The state of Colorado made news in the wrong way recently with news of an E. coli infection outbreak initially linked to McDonalds Quarter Pounder hamburgers. Ten of the 26 cases reported in Colorado as of Tuesday, Oct. 22, 2024, occurred in Mesa County on Colorado’s Western Slope, with one person there dying after being infected.
Public health experts have now traced the E. Coli outbreak to tainted yellow onions on the burgers, and cases have spread to at least 13 states, from Michigan to Washington. By Wednesday, Oct. 30, the number of cases stood at 90, with 27 hospitalizations, according to the Centers for Disease Control and Prevention (CDC). More cases are expected.
The outbreak illustrates the importance of surveillance of food-borne illnesses by the Colorado Department of Public Health and Environment and their counterparts in other states, said Dr. Michelle Barron, professor of medicine and infectious diseases at the University of Colorado School of Medicine on the Anschutz Medical Campus.
“I have high regard for them,” said Barron. “This case shows you the work they do. They were able to detect the outbreak and actually figure out where it is.”
We spoke to Barron to understand more about the E. coli bacteria, the detective work required to identify and mitigate an infection outbreak and to answer your top questions about food-borne illnesses.
What is E. coli?
It is Escherichia coli, a type of bacteria that dwells in our intestines. “We actually all have it, and so do animals,” Barron told Denver 7 News in an interview Oct. 23. In healthy individuals, E. coli generally coexists peacefully in the thicket of organisms in the gut. Problems can occur, however, if a person ingests food or drinking water that is contaminated with specific strains of the bacteria, Barron said.
There are six strains of E. coli that cause illness, according to CDC experts.
Is one of those strains the culprit in the recent outbreak?
Yes. It is O157:H7, which produces a toxin called Shiga, Barron said. Shiga toxin-producing E. coli, or STEC, “causes you to become acutely ill,” she said.
What are the symptoms of a Shiga toxin-producing E. coli infection?
As with infection from other E. coli strains, people have severe diarrhea and dehydration, Barron said. However, the Shiga toxin increases the risk of bloody diarrhea and fever. In rare cases, the infection can lead to hemolytic uremic syndrome (HUS), which can cause blood pressure to plunge and lead to kidney failure and sepsis, she added.
“This strain of E. coli can make you much sicker and has the potential to put you in the hospital because of HUS,” Barron said. She noted that the same strain infected hamburgers at Jack in the Box restaurants in Washington State in 1993, sickening hundreds and killing four children.
“We try to get people to understand that if you are not getting better, and you still have fever and blood in your stool, you probably need to get checked,” Barron said. The longer the symptoms persist, the greater the risk of hospitalization or even death, she added.
How are E. coli outbreaks like the one that began in Colorado identified and tracked, to prevent even greater spread?
It begins when an individual visits their medical provider and receives a stool test that confirms an infection, Barron said. Shiga toxin-producing E. coli is on a list of organisms that requires reporting to the Colorado Department of Public Health and Environment (CDPHE), which has a section that works on tracking food-borne illnesses. In turn, CDPHE is part of a nationwide CDC network of public health agencies that track bacteria that cause illness, including E. Coli, salmonella, hepatitis A, Listeria and others
Individuals who have been infected provide demographic information and answer questions that help public health professionals probe where the infection may have originated, such as a wedding, a coffee shop, or with food purchased at a grocery store, Barron said. All of the information goes into the CDC’s national database. The details allow the painstaking work that isolates the cause of the infection.
In the McDonald’s case, the common thread – unraveled after more than three weeks – turned out to be the Quarter Pounder, but investigators still had to figure out what was unique about that particular burger that people consumed, Barron said. Was E. coli-containing ground beef undercooked? That possibility is still under consideration, but the likely culprit turned out to be fresh slivered onions layered on the Quarter Pounders – and only Quarter Pounders.
That conclusion, of course, led to the question of who supplied the onions. McDonald’s identified California-based Taylor Farms as the supplier. The CDC reported on Oct. 25 that Taylor Farms began recalling yellow onions and contacting stores to remove their products. Thus, the hard work paid off by preventing further disease spread.
Barron noted that the first case of an E. coli infection was reported Sept. 27, but at that point the cause was a mystery. “People will say, ‘How did you not know?’ I think it’s hard for people to see the work that goes into this, because all they see is the end point,” Barron said.
Can we expect to see more cases of E. coli infection linked to McDonald’s?
Yes. Between Tuesday, the 22nd and Thursday, the 24th, the number rose from 49 to 75.
“It can take three to four days after your exposure to develop symptoms,” Barron said. “Now that there is more awareness (of the outbreak), there are probably more people who will get tested.”
Others who have symptoms may not get tested, making it impossible to know the true number who were infected, she added.
Is there a treatment for an E. coli infection?
No, there’s no treatment for E. coli. In serious cases, however, providers can deliver IV fluids to treat dehydration and prevent kidney failure caused by toxins building up and triggering a massive immune response, Barron explained.
In addition, the CDC cautions that people infected with Shiga toxin-producing E. coli should not take medications for diarrhea because they increase the risk of HUS.
“If you suspect you have an infection with E. coli O157 based on symptoms of bloody diarrhea and fever, you should avoid taking antidiarrheal medications and just focus on drinking enough fluids,” Barron said. “Taking an anti-diarrheal medication increases your risk of developing kidney damage and other complications.”
Who is most vulnerable to an E. coli infection?
Older adults, very young children and people with weakened immune systems are most at risk, Barron said. “If you are relatively healthy and don’t have any other issues, you may feel sick, but it’s unlikely to cause you any [severe] problems.”
The CDC adds international travelers as a group are vulnerable to infection because of unsanitary food or drinking water they may encounter in countries they visit.
Can people spread E. coli?
Yes, particularly in high-contact professions, like food-handling, Barron said. “But within your own household, certainly there is also risk,” she added. “The most likely way you are going to transmit infection within your household or to others – outside of having a contaminated product – is by not following good hygiene practices.”
How can I protect myself from E. coli infection?
People can mitigate the risk by doing basic things like washing their hands, separating raw meats and vegetables during cooking, and avoiding touching food when they are feeling ill, Barron said. It is also important to wash and/or cook raw fruits and vegetables, as they are historically the main source of food-borne illnesses, she said.
“We want people to eat healthy, but it’s sadly ironic that it’s usually produce that gets us into trouble,” Barron said.