E.coli food poisoning linked to McDonald’s burgers has sickened at least 49 people in 10 US states, including one person who died and 10 who were hospitalised.

The death was reported in an older person in Colorado, while a child is in hospital with severe kidney complications, the US Centres for Disease Control and Prevention said on Tuesday (US time).

Infections have been reported in Colorado, Iowa, Kansas, Missouri, Montana, Nebraska, Oregon, Utah, Wisconsin and Wyoming.

Colorado has the most cases, 26, followed by Nebraska with nine.

Everyone interviewed in connection with the outbreak had reported eating at McDonald’s before falling ill and most mentioned eating Quarter Pounder hamburgers, the CDC said.

“McDonald’s Quarter Pounder hamburgers are making people sick, with most illnesses in Colorado and Nebraska,” it said.

The US Agriculture Department, the Food and Drug Administration and state health officials are also investigating.

E. COLI OUTBREAK: CDC is investigating 49 illnesses in 10 states linked to McDonald’s Quarter Pounder hamburgers. If you ate a Quarter Pounder hamburger from McDonald’s and have severe symptoms of E. coli, contact your healthcare provider. https://t.co/g87itkupCQ pic.twitter.com/gHzUKCnTi9

— CDC (@CDCgov) October 22, 2024

CDC Outbreak Response and Prevention Branch head Matt Wise told NBC News:, “This is a fast-moving outbreak.”

The first case occurred on September 27, followed by an unusual spike in E.coli cases reported in Colorado on October 10. The CDC started investigating on October 15.

A specific ingredient has not been identified as the cause, but investigators are focused on onions and beef.

A preliminary FDA investigation suggests that slivered onions served on the burgers are a likely source of contamination. The USDA is investigating the hamburger patties.

McDonald’s officials said initial findings suggested that some illnesses were linked to onions sourced from a single supplier.

The company has halted distribution of the slivered onions and temporarily removed the Quarter Pounder from menus in the affected states, and also in portions of Idaho, Nevada, New Mexico and Oklahoma.

“We take food safety extremely seriously and it’s the right thing to do,” the company said.

Wise said McDonald’s actions meant the overall risk to the public had reduced, but he suspected more illnesses would yet be reported.

E. coli bacteria are harboured in the guts of animals and found in the environment.

Infections can cause severe illness, including fever, stomach cramps and diarrhoea.

People who develop symptoms of E. coli poisoning should seek health care immediately and tell the provider what they ate. Symptoms can take three to four weeks to show.

The news comes in an already tough year for the Chicago-based McDonald’s chain.

Its global same-store sales fell for the first time in nearly four years in the second quarter as inflation-weary customers skipped eating out or chose cheaper options.

McDonald’s shares dropped 9 per cent in after-hours trading on Tuesday after the CDC’s announcement.

The type of bacteria implicated in this outbreak, E. coli O157:H7, causes about 74,000 infections in the US each year, leading to more than 2000 hospitalisations and 61 deaths.

Infections are especially dangerous for children younger than five and can cause acute kidney failure.

-with AAP