A severe outbreak of E. Coli linked to McDonald's Quarter Pounder burgers has expanded to 75 reported cases, mainly in the western United States, authorities said Friday.
The number of hospitalizations has risen to 22, though no additional deaths have been reported beyond that of an elderly patient in Colorado, according to the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC).
One child and one adult developed hemolytic uremic syndrome, a serious condition that damages blood vessels in the kidneys.
Investigators have yet to confirm a specific ingredient as the contamination source, though they are assessing whether slivered onions or beef patties could be the origin.
While the investigation is underway, Taylor Farms, which supplies the slivered onions to affected locations, has issued a voluntary recall of its yellow onions.
McDonald's restaurants in the 13 impacted states have temporarily pulled Quarter Pounders from their menus, though other items, including other beef burgers, remain available.
Shares of the fast-food giant dropped more than two percent in early afternoon trading.
Meanwhile, the law firms Ron Simon & Associates and Meyers & Flowers have filed lawsuits on behalf of two separate consumers from Colorado and Nebraska who fell ill after consuming the burgers.
Each suit seeks a minimum of $50,000 in damages, and attorney Ron Simon told AFP he plans to represent a total of 25 victims.
"When a consumer goes to McDonald's to buy a meal, they're placing an enormous amount of trust that McDonald's has done everything it can to make your food safe," said Simon.
"And here, whether it was faulty testing, faulty oversight, faulty handling, somehow poison got in that food, and trust is broken."
The CDC advised those who consumed a Quarter Pounder and developed symptoms of E. coli poisoning -- such as diarrhea, bloody diarrhea, a fever over 102 degrees Fahrenheit (38.9°C), and vomiting -- to seek medical attention.
Symptoms typically begin three to four days after exposure, and most individuals recover within five to seven days without treatment. However, some cases can become severe and require hospitalization.
McDonald's said in a statement Tuesday it had taken "swift and decisive action" and that food safety was its "top priority."
