NOTE: The video is from a previous report.
Two of the hospitalized patients had hemolytic uremic syndrome, a serious complication that can develop from an E. coli infection. The older adult who died had underlying conditions but did not develop this syndrome.
The CDC opened the investigation on Tuesday, initially reporting 49 cases in 10 states - including 10 hospitalizations and one death. It can take weeks to determine whether an illness is part of an outbreak and these numbers were expected to grow.
Most of the illnesses related to the outbreak continue to be in Colorado, according to the CDC. Michigan, New Mexico and Washington have also been added to the list of states with reported illnesses, along with Iowa, Kansas, Missouri, Montana, Nebraska, Oregon, Utah, Wisconsin and Wyoming. But the agency notes that the outbreak may go beyond those states.
Federal authorities say that they are still working to confirm the specific source of the bacteria, but the US Food and Drug Administration says that the slivered onions or beef patties on Quarter Pounder sandwiches are the likely source of contamination.
Among those who have been interviewed, all reported eating at McDonald's and the vast majority had eaten a beef hamburger, according to the FDA.
"The FDA is using all available tools to confirm if onions are the source of this outbreak," an agency spokesperson said in a statement. "This includes working with federal and state partners and the companies involved to collect and evaluate records and distribution information as part of our traceback investigation. FDA and state partners are also collecting onion samples for analysis."
McDonald's has taken Quarter Pounders off the menu in about a fifth of its stores. The company has stopped using the onions as well as quarter-pound beef patties in several states - Colorado, Kansas, Utah and Wyoming, as well as portions of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico and Oklahoma - while the investigation continues, the CDC said.
McDonald's supplier Taylor Farms has removed yellow onions from the market "out of an abundance of caution," the company said in a statement Wednesday, and distributor US Foods has issued a recall of four onion products due to "potential E. coli contamination."
The FDA confirmed that yellow onions from Taylor Farms were sold to additional food service customers. Some other major fast food chains who have received onions from Taylor Farms - including Burger King, Taco Bell, Pizza Hut and KFC - have removed fresh onions from their menus at some locations.
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