The Centers for Disease Control and Prevention announced Wednesday that the number of E. coli cases linked to McDonald’s Quarter Pounders has increased to 90, up from 75 reported last Friday.
The CDC said shredded onions in the hamburger were “likely” the source of the infection.
A McDonald’s spokesperson said Tuesday that Quarter Pounders had been removed from restaurants in the affected states by Oct. 22, when the outbreak was first announced. The CDC said the additional risk to the public is “very low.”
On Sunday, Colorado Department of Agriculture officials ruled out the possibility that beef patties used in Quarter Pounders were the source of the infection after tests found no trace of E. coli.
The outbreak has resulted in one death and 27 hospitalizations, according to the CDC. At least two people, including a 15-year-old girl in Grand Junction, Colorado, have developed a rare kidney disease called hemolytic uremic syndrome.
The high school freshman’s initial symptoms — fever and abdominal pain — began a few days after several trips to the local McDonald’s for Quarter Pounders. She experienced vomiting and bloody diarrhea.
She was then hospitalized with kidney failure and had to undergo multiple rounds of dialysis.
The actual number of infections linked to the Quarter Pounder is likely much higher than the 90 people reported so far. Most people with E. coli infections do not undergo bacterial testing and recover on their own.
Thirteen states have reported cases: Colorado, Iowa, Kansas, Michigan, Missouri, Nebraska, New Mexico, Montana, Oregon, Utah, Washington, Wisconsin, and Wyoming.
The Food and Drug Administration also said sliced onions supplied by food manufacturer Taylor Farms Colorado Springs were the most likely source of the contamination.
McDonald’s said 900 restaurants in 12 states received onions from Taylor Farms.
The restaurant chain announced Friday that it had indefinitely stopped sourcing onions from the company. The company plans to begin selling onion-free Quarter Pounders in affected stores this week.
Other Colorado restaurant chains, including Taco Bell, Burger King, KFC, Pizza Hut and Illegal Pete’s, have removed onions from their menus out of an abundance of caution. There is no indication that people have contracted E. coli after eating at these restaurants.
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