Contagious Conversations / Episode 50. Behind the Plate: Keeping Our Food Safe
Transcript
Cindy Ligon: It was the week before Christmas, I had plans to fly back to Nashville to see my 92-year-old mother. And on the 23rd, I called her and said, "I'm not going to be able to come. I'm sick. I'm so sick."
Claire Stinson: This is Cindy Ligon, a 66-year-old artist in Virginia, and right before Christmas, 2023, she got sick. It was a miserable ending to what had already been a miserable year for her.
Cindy Ligon: I both emotionally and physically, had just been through the wringer. I'd lost my husband suddenly in June of '23. We were married 23 years. He had health issues, so I was the healthy one, the strong one. And I always was the one who took care of other people, so it was really hard for me to be vulnerable and to be alone.
Claire Stinson: Now, on top of all that, her body was mounting a full-scale revolt.
Cindy Ligon: I'd never felt that ill. So ill, I could barely lift my head off the pillow. I had a fever of 101 and became nauseous and started throwing up. I didn't want to go to the hospital at Christmas. I didn't have anyone. I didn't want to impose on any of my friends to take me to the emergency room. I just thought, "I'm going to ride this out. It's got to be a virus."
Claire Stinson: Cindy took some flu medication, but it didn't help. For four days, she lay in bed only getting up to race to the bathroom until her nephew, a doctor, convinced her to go to the ER. Once she got there ...
Cindy Ligon: They got an IV started, I was dehydrated. And then, when I finally was examined, they were concerned. They put me in an isolation room. They were concerned it was a very contagious something.
Claire Stinson: Cindy didn't know it yet, and neither did the hospital staff. But what Cindy had wasn't the flu, and it wasn't an ominous virus from halfway around the world. It was actually a foodborne illness.
According to recent CDC research, one in six Americans will get sick with a foodborne illness this year. Roughly every three hours, an American dies from a pathogen like salmonella, listeria or norovirus. Recalls of contaminated foods have spiked in the last few years. They're up 20% since 2020.
Reporter 1: The FDA has increased a major recall warning for a popular brand of potato chips sold here.
Reporter 2: Recall for eggs sold across the state of Tennessee.
Reporter 3: Recall of more than 600 varieties of frozen waffles is expanding due to pancakes in Belgium.
Claire Stinson: But what had Cindy eaten that was making her so sick? And how many others were at risk of hospitalization or worse because they'd eaten it too?
Answering those questions requires a network of state, local, and federal public health authorities working together, doing high-tech data analysis and old-fashioned detective work.
On this episode of Contagious Conversations, we talked to an epidemiologist who helped crack Cindy's case. And take a closer look at how the public health system works to protect us from foodborne illness.
Josh Rounds: It's really a team sport, solving these outbreaks. And if you take out any piece of that team, you're not going to get to the answer.
Claire Stinson: We'll find out what these recalls tell us about the safety of our food and water systems. And how we can keep from being one of the estimated 48 million Americans who get sick with a foodborne illness this year.
Josh Rounds: For each case we hear about in surveillance, probably around 29 occur in the general population. That's just the tip of the iceberg.
Claire Stinson: I'm your host, Claire Stinson. Stay with us.
Up until about 120 years ago, Americans who wanted to avoid getting sick from something they ate or drank were basically on their own.The government had created the US Department of Agriculture back in 1862, but it was more focused on keeping boll weevils out of cotton crops than on regulating food safety.
But then along came Upton Sinclair. He went undercover at a Chicago meatpacking plant and wrote about the horrific conditions he saw there in his 1906 novel, The Jungle. The public was outraged and Congress responded by pushing through a bunch of new laws to protect Americans from unsafe food and medicines.
Ad Narrator: Meat is a favorite with almost everyone.
Claire Stinson: They put the USDA in charge of inspecting and regulating facilities that produce meat, poultry and eggs.
Ad Narrator: There's bologna, patties, scrapple, pork loaf, head cheese, liver pudding and other favorites. Just look for the mark of wholesomeness.
Claire Stinson: So the USDA was in charge of inspecting meat and poultry. Then Congress created the Food and Drug Administration, or FDA, to handle basically everything else from dairy products and packaged snacks to seafood and produce.
Today, more than 3000 state, local and federal agencies are involved in safeguarding our water supply and food system. These agencies range from public health departments out in rural Alaska to the nerve center of it all, the Centers for Disease Control and Prevention's headquarters in Atlanta.
One public health professional I talked to compared their work to a relay race where all these different agencies have to do their part and pass the baton to the next one. When you see a recall on the news, it means the relay race worked.
Regulating the food system is complicated because the system itself has gotten complicated in ways Upton Sinclair could have never imagined.
Josh Rounds: There's a lot of different foods, a lot of different ingredients going in a lot of different food items. And so trying to figure out which specific ingredient is causing an outbreak can be challenging.
Claire Stinson: This is Josh Rounds. While Cindy Ligon spent her Christmas vacation in an isolation room in Virginia, attached to an IV full of antibiotics, Rounds was 1,200 miles away in St. Paul, Minnesota, where he works as a foodborne epidemiologist.
Josh Rounds: So as a foodborne epidemiologist, part of my day-to-day role is to investigate foodborne illness. That can be the pathogens that are reportable to us, so things like salmonella, Shiga toxin-producing E. coli. And when people get sick with those and go to the doctor and test positive for them there, they report that to us and we'll investigate those cases.
Claire Stinson: Rounds has been a foodborne epidemiologist for 16 years. He says he's drawn to the work because it's something that affects all of us.
Josh Rounds: Foodborne diseases and outbreaks, I feel like they catch people's attention because everybody eats. I think the most recent CDC estimates were about 48 million people get sick each year. 128,000 get hospitalized and 3000 die from foodborne disease each year in the United States.
Claire Stinson: Most foodborne illnesses are isolated, localized events. Sometimes they're part of a larger outbreak. The challenge for epidemiologists like Rounds, is figuring out whether an illness is part of an outbreak, and what pathogen is making people sick. When people like Cindy get sick around the holidays, experts often suspect norovirus.
Josh Rounds: Some of the bacterial pathogens have a pretty distinct seasonality. It's like salmonella grows better in warmer temperatures, and then norovirus is really driven more by person-to-person transmission. Schools start up in the fall and people are congregated together really closely, and so we usually see that norovirus will start happening in fall, winter to spring.
Claire Stinson: But that snowy December of 2023, the Minnesota State Public Health Department was investigating a less common case of wintertime salmonella.
Josh Rounds: The way the system works, you have to get sick, decide to go seek healthcare, get tested, test positive. That's reported to us, and then we're trying to talk to you.
Claire Stinson: If solving an outbreak of foodborne illness is like a relay race, to stay with our track and field metaphor, this part is a little like running hurdles. And epidemiologists like Rounds run up against a lot of them. Hurdle number one, some people don't particularly like talking to the public health department.
Josh Rounds: Sometimes we get lucky in that we have a really good case that wants to talk to us, is able to provide really detailed information, and that's becoming more and more of a challenge. Our interview rates have declined during the pandemic and never really recovered back. But their participation in these investigations is really critical. Without their information, we wouldn't be able to figure out what's going on.
Claire Stinson: If the patient is gracious enough to talk, they quickly run into public health hurdle number two: remembering everything they ate that could have made them sick.
Josh Rounds: People usually associate their illness to the last thing they ate, when depending on the pathogen, the incubation periods for these diseases can be quite long. Salmonella can be from a day to seven days or sometimes even longer.
You can imagine if you try to think about what you had to eat a week ago. Unless you're really good, have a great memory, or you have a food diary, sometimes those people are out there. But for most of us, it's really hard to remember what you had to eat yesterday, let alone a few weeks ago.
Claire Stinson: As far as Rounds knew, his Minnesota salmonella case was just a one-off, like the vast majority of cases of foodborne illness are. But then his office got an email. It was from CDC, the Centers for Disease Control and Prevention.
Josh Rounds: We had a notification from CDC that there was a multi-state cluster that was detected, and there were 13 cases in five states.
Claire Stinson: CDC doesn't inspect meat packers like the USDA does, but the agency is an essential member of the relay team that keeps our food system safe, organizing as many as 36 investigations every week.
Josh Rounds: CDC plays a big role in coordinating multi-state outbreak investigations. So we are really quickly sharing information back and forth. That's the key part. And they're doing that critical role to help combine that exposure data from all the investigators.
Claire Stinson: The data he's talking about here is the genetic profile of samples taken from sick people like Cindy in Virginia. See, one of the technological breakthroughs that change the game when it comes to foodborne outbreak investigations is something called whole genome sequencing.
President Bill Clinton: We are here to celebrate the completion of the first survey of the entire human genome.
Claire Stinson: Whole genome sequencing made big news in the year 2000 when scientists finally mapped the entire human genome.
President Bill Clinton: Without a doubt, this is the most important, most wondrous map ever produced by humankind.
Claire Stinson: That was President Bill Clinton announcing the scientific breakthrough at a press conference that year.
President Bill Clinton: This is a great day, thank you very much.
Claire Stinson: But epidemiologists have actually been using genetic sequencing to identify the DNA of organisms that cause foodborne illness since the late 1970s.
So in 2023, when Josh Rounds and his colleagues are investigating the perpetrator behind this salmonella outbreak, their first move was to get its fingerprints. Its genetic profile.
Josh Rounds: We had all done whole genome sequencing in the different states. So that's where they're taking the isolate of that bacteria and they're sequencing it. And then there's a system for comparing that to the other cases that are happening within your state and also nationwide.
Claire Stinson: That system is PulseNet, an information sharing network run by CDC. It sounds like something out of a sci-fi movie, and it kind of is. One epidemiologist I spoke to compared PulseNet to that scene from Minority Report where Tom Cruise is sorting through all those screens of data trying to crack the case.
Josh Rounds: Really, anytime you hear about a commercially distributed food outbreak where there's multiple states involved, without PulseNet we wouldn't have been able to detect that outbreak.
And that's really the only way that we're able to say, ‘Oh, this salmonella case in Minnesota is genetically related to this salmonella case in Georgia.’ That was the first indication that there was something going on that we needed to investigate.
Claire Stinson: That's what that CDC email was about. PulseNet had revealed that the samples from cases in Minnesota, Ohio, Virginia and elsewhere were all genetically similar. They were what's called a cluster.
That meant Josh's wintertime salmonella case wasn't just a one-off or a localized thing. It was an outbreak, potentially affecting the whole country. And people in all these states were getting sick from the same food. Now it was up to state epidemiologists like Rounds to find out what product was making them sick and how much of it was still out there.
The next day, CDC convened a huge multi-state conference call with all members of the so-called relay race team.
Josh Rounds: There's a lot of different people that are involved in these investigations. Every state that has cases, our Department of Agriculture and then all of the regulatory agencies too.
Claire Stinson: There were a lot of acronyms.
Josh Rounds: So USDA, FSIS. CDC on the national side. It's a lot of people. During those calls, we'd talk about the exposures our cases are reporting and what steps we want to do next in the investigation.
Claire Stinson: Rounds filled the team in on what they'd learned from interviewing their Minnesota case.
Josh Rounds: That routine interview, they hadn't reported really anything that stood out. They had shopped at several different grocery stores, ate a lot of different foods, but they had shopped at a warehouse club store and mentioned eating prosciutto.
During one of those calls, another state reported that their case ate a charcuterie sampler that included prosciutto. And it happened to be from the same warehouse club chain that the Minnesota case reported. So I was like, ‘Oh, that's pretty interesting.’
Claire Stinson: To double check their hunch, the epidemiologists turned to another CDC resource, the FoodNet Population Survey.
Josh Rounds: FoodNet does a survey every once in a while. I think the last one was pre-pandemic, where they're asking people in the general population what foods you ate in the last seven days. In outbreak investigations, we want to compare what we're seeing with our cases in the cluster, the outbreak, to what is the background rate of that food consumption. And is that more than we would expect?
Claire Stinson: The FoodNet Survey showed that about 40% of Americans eat charcuterie meats in a normal week. Think pepperoni, salami, prosciutto, that kind of thing.
But by now, investigators had interviewed 68 people who had gotten sick with salmonella, and 50 of them had eaten charcuterie. That's 74%, much higher than the general population. That suggested that charcuterie might indeed be the culprit. Now, they just had to prove it.
Josh Rounds: So CDC quickly developed a supplemental questionnaire for the states to use where we could re-interview our cases to get some additional detail.
A couple of days later, we were able to get a hold of our case for that re-interview, and they reported that same brand of charcuterie meats as the case in another state. We have two cases reporting this exact same product. That seems unusual.
Claire Stinson: Can you hear the excitement in his voice?
Josh Rounds: In this case, we got lucky. It's happened to be a product that was sold as a twin pack. So they still had the remaining half of the package unopened at home and were willing to let us test it.
Claire Stinson: For Rounds, this is an aha moment. It's rare enough for someone to remember they ate prosciutto a week ago. To actually still have the product available to test? It was an amazing stroke of luck.
When the Minnesota lab did another round of whole genome sequencing on the charcuterie sampler, they found it did indeed have salmonella. And that salmonella was closely related to bacteria from sick people. That suggested that people got sick from eating that specific lot of that specific charcuterie sampler.
And specificity is really important here. The more precisely epidemiologists can pinpoint the source of an outbreak, the more effective all this detective work is. Pointing the finger at the wrong food item can cause economic damage for the companies whose products are recalled, and it doesn't do anything to keep people from getting sick.
Back in Virginia, Cindy was finally feeling better. The symptoms of her mystery illness had subsided, and she was back at home. That's when her phone rang.
Cindy Ligon: I got a phone call from a nurse with the Virginia Department of Health. And she explained that they had sent my samples off and that it turned out that I had salmonella.
And she immediately started asking, ‘Where had I eaten? What had I done?’ And I started just racking my brain. And I had been to lunch at a new restaurant, and I convinced myself, ‘Oh my gosh, that's where I got it.’ And I was telling people, ‘Don't go there.’ In hindsight, I feel really bad that I spread that rumor because it wasn't true.
Claire Stinson: See by then, investigators knew Cindy had been sickened by a specific brand of charcuterie sold at a warehouse store.
Cindy Ligon: They took the fingerprint of my particular bacteria, and sure enough, it matched to that outbreak.
Claire Stinson: Cindy was skeptical: salmonella from charcuterie? She wasn't even eating meat at that time.
Cindy Ligon: And I'd been to a party where there had been some charcuterie boards out, and I didn't eat the meat. But I may have picked up an olive or a piece of cheese, something that just minusculely had the salmonella on it from the meat. And six days passed before anything happened.
Claire Stinson: Turns out the friend who hosted the party bought the very same brand of charcuterie from, you guessed it, the very same club store.
Cindy Ligon: She was in disbelief. It was an unopened package, and no one else had been sick. It just didn't seem plausible, but it was.
Claire Stinson: Regulators worked with the manufacturer to get the product taken off the shelves, just after New Year's Day 2024.
Reporter 1: If you have this in your refrigerator, check it out. Just throw it out. This morning, the CDC is expanding its warning about the risk of salmonella on charcuterie meat after more people got sick.
Claire Stinson: In total, 104 people in 33 states got sick that winter from that salmonella outbreak. No deaths were reported, but 27 people were hospitalized, including Cindy Ligon in Virginia.
It was the first big food recall of the year, but certainly not the last. In 2024, CDC identified 13 multi-state outbreaks of infections caused by E. coli, listeria, and salmonella. Those led to recalls of deli meat, organic carrots, cucumbers, even the onions that go on top of a popular fast food chain's burgers.
So we're all hearing about these recalls on the news. Does that mean our food supply is getting more dangerous? Josh Round says no.
Josh Rounds: It's not that the safety of food is getting worse, it's that we're getting better at detecting these outbreaks and solving them. So I would say way back when, you were really only detecting your local outbreaks and only really large outbreaks. As our systems have gotten better, we're able to detect outbreaks that are smaller numbers of cases and then also sooner.
Claire Stinson: Cindy Ligon is grateful the system is working.
Cindy Ligon: I was incredibly impressed with the level of care and the systems that were in place to obviously solve the mystery. Beginning with the hospital who made the report and sending off my samples and so forth. I didn't realize that was happening behind the scenes.
Claire Stinson: It's one of the key roles public health professionals play as part of their work to protect everyone and every community across the nation. For her part, Cindy isn't taking any chances.
Cindy Ligon: I just didn't understand how vulnerable we were. Now, I won't eat foods that are past their expiration date. I sniff on my ... I wash vegetables and fruits, but things like a cantaloupe. If I were going to cut a cantaloupe, it never occurred to me that I should wash the outside of that cantaloupe. I do now. I'm very paranoid about what I put in my mouth because that was the sickest I've ever been. I don't want to repeat that.
Claire Stinson: In Minnesota, Josh Rounds is back at work. Another day, another foodborne illness to investigate. Another relay race to run.
Josh Rounds: It's really a team sport. I think it takes a lot of work by a lot of different people. People who are drawn to public health are not necessarily people that want to be out there in the public. We really would like to be preventing problems as much as we can, and we're happy to be in the background doing the work that we're doing.
But that being said, know when you do see that your work led to this recall, and hopefully you're preventing a lot of people from getting sick. That does feel good.
Claire Stinson: Thanks to Cindy Ligon, Josh Rounds and the good folks at the Minnesota Department of Public Health for talking with us for this episode. I'm your host, Claire Stinson.
Maya Kroth was the show's producer. And thanks for listening to Contagious Conversations produced by the CDC Foundation and available wherever you get your podcasts.
Be sure to visit cdcfoundation.org/conversations for a transcript of today's show and an archive of all of our previous episodes.
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