NEW YORK - One person has died and dozens were sickened from E. coli infections linked to McDonald’s Quarter Pounder hamburgers in 10 states, the US Centres for Disease Control said on Oct 22.

The E. coli outbreak, linked to one of McDonald’s most popular menu items, has sickened 49 people and sent 10 to the hospital, officials say.

The strain involved, E. coli O157:H7, can cause serious illness and was the source of a 1993 outbreak that killed four children who ate undercooked hamburgers at Jack in the Box restaurants.

Shares of the world’s largest fast-food chain were down about 6 per cent in extended trading.

A livestock trader said the outbreak also could pressure US cattle futures on Oct 23 by threatening demand for beef.

Everyone interviewed has reported eating at McDonald’s before their illness started, and most mentioned eating a quarter pounder hamburger, according to the CDC.

The specific ingredient linked to the illness has not yet been identified but investigators are focused on fresh, slivered onions and fresh beef patties, the CDC said.

Most of the illnesses were reported in Colorado and Nebraska.

“The initial findings from the investigation indicate that a subset of illnesses may be linked to slivered onions used in the Quarter Pounder and sourced by a single supplier that serves three distribution centres,” McDonald’s North America Chief Supply Chain Officer Cesar Piña said in a statement.

McDonald’s has proactively removed the slivered onions and beef patties used for the quarter pounder hamburgers from stores in the affected states while the investigation continues, the company informed the CDC.

Top US food safety attorney Bill Marler, who represented a victim in the Jack in the Box outbreak, said onions are the most likely source of contamination and have been linked to prior E. coli O157:H7 outbreaks.

Beef seems unlikely, because those outbreaks have become uncommon due to food safety measures, said Mr Marler, a founder of Marler Clark in Seattle.

“You’d have to have multiple restaurants under cooking the meat,” said Mr Marler, who expects to see more cases reported in the outbreak.

McDonald’s is temporarily removing the Quarter Pounder from restaurants in the impacted area, including Colorado, Kansas, Utah and Wyoming, it said in a statement, adding it was working with suppliers to replenish supply in the coming week.

Symptoms for E. coli include severe stomach cramps, diarrhoea and vomiting.

In 2015, burrito chain Chipotle saw its sales battered and reputation hit due to E.coli outbreaks in several states.

That outbreak was linked to the E. coli O26 strain that usually causes less severe illness than E. coli O157:H7.

Source: Reuters