As McDonald's E.coli outbreak expands, find the best ways to prevent and treat an infection.

It practically didn't matter where you shopped: if you bought organic carrots in late summer and early fall this year, you had to throw them out unless you were willing to risk getting infected with E. coli.

That's what the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) advised in a Nov. 16 recall announcement of Grimmway Farms organic carrots. To date, 39 people in 18 states have gotten sick.

The thing is, you might not have known you bought Grimmway Farms carrots, but if you bought the store brands of Whole Foods, Trader Joe's, Wegmans, Target and others, you did. All those stores repackage Grimmway's carrots as their own, and were thus subject to the recall.

Indeed, the recall makes clear something that might have been known only to ultra-savvy shoppers: a lot of the meat and produce that ends up on grocery store shelves under different store or "private" brand labels comes from the same, centralized producers. That means when there is contamination of one of these food items, shoppers of many different stores across the country are affected, and the already lengthy task for health agencies to track down the culprit of the contagion is trickier.

"We see this with a lot of recalls, right?" says Donald Schaffner, chair of the Department of Food Sciences in Rutgers School of Environmental and Biological Sciences. "Where you go and you say it's this store brand but there's all these other names or store brands because this company was manufacturing stuff under a variety of different labels and package types and things like that."

Store-brand meat and produce (and all store-brand products, really) are enticing to shoppers because they're typically lower in cost than brand name options. Sometimes, even, they are the brand name option; Grimmway organic carrots, for instance, are sold as store-brand products at many stores, but they're also sold as Cal-Organic and Bunny Luv brand carrots. You might see them side by side at different price points.

But determining just how centralized other items of produce are is a little tricky. The Cornucopia Institute, a nonprofit watchdog of the organic foods industry, notes that a national retailer might source from several regional farms throughout the year, meaning that "a single store brand could come from numerous sources over time."

Schaffner notes that this lack of transparency extends to items throughout your local grocery store.

"I would say that's not just true for produce but it's true for a lot of our food supply," he says. "Anything that's store-brand, the store is not manufacturing that. They're going to co-packers or co-manufacturers. And it's true for their deli items as well, sometimes. If they have a hot bar and things like that, they're not making all of that in the back of the house, so there has to be companies out there that are doing it."

Because retailers aren't required to specify which specific farm their produce came from, recalls offer a glimpse into just how much crossover there is between where stores get their food.

In 2023, Sunrise Growers Inc. issued a recall of frozen fruit products that were in store-brand products at Whole Foods, Target, Aldi, Walmart and Trader Joe's. In 2022, Old Europe Cheese Inc. issued a recall of the brie and camembert it sells under various brand names -- Primo Taglio, La Bonne Vie, Joan of Arc -- and store brands, namely Target and Trader Joe's. And in 2023, HMC Farms recalled peaches, plums and nectarines sold at Walmart and Sprouts in seven states.

In the last three years, the FDA has recorded 28 recalls of foods sold under multiple store and brand names. It's possible, Schaffner says, that due to developments in food testing systems, that we're catching the sources of foodborne illness more often than before.

"To a certain extent, we have an increasingly centralized food system and so if there is a problem in that system, then it gets magnified," Schaffner says. "When outbreaks happen, they tend to be big and CDC is good at now putting these pieces together and with advances in this whole genome sequencing approach, maybe we're seeing outbreaks we might've missed before."

Make no mistake, it's good that state and federal health authorities caught the E. coli outbreak in Grimmway Farms' organic carrots. However, the recall notice wasn't issued until weeks after the carrots in question were already off the shelves -- either because retailers pulled them or because people bought them and currently have them in their refrigerators.

That delay is inherent in the system, says Dr. Edward Lifshitz, medical director of the Infectious and Zoonotic Disease Program at the NJ Department of Health (NJDOH). Consider how an outbreak of E. coli, listeria, salmonella or another foodborne illness might be caught.

A person needs to consume the infected product. They then need to get sick from it, which is not nearly always the case. They need to be sick enough to see a doctor (again not always the case), and the doctor needs to suspect something like food poisoning to then order a stool sample. The sample, if it comes back positive, is then sent to the CDC, which sequences the DNA and compares it to other samples that have come in from around the country to determine if there's any commonalities.

Then, health departments need to go interview the sick people -- as the NJDOH did for the two people in New Jersey who were sickened by carrots -- to determine what they ate a few days before they got sick. That's not easy; can you remember everything you ate three weeks ago?

Eventually, and hopefully, enough people who tested positive for the same illness say they ate the same thing and the disease can be traced back to its origin. But there are obstacles at every step of the way during the weeks-long process.

"If you go to the doctor an awful lot of the time that doctor will say, 'It's probably one of these things, let me give you an antibiotic,' and no testing is done," Lifshitz says. "Public health wouldn't find out information from that. We wouldn't get information until that doctor is suspicious enough [to] do a stool culture. ... Once we get that positive result, the local health department, we go out and we interview that person and say, 'OK, we know you have a positive stool culture for E. coli, let's figure out where you could've gotten it from,' but we're now two weeks after when that person ate that."

Though many people may eat food included in a recall, not everyone will get sick. It's the folks with pre-existing health issues and/or weakened immune systems that bear the brunt of such situations. Time is of the essence in these cases, Lifshitz says.

"Is it disheartening, basically, that it takes weeks before we have an idea that it is real enough to give people a heads up as to what might be causing a problem? Yeah, absolutely," he says. "Especially for an item like this where those contaminated carrots -- assuming it was carrots -- are off the shelves already. It might still be in some people's homes. We'd like to look at that a whole lot earlier. Really, for all the stuff that has to happen before you get to a point where you get an idea about what might be causing it, it's really difficult to do that any faster."

Schaffner adds that, typically, when there is an outbreak, it is the result of a "perfect storm" of causes in the harvesting, production and processing pipeline. The FDA is charged with inspecting produce operations, but they're only required to do an inspection once a year -- though sometimes third-party inspectors, like those sent from the national retailers buying those foods, may do further inspections.

That is to say, the work done to track down the culprits of foodborne illnesses are vital to ensuring public health.

"In one way, not to be an apologist, but it shows the system is working because we're finding these outbreaks, but certainly the fact that there are outbreaks is concerning," he says.

At the very least, one could say changes are afoot in the agricultural space. The incoming Trump administration and the pick for Secretary of the Department of Health and Human Services, Robert F. Kennedy, Jr., have hinted at changes to everything from subsidies for industrial farms to cutting regulatory budgets.

Maybe that means national retailers will look to source produce locally -- and, to be clear, many do when it's seasonally appropriate and economically viable. And rules that require retailers to print exactly where their food was grown would be welcome for many in the food and health space.

But the baseline hope is that the safeguards the CDC and FDA have in place continue to get budgetary support, Lifshitz and Schaffner say.

"Obviously food safety is important," Schaffner says. "What CDC does is important, what FDA does is important. Most of that work is not done by political appointees, it's done by bureaucrats or scientists, boots on the ground. [...] Obviously if people are concerned about this, they should speak up. Certainly it's everybody in my community; we're talking about this too, because we see what might be coming."

"It is the FDA that has the authority and the ability to go in and do inspections and other things related to food," Lifshitz adds. "So certainly we rely very heavily on our federal partners, and we would be concerned if anything happened that restricted their ability to function.