US fast-food chains pulled onions from menus after McDonald's E. coli outbreak

At least 49 people in 10 US states have been sickened by contaminated food, according to health authorities.

US fast-food chains including Burger King, KFC and Taco Bell have pulled fresh onions from some restaurants after an E. coli outbreak linked to McDonald's quarter pounder sandwiches sickened dozens of people.

Burger King's parent company, Restaurant Brands International, and Yum Brands, which operates Taco Bell, Pizza Hut and KFC, made the announcement Thursday as McDonald's named a California-based supplier as the source of onions linked to food poisoning.

Illegal Pete's, a Mexican fast-food chain based in Colorado, also announced it was temporarily pulling several menu items, including onions.

Taylor Farms, based in Salinas, Calif., did not immediately respond to a request for comment.

McDonald's pulled its Quarter Pounder from one of its five US outlets after the Centers for Disease Control and Prevention (CDC) linked the item to food poisoning cases in 10 states earlier this week.

At least 49 people have become ill, mostly in Colorado and Nebraska, including one elderly adult, according to health authorities.

Authorities have identified the bacteria behind the illness as E coli O157:H7, which causes more than 2,000 hospitalizations and 61 deaths in the United States each year, according to the CDC.

Symptoms of E. coli poisoning can appear within a day or two of consuming contaminated food and usually include fever, vomiting, diarrhea, and symptoms of dehydration.

E coli is especially dangerous for young children and the elderly, pregnant or those with weakened immune systems.