A California-based produce company was the source of scallions linked to deadly E. coli food poisoning epidemic This happened at McDonald’s on Thursday, restaurant chain officials said. Meanwhile, other fast food restaurants such as Taco Bell, Pizza Hut, KFC and Burger King have also removed onions from some menus.

McDonald’s officials said Taylor Farms in Salinas, Calif., had shipped onions to a distribution facility, causing a major crisis for the fast food chain. Put away Quarter Pounder burgers from restaurants in various states. McDonald’s did not say which facility.

An outbreak linked to burgers has sickened at least 49 people in 10 states and killed one among them, federal health officials said. Investigators said they were focused on sliced ​​onions as a potential source of infections

US Foods, a leading wholesaler to restaurants across the country, said Thursday that Taylor Farms is recalling peeled whole and diced yellow onions this week due to potential E. coli contamination. A US Foods spokeswoman said the recalled onions came from the Taylor Farms facility in Colorado. But the wholesaler also said it is not a McDonald’s supplier and that its recall does not involve any products sold at the fast food chain’s restaurants.

Taylor Farms did not respond to multiple requests for comment.

U.S. Food and Drug Administration officials have not confirmed that the agency is investigating Taylor Farms. The agency is “looking at all sources” of the outbreak, a spokesman said Thursday.

Meanwhile other national restaurant chains temporarily stopped using spring onions.

“As we continue to monitor the recently reported E. coli outbreak and out of an abundance of caution, we have proactively removed scallions from select Taco Bell, Pizza Hut and KFC restaurants,” Yum Brands said in a statement.

Yum Brands, based in Louisville, Kentucky, did not say where the onions were sourced or whether the company uses the same supplier as McDonald’s. Yum Brands said it will continue to follow guidance from regulators and its suppliers.

Restaurant Brands International, which owns Burger King, said Thursday that 5 percent of its restaurants use onions distributed by Taylor Farms’ Colorado facility. Burger King restaurants receive whole spring onions and their employees wash, peel and slice the onions.

Restaurant Brands said it asked restaurants that received onions from the Colorado facility to destroy the onions two days ago, even though it had not been contacted by health officials and there were no signs of illness. The company said it is restocking with onions from other suppliers.

Chipotle said Thursday that it does not source onions from Taylor Farms or any other ingredients from the Colorado facility.

onions mixed previous epidemics. Taylor Farms recalled the celery and onion mixture used in Costco’s chicken salads after 19 people contracted E. coli disease in 2015. Last year, 80 people got sick, 1 person died Salmonella poisoning outbreak linked to bagged chopped onions from Gills Onions in Oxnard, California.

At least 10 people were hospitalized due to the McDonald’s outbreak, including a child who suffered serious kidney disease complications as a result of the infection. The illnesses were confirmed between September 27 and October 11, according to the U.S. Centers for Disease Control and Prevention.

The victims were infected with E. coli 0157:H7, a type of bacteria that produces a dangerous toxin. It causes about 74,000 infections annually in the United States, leading to more than 2,000 hospitalizations and 61 deaths each year, according to the CDC.

A Greeley, Colorado man is suing McDonald’s after contracting an E. coli infection. In a lawsuit filed this week, Eric Stelly said he ate at the local McDonald’s on Oct. 4 and became ill two days later. After seeking emergency care, health officials confirmed the infection was part of the outbreak.

Symptoms of E. coli poisoning can appear quickly, within a day or two after consuming contaminated food. These usually include fever, vomiting, diarrhea or bloody diarrhea, and signs of dehydration (little or no urination, increased thirst, and dizziness). The infection is especially dangerous for children under 5 years of age, the elderly, pregnant women, or people with weakened immune systems.

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