Donald Trump wasn't the worst thing to happen to McDonald's this week.

Maybe Donald Trump's stunt that made the drive-thru “work” was a bad omen for Mickey D's: Now On E.coli The outbreak linked to the franchise's famous Quarter Pounder has infected at least 49 people and resulted in the death of one person with underlying medical conditions. Most of the illnesses occur in Colorado and Nebraska, and there are also isolated cases in eight surrounding states.

Of food-borne diseases E.coli Infections are more serious, says Laura Gieraltowski of the Food, Water and Environmental Diseases Division of the Centers for Disease Control and Prevention. They are particularly dangerous for young and elderly people, as well as for people with weakened immune systems and about 5 to 10 percent of people who are infected with them E.coli A complication called hemolytic uremic syndrome occurs and can sometimes be fatal. This outbreak hospitalized 10 people, including a child with HUS. However, most infected people recover at home without ever seeking medical attention.

E.coli Outbreaks occur fairly regularly – up to 50 E.coli Outbreaks are reported to the CDC every year, with 5 to 15 of them, like this one, affecting multiple states. (There was also a case involving raw cheddar cheese in February and one involving organic walnuts in April.) Yikes, right? Let's talk about it.

How works E.coli even come to eat?

E.coli is a group of bacteria that tend to reside in the large intestines of animals (hence). coli), making it perfect for excreting an infected person in their feces. It can then either enter our food system directly (vegetables in a field become contaminated with animal feces) or through the environment (rain and wind pick up fecal residue and contaminate food or water), explains Matt Stasiewicz, a food safety scientist at the University of Illinois in Urbana Champaign.

E.coli are really the enemy here!

No, actually. Most types of E.coli Bacteria are benign and even a healthy part of our digestive system. There are six species that cause gastrointestinal distress in humans, with symptoms including vomiting, fever and bloody diarrhea. So if you hear about it E.coli It's one of them in the news. Much E.coli simply exist silently.

How did the CDC figure out that the Quarter Pounder was the culprit food?

After an outbreak begins in multiple states, the CDC goes to infected people and records their current food history. In this case, “a larger proportion of these people report eating at McDonald's, and in particular eating the Quarter Pounder menu item, than we would normally see in a given week in the United States,” says Gieraltowski.

So that gave the CDC a pretty good indication that the “Quarter Pounder” menu item was to blame. From there, the agency narrowed down the ingredient that was most likely contaminated. The only unique ingredients in a Quarter Pounder that aren't used anywhere else on the menu are the beef patties and the sliced ​​fresh onions.

Ah, so it was definitely the beef, right?

You could say so! But actually, beef is much less likely to cause foodborne illness outbreaks these days, Stasiewicz says. In the 1990s, outbreaks related to undercooked meat were common, particularly in fast food chains. Many lawsuits later, “the fast food industry and the beef industry as a whole have done a really good job of solving this problem,” he says. “They fixed the system and now we have really good meat cooking practices.”

That may explain why McDonald's and health officials view onions as the more likely culprit. Fruits and vegetables have become an increasingly important issue in the world of food safety. It's easy to kill E.coli in meat: Just cook the protein well. But it is more difficult to eliminate it 100 percent E.coli in things we eat raw, such as fruits and vegetables. “They don’t have a kill step,” Stasiewicz says. “Basically, you have to prevent contamination.” There are many regulations for this.

Uh, how about washing the produce?

Running water can help wash away contaminants, but it's not enough to kill the bacteria, let alone remove much of it. For this reason, washing produce is always a good idea, but it's not foolproof. There are simply a lot of microorganisms in the world and it is difficult to stop them E.coli from sneaking through. (However, a very effective way to reduce cross-contamination is to not use the same knife or cutting board for raw meat and vegetables.)

I'm going to avoid McDonald's for a while.

Sure, you can. But there's probably no reason to worry about McDonald's specifically right now. The Quarter Pounder has been removed from the menu in affected states and will return “in the coming weeks,” according to updates from the fast food chain. (It's still available in other states.) “People can still eat at McDonald's; You can still eat onions and burgers in other places,” says Gieraltowski. “These burgers are temporarily not for sale, so the risk to the public beyond this is low.”

Additionally, the contaminated ingredient came from a supplier — possibly Taylor Farms in California, a single supplier that supplies McDonald's with its raw onions, the Food and Drug Administration said Thursday. Taylor Farms has since issued a recall for four raw onion products. So it's not like there's anything particularly disgusting about McDonald's, and you don't have to worry about raw onions in general either.

When it comes to deciding which foods are safe to eat, “it's really hard to play the role of detective in your own head because most consumers don't know enough about the supply chain,” says Stasiewicz. By the time we learn something is contaminated, the CDC has already taken mitigation measures. All we can really do is follow the specific instructions included.

Still, this has to have an impact on McDonald's, right??

It's not a great look. The stock fell more than 5 percent on Wednesday, marking its worst day since March 2020. According to Reuters, analysts say it is too early to estimate how much of an impact this will have on the chain's fourth-quarter sales. But such a decline in inventories is fairly normal after outbreaks. A key example: Chipotle, which experienced multiple outbreaks between 2015 and 2018, lost two-thirds of its value. By 2019, the stock had recovered and reached an all-time high.

Of course, McDonald's emphasizes that its food is safe and encourages people to still visit its restaurants.

Where does the investigation go from here?

The FDA and the U.S. Department of Agriculture will continue their investigations by tracing backwards – starting with the suspected contaminated ingredients, through the suppliers of those ingredients, then to the farms, etc., where they test the products there. They will also work with suppliers to figure out where else the onions or beef ends up other than McDonald's.

“It is very plausible that we will not get the complete answer,” says Stasiewicz. “Most outbreaks of foodborne illnesses remain completely unsolved.” (For foodborne infections in several states, the CDC identifies the carrier of the illnesses in about 60 percent of outbreaks.) Regardless, the more you find out, the more can be done to prevent the next ones Outbreak.