One person has died, and dozens have fallen ill from E. coli infections connected to McDonald’s Quarter Pounder hamburgers in 10 states, with Colorado seeing the highest number of cases, where 26 people have been affected, the U.S. Centers for Disease Control and Prevention (CDC) reported on Tuesday.
The outbreak, tied to one of McDonald’s most popular items, has resulted in 49 confirmed illnesses and 10 hospitalizations, according to health officials. The strain involved, E. coli O157:H7, is known to cause severe illness and was responsible for the 1993 Jack in the Box outbreak, which led to the deaths of four children who had eaten undercooked burgers.
McDonald’s shares dropped by roughly 6% in after-hours trading. A livestock trader also noted that the outbreak could potentially impact U.S. cattle futures by reducing demand for beef.
According to the CDC, all those interviewed during the investigation reported dining at McDonald’s before falling sick, with most mentioning they had eaten a Quarter Pounder burger. Investigators have yet to pinpoint the exact source of the contamination but are focusing on fresh beef patties and slivered onions.
Most of the cases have been reported in Colorado and Nebraska.
“Initial findings suggest that a portion of the illnesses may be linked to slivered onions used in the Quarter Pounder, which were supplied by a single vendor that services three distribution centers,” stated Cesar Piña, McDonald’s North America Chief Supply Chain Officer.
In response, McDonald’s has proactively pulled the slivered onions and beef patties used in Quarter Pounders from locations in the affected states as the investigation progresses, the company informed the CDC.
U.S. food safety lawyer Bill Marler, who previously represented a victim in the Jack in the Box case, warned that more illnesses could emerge. He added that onions have been linked to past outbreaks of E. coli O157:H7.
According to Marler, a founder of Marler Clark in Seattle, beef contamination is less common due to food safety measures. “You’d have to have multiple restaurants under-cooking the meat,” he said.
McDonald’s is temporarily removing the Quarter Pounder from restaurants in the impacted areas, 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, diarrhea and vomiting. Most people who suffer an infection will start feeling sick three to four days after eating or drinking something that contains the bacteria, Colorado’s public health department said. However, illnesses can start anywhere from one to 10 days after exposure, the department added.
In 2015, burrito chain Chipotle (CMG.N) saw its sales battered and reputation hit due to E.coli outbreaks in several states. That outbreak was linked to a different strain of E. coli that typically causes less severe illness than E. coli O157:H7.
In addition to Colorado, the CDC said small clusters of a few people fell ill after eating a Quarter Pounder in Nebraska, Utah and Wyoming. Kansas, Missouri, Oregon, Iowa, Wisconsin and Montana had one illness apiece.
