The CDC has named slivered onions processed by Taylor Farms and served on McDonald’s Quarter Pounders as the source of illnesses in a deadly E. coli O157:H7 outbreak.

Both the Food and Drug Administration and the Centers for Disease Control and Prevention had previously suspected onions of being the culprits.

As of Oct. 30, there were 90 confirmed patients, up from 75 reported earlier in the week. Another five patients have been hospitalized, bringing that total to 27. Two people have developed hemolytic uremic syndrome (HUS), a serious condition that can cause kidney failure. One patient died but had not developed HUS.

The onset dates of illness began on Sept. 27, with the most recent person becoming ill on Oct. 16. Of the 62 people interviewed, all 62 reported eating at McDonald’s.

The sick people are spread across 13 states. The patients range in age from 13 to 88. The states with sick people are Colorado, Kansas, Utah, Wyoming, Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, and Oklahoma. 

According to the CDC, additional patients are expected to be identified because diagnosis can take up to four weeks. 

Also, there are likely many more outbreak patients than the CDC total reflects because for every single person diagnosed, there are an estimated 26 others who go undiagnosed. This is because some patients do not seek medical attention, and others are not explicitly tested for E. coli infection, which can mimic other illnesses. 

Taylor Farms of Salinas, CA supplied the implicated onions. On Oct. 22, the company issued a recall for its food service customers of whole, peeled, and diced onions. According to the CDC, the FDA has initiated inspections at a Taylor Farms processing facility in Colorado and at a Washington state farm “of interest. ” 

Onions have been the source of pathogens in previous outbreaks. In 2015, Taylor Farms recalled a celery and onion mix used in Costco chicken salads after 19 people were sickened with E. coli. 

The beef patties used for the McDonald’s hamburgers involved in the current outbreak have been ruled out as a source of the pathogen.

“On Oct. 22, the Colorado Department of Agriculture laboratories analyzed subsamples from all the lots of McDonald’s brand fresh and frozen beef patties collected from various McDonald’s locations in Colorado and found them negative for E. coli. All beef has been completed,” according to the CDC.

McDonald’s temporarily stopped serving Quarter-Pound sandwiches in some states after the outbreak was discovered but has since begun reintroducing them.

About E. coli infections
Anyone who has eaten at McDonald’s and developed symptoms of E. coli infection should seek medical attention and tell their doctor about their possible exposure to the bacteria. Specific tests are required to diagnose the diseases, which can mimic other illnesses.

The symptoms of E. coli infections vary for each person but often include severe stomach cramps and diarrhea, which is often bloody. Some patients may also have a fever. Most patients recover within five to seven days. Others can develop severe or life-threatening symptoms and complications, according to the Centers for Disease Control and Prevention (CDC).

About 5 to 10 percent of those diagnosed with E. coli infections develop a potentially life-threatening kidney failure complication known as a hemolytic uremic syndrome (HUS). Symptoms of HUS include fever, abdominal pain, tiredness, decreased frequency of urination, small unexplained bruises or bleeding, and pallor. 

Many people with HUS recover within a few weeks, but some suffer permanent injuries or death. This condition can occur among people of any age but is most common in children younger than five years old because of their immature immune systems, older adults because of deteriorating immune systems, and people with compromised immune systems such as cancer patients. 

People who experience HUS symptoms should immediately seek emergency medical care. People with HUS will likely be hospitalized because the condition can cause other serious and ongoing problems such as hypertension, chronic kidney disease, brain damage, and neurologic problems.

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