Federal Health officials on Friday said at least 75 people across 13 states have been sickened by the recent and deadly E. coli outbreak linked to McDonald’s Quarter Pounder hamburgers. 

The U.S. Centers for Disease Control and Prevention confirmed one fatality linked to the outbreak, as had been previously reported. At least 22 people have been hospitalized, and two people developed hemolytic uremic syndrome (HUS), a serious health issue that can cause kidney failure. The person who died, an older person from Colorado, isn’t one of the people who developed HUS, the health agency said.

Federal health officials alerted the public to the outbreak on Tuesday, and McDonald’s removed the product from about a fifth of its 13,000 U.S. locations, including its restaurants in Colorado, Kansas, Utah, Wyoming and parts of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico and Oklahoma.

Illnesses started on September 27, with the last reported case on October 10, according to health officials. States with cases include:

• Colorado
• Iowa
• Kansas
• Michigan
• Missouri
• Montana
• Nebraska
• New Mexico
• Oregon
• Utah
• Washington
• Wisconsin 
• Wyoming

McDonald’s sold about 1 million Quarter Pounders in the timeframe that the illnesses occurred, a spokesperson for the restaurant said, adding that the fast-food chain believes more people would have been sickened if the contamination stemmed from the patties themselves, adding that onions used on the burgers may be the culprit.

McDonald’s burgers are cooked at 175 degrees, above the 160 degree level needed to kill the E. coli bacteria, while the sliced onions are raw, the spokesperson explained.

“If that is the source, it will be the first time onions have been a carrier for this strain of E. coli,” the spokesperson said.

Of the people the who told the CDC they got sick after eating at McDonald’s, nearly all said they had eaten a beef hamburger, with most specifying it had been a Quarter Pounder. Some of those who were stricken reported traveling to other states before they became ill, with at least three eating at McDonald’s during their travel, the federal agency noted.

Investigators continue to work to confirm if slivered onions or beef patties in the burgers are the source of the E. coli outbreak. Preliminary findings reviewed by the Food and Drug Administration Administration show that slivered onions are a likely source. The FDA is also working to determine if the onions were served or sold at other businesses. 

The supplier of the onions for the affected McDonald’s locations is California-based produce giant Taylor Farms, which initiated a recall of yellow onions produced at its Colorado facility.

“As a family-owned business we take pride in providing safe, healthy fresh foods to people every day. It saddens us to see the illnesses and affected individuals and families from the current E. coli O157:H7 outbreak,” a Taylor Farms spokeswoman told CBS News in an email, referring to the particular strain behind the current spate of illnesses.

“Our thoughts and prayers go out to the individuals and their families impacted. Our priority remains the health and safety of our consumers. We have preemptively recalled yellow onions from our Taylor Farms Colorado facility that were sent to select foodservice customers,” she added.

The company is working with CDC and FDA to determine the course of the E. coli outbreak, the spokesperson said.

The potential for contamination prompted Burger King, KFC, Taco Bell and other major fast-food chains to pull fresh onions from some of their own locations, although the restaurants stressed they had no indications of illness. 

E. coli symptoms

It typically takes three to four weeks to determine if a sick person is part of an outbreak. Those infected with the toxin-producing E. coli experience severe stomach cramps, diarrhea and vomiting, and most recover without treatment after five to seven days.

People are advised to call their health care provider if they ate a McDonald’s Quarter Pounder and have severe E. coli symptoms, as follows: 

• Diarrhea and a fever higher than 102°F
• Diarrhea for more than 3 days that is not improving
• Bloody diarrhea
• So much vomiting that you cannot keep liquids down
• Signs of dehydration, such as:
• Reduced urination
• Dry mouth and throat
• Feeling dizzy when standing up

The health worries about one of McDonald’s most popular menu items comes as fast-food chains try to attract consumers still smarting from high food prices. The company this summer launched a $5 value meal in a bid to draw lower-income customers.

The outbreak is not the first to be linked to the Golden Arches. In 2018, an outbreak of intestinal illness linked to salads from McDonald’s sickened more than 500 people in more than a dozen states.

McDonald’s shares were down 2.5% on Friday, or down 1% for the year.