively stated the source of the E. coli, although they have said that the onions are a “likely source of contamination.”

Taylor Farms issued a voluntary recall on Wednesday for its raw onions.