Cyclosporiasis: Fact vs Fiction

Summary

Podcast Summary: Chasing Life with Dr. Sanjay Gupta

Episode: Cyclosporiasis: Fact vs. Fiction
Date: July 17, 2026
Guests: Dr. Jennifer McIntyre, founder of Food Safety Strategy
Host: Dr. Sanjay Gupta, CNN’s Chief Medical Correspondent

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Episode Overview

This episode explores the largest recorded outbreak of Cyclospora in the United States since 1990, with Michigan at the epicenter. Dr. Sanjay Gupta leads a deep dive into what Cyclospora is, why this outbreak is particularly puzzling, and how both experts and the public can respond. He’s joined by Dr. Jennifer McIntyre, a microbiologist specializing in food safety, to clarify misconceptions, discuss outbreak investigations, and offer practical advice on minimizing personal risk.

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Key Discussion Points and Insights

What is Cyclospora? (04:00–06:34)

• Definition & Uniqueness: Cyclospora is a single-celled parasite, more complex than common bacterial pathogens like E. Coli or Salmonella.
  • “As a parasite, what this means to me is that it requires a host in order to multiply, to replicate... For this organism, the only host is humans.” — Dr. Jennifer McIntyre (04:00)
• Transmission: Unlike bacteria, it cannot replicate outside the human body.
  • Not spread directly (i.e., not classic fecal-oral), but rather through contaminated food/water after a period outside the body.
  • Needs 1–2 weeks in the environment to become infectious.
  • “It’s not the case where somebody was sick, didn’t wash their hands, they prepared food... and they immediately get sick. It’s a slightly different mechanism here.” — Dr. McIntyre (05:16)

How Outbreaks Start and Spread (07:08–10:28)

• Contamination Source: Usually water tainted with raw sewage, possibly from symptomatic or asymptomatic carriers.
  • Outbreaks hypothesized to begin when contaminated water is used for irrigation or washing produce.
  • “We usually hypothesize there was water that was contaminated with raw sewage, including from somebody or maybe a few people who were carrying cyclospora.” — Dr. McIntyre (07:08)
• Incubation Challenge: Infection symptoms appear days to weeks after exposure, making tracing a challenge.
  • “That replication within the body seems to take between a couple of days up to a couple of weeks before the person shows symptoms...” — Dr. McIntyre (09:04)
• Comparisons to Other Pathogens: E. Coli and Salmonella typically incubate for 3–7 days; Listeria can take up to two months.

Magnitude of the Outbreak & Underreporting (10:55–12:08)

• Underreporting: Many cases go unreported due to embarrassment or mild symptoms.
  • “For every case that is confirmed that’s counted, there are probably 80 or so people who are not counted but did actually have the illness.” — Dr. McIntyre (11:01)
  • Implies potentially hundreds of thousands of real infections during large outbreaks.

Outbreak Investigation Complexities (12:10–15:16)

• Multiple Outbreaks, Not One: Evidence suggests this is not a single-source outbreak.
  • “In all likelihood, this is not one outbreak. This is multiple outbreaks.” — Dr. McIntyre (13:36)
• Difficulty with Genetic Testing: Cyclospora is much harder than bacteria to genetically type and trace.
  • “To do it accurately, to do it quickly, and to do it... cost effective is very different from the bacterial side.” — Dr. McIntyre (13:22)

Current Theories on the Michigan Outbreak (15:36–16:52)

• Potential Source(s): Michigan’s record-setting numbers hint at a large, centralized problem, possibly linked to leafy greens.
  • Health officials suspect lettuce or salad greens.
  • “There must be something very large that’s going on. And my hope is that… enables a more rapid identification and resolution of the issue.” — Dr. McIntyre (15:47)
• System Failure: Outbreaks should not happen—failure occurred somewhere in the supply chain.

How to Protect Yourself (19:05–23:11)

• Produce Risk: Unclear which fresh produce is most risky; Cyclospora can contaminate a broad range.
  • Items implicated in past outbreaks: cilantro, basil, leafy greens, raspberries, berries.
• Washing Guidance:
  • “The recommendations from FDA, CDC and others is always to wash your produce well under running water.” — Dr. McIntyre (20:11)
  • Washing helps but doesn’t guarantee safety. If a recall is issued, do not attempt to salvage by washing.
  • “If a type of food is identified as causing illness and there’s a recall… people shouldn’t think… let me just wash it thoroughly. That would be very, very bad behavior.” — Dr. McIntyre (20:46)
  • Commercial produce washes, vinegar, and baking soda are not more effective than water.
  • Freezing or refrigeration does not reliably kill Cyclospora.
  • “For this one, the very first outbreak... was associated with raspberries that had been frozen, really.” — Dr. McIntyre (22:34)
• Cross-contamination: Risk exists, especially via kitchen utensils and surfaces, though Cyclospora cannot multiply outside a host.

Waterborne Risks (24:01–26:05)

• Swimming Risks: Chlorine is less effective against Cyclospora than against bacteria.
  • “Chlorine, as best we can tell, doesn’t have as much of an impact on Cyclospora...” — Dr. McIntyre (24:16)
• Advice for Hotspot Regions: Avoid swimming in lakes/rivers in affected areas; monitor public health advisories.
  • “Sounds like probably not a good idea right now.” — Podcast Host (25:47)

Seasonality & Factors Behind Outbreaks (26:07–27:33)

• Cyclospora Season: Late spring and summer (June-July) are typical peak months; numbers taper off by August.
  • “This is considered cyclospora season. It’s a pretty predictable pattern year over year.” — Dr. McIntyre (26:14)
• Unknowns Persist: The precise cause of the seasonal trend and what makes the parasite become infectious remains unclear.

Foodborne Disease Surveillance Failures (27:33–29:01)

• Recent Cuts to Monitoring: CDC’s FoodNet system no longer tracks Cyclospora, making data scarce and hindering future outbreak investigations.
  • “It is really disturbing to me that we just won’t have the data. And without those measurement tools, without visibility, I think it’ll be much more difficult to reflect on these outbreaks...” — Dr. McIntyre (28:32)

Final Advice for Listeners (29:01–30:15)

• Stay Informed: Follow news, heed official recall and health advisories, and adjust behaviors if you are in a hotspot.
  • “I think follow the news, make sure that as public health investigators figure this out… you are well aware of any advisories, any recommendations, any recall notices that are coming out.” — Dr. McIntyre (29:30)
• Keep Eating Produce: Unless living in a high-risk zone, don’t let fear drive you to abandon healthy fruits and veggies.
  • “For many of us… we shouldn’t be overly anxious in changing our behavior, avoiding foods that are very healthy for us.” — Dr. McIntyre (29:58)

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Notable Quotes & Memorable Moments

• Cyclospora’s Unusual Nature:
  • “It’s a people problem. Humans are the only host… a blessing and a curse.” — Dr. McIntyre (04:00)
• Challenges in Stopping Outbreaks:
  • “These are complicated. They are sort of these Sherlock Holmes level investigations.” — Sanjay Gupta (01:43)
• On the scale of under-diagnosis:
  • “For every case that is confirmed... there are probably 80... who are not counted.” — Dr. McIntyre (11:01)
• Don’t Wash Recalled Produce:
  • “That would be very, very bad behavior. If there’s contamination, it is very difficult to confidently say, I have removed all contamination.” — Dr. McIntyre (20:46)
• On Surveillance Losses:
  • “It is really disturbing to me that we just won’t have the data... much more difficult to reflect on these outbreaks...” — Dr. McIntyre (28:22)

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Memorable Timestamps

• 04:00 — Dr. McIntyre explains Cyclospora’s life cycle and unique human-only infection route.
• 11:01 — Discussion on the CDC’s estimate: an 80-to-1 ratio of real-to-confirmed cases.
• 13:36 — Explanation that the current surge is likely several outbreaks, not one.
• 15:47 — Details on Michigan and clues about possible sources (lettuce/salad greens).
• 20:11 — Best practices for washing produce and limits of effectiveness.
• 24:16 — Swimming and chlorinated water safety concerns.
• 26:14 — Why summer is “cyclospora season.”
• 28:32 — Impact of CDC cuts to foodborne pathogen surveillance.
• 29:30 — Dr. McIntyre’s final recommendations to listeners.

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Episode Takeaways

• Cyclospora is a resilient, human-only parasite with a puzzling transmission cycle and a peak in summer.
• Outbreak investigations are hampered by long incubation, underreporting, and detection difficulties.
• Standard washing and food safety practices help but can't ensure safety if a product is contaminated; recalls should be strictly followed.
• Foodborne disease surveillance in the US has been cut back, making future outbreaks harder to analyze and prevent.
• Stay informed, follow public health updates, and continue enjoying healthy produce unless living in a known outbreak zone.

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This summary captures the richness and nuance of the discussion, offering a clear and useful guide for listeners and non-listeners alike.

Transcript

[Sanjay Gupta]

Welcome to Chasing Life. You have no doubt heard of E. Coli and salmonella, but this summer there is another name that's showing up in the headlines and that is Cyclospora. I gotta tell you, I've covered a lot of outbreaks over the last quarter century, but this one has been a little baffling. We know first of all that this is a tiny parasite linked to contaminated produce and certain water sources that can cause weeks of diarrhea, cramping and frankly, other miserable symptoms. Also know that thousands of people are already sick across the country and that the numbers are rising. As of this recording, the hardest hit state is my home state of Michigan. Ohio a distant second. The numbers are going to still need to be confirmed by the cdc, but just the counts of those two states put it on track now to be the largest recorded outbreak of Cyclospora in the United States since 1990. And I think the most vexing part of this is that we really don't have a handle on why there's been this mass spike in cases. Government and state agencies have not been able to definitively point to a single source or to a particular culprit, although they are starting to zero in. That is the confusing part. At this moment, it's not even clear if this is just one big outbreak or if it's a number of smaller, unrelated outbreaks. So on today's show, we're going to talk to Dr. Jennifer McIntyre. She's a microbiologist and also founder of Food Safety Strategy, which consults with food companies about how to deal with food safety, including cyclospora. We will talk about why it's so

[Podcast Host/Interviewer]

important to pinpoint the source of this outbreak.

[Sanjay Gupta]

And again, I could tell you after covering outbreaks for the last 25 years, these are complicated. They are sort of these Sherlock Holmes level investigations. So we're going to talk about how these investigations start and hopefully how they ultimately solve the mystery. Also, perhaps most importantly, we'll tell you what you can realistically do to protect yourself beyond the standard guidance to wash your fruits and vegg.

[Unidentified Speaker]

Dr.

[Sanjay Gupta]

I'm Dr. Sanjay Gupta, CNN's chief medical correspondent. And this is chasing life.

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[Podcast Host/Interviewer]

So how I how's your life been recently?

[Dr. Jennifer McIntyre]

It's been a little crazy, but such is the life of a food safety professional, right?

[Sanjay Gupta]

So how do you, how do you

[Podcast Host/Interviewer]

first find out about something like this? What's the first call you get?

[Dr. Jennifer McIntyre]

You hear some industry rumors, you hear that something is going on. But also for this particular organism, for Cyclospora, it is seasonal and so it's in some ways kind of expected, unfortunately.

[Podcast Host/Interviewer]

So when you get a call like this, you're not that surprised, it sounds

[Dr. Jennifer McIntyre]

like, at least not initially, when it's June, July. No, not, not that surprised.

[Sanjay Gupta]

So let's get to some basics.

[Podcast Host/Interviewer]

First of all, what is cyclospora?

[Dr. Jennifer McIntyre]

So cyclospora is a single celled parasite. And me being trained as a, as a food microbiologist, that means a certain thing to me. Compared to bacteria or other types of organisms much more complex than the E. Coli or the Salmonella that we may hear about a bit more often. As a parasite, what this means to me is that it requires a host in order to multiply, to replicate. This is different than the bacteria that don't require hosts and the needing to have a host. For this organism, the only host is humans. It's people. So animals that we hear about sometimes associated with outbreaks, cows or chickens or birds flying overhead, they're really not involved in situations like this. This really is a people problem. So humans are the only host. And the fact that the organism requires a host is a blessing and a curse.

[Sanjay Gupta]

So if humans are required for this

[Podcast Host/Interviewer]

parasite to replicate, reproduce, how do they, like, where does it come from in the first place, then?

[Sanjay Gupta]

It's not in animals, you're saying requires humans. So how does this cycle begin?

[Dr. Jennifer McIntyre]

How it began in the first place? We simply don't know. It's kind of like what's the origin of life? How do you trace it back. But at some point this organism evolved, became what we now know as Cyclospora chiotenensis with a human host. And it just cycles through people. So it's people ingest it. And really what we're saying they're ingesting is a cyclospora that came from somebody else, from their feces, from another human. From another human. But it's not a direct fecal oral contamination, which we see with things like neurovirus or hepatitis A or even E. Coli or salmonella. This organism is very peculiar in that it needs, it seems it needs a week or two outside of the host. So say after somebody has defecated, takes a little bit of time before it becomes infectious and can make another person sick. And so while we always advocate for hand washing here, it's not the case where somebody was sick, they didn't wash their hands, they prepared food for someone else and they immediately get sick. It's a slightly different mechanism here and it creates a lot of challenges in outbreak investigations.

[Podcast Host/Interviewer]

So that's really interesting. And obviously you can start to imagine how that transmission occurs. But it's human to human, but not directly human to human. It's not what we refer to as fecal oral. Like somebody's hands are contaminated, they touch something or they get it in their mouth. You're saying that probably another human infected the food or the water in some way and that subsequently was the source of infection.

[Dr. Jennifer McIntyre]

That's exactly right.

[Podcast Host/Interviewer]

Paint a picture for me then.

[Sanjay Gupta]

What would be a likely start to

[Podcast Host/Interviewer]

an outbreak like this?

[Dr. Jennifer McIntyre]

If we look at outbreaks that have happened in the past, we usually hypothesize that there was water that was contaminated with raw sewage, including from somebody or maybe a few people who were carrying cyclospora. And we're not really sure if people are able to carry it and not show symptoms. So we have to keep that within the realm of possibility, these asymptomatic, symptomatic carriers. But certainly when people are sick, they're shedding cyclospora and we see it's referred to as explosive diarrhea. So there's a lot of feces, then that may have these oocysts, the cyclospora, in them. And if that gets into water systems and that water is then used for irrigation, for even washing equipment, if that water is in a lake, these are different ways that people may become exposed in a large scale.

[Podcast Host/Interviewer]

The cyclospore does need humans to replicate, as you, as you said. So it's shed through diarrhea, through fecal matter, gets into the water supply, the

[Sanjay Gupta]

parasite can still survive until it gets into another human.

[Dr. Jennifer McIntyre]

It seems to be pretty hardy. It does go through the sporulation process when it's outside of the host, transitioning from the not infectious form into an infectious form. And scientists aren't really sure of why or how exactly that happens, how long it takes, how long it persists in each state, the infectious and not infectious state. There's a lot about this organism that we do not understand.

[Podcast Host/Interviewer]

It's really interesting. So it's hardy enough. It sporulates, it can eventually then infect another human being. It starts to reproduce, replicate itself within that human being's body. And the person gets sick.

[Dr. Jennifer McIntyre]

Yes. And that replication within the body seems to take between a couple of days up to a couple of weeks before the person shows symptoms of illness, which makes it very difficult then to figure out how were they exposed.

[Sanjay Gupta]

And also this up to two weeks

[Podcast Host/Interviewer]

before you might start to show symptoms.

[Sanjay Gupta]

Can you give some context, like, what

[Podcast Host/Interviewer]

is it for E. Coli or salmonella?

[Dr. Jennifer McIntyre]

So, of course, it always depends. But salmonella and E. Coli are generally shorter, so we're usually looking at that three to four days, maybe up to a week. There are some other foodborne illness pathogens that take even longer. So Listeria monocytogenes, an organism that's of great concern for pregnant women and the elderly, that one can take a month, even up to two months.

[Sanjay Gupta]

Wow, that's incredible. So, as you said, and I'm probably

[Podcast Host/Interviewer]

one of these people who think, I'm probably gonna focus on what I just

[Sanjay Gupta]

ate, what did I have for dinner? Are there pathogens that get you sick that quickly?

[Dr. Jennifer McIntyre]

Usually when you get sick that quickly, it's because there was a pathogen in the food that produced a toxin in the food, and your body reacts very quickly to that toxin that's been produced. When it's an actual infection that requires the organism to be alive, be in you, and to grow, it takes a little bit more time.

[Podcast Host/Interviewer]

Right.

[Sanjay Gupta]

So. But I think this is an important

[Podcast Host/Interviewer]

point for a lot of people. If it's an infection that's making you sick, it's probably not what you just ate. It's probably something that you've eaten days, maybe even weeks earlier. So this gets to the challenge of the investigation.

[Dr. Jennifer McIntyre]

Absolutely.

[Podcast Host/Interviewer]

Do you have any sense? So today's Tuesday. Every day there's new numbers that are coming out from the CDC in terms of how many people are confirmed to have the cyclospore infection.

[Sanjay Gupta]

Any Sense of how many people are

[Podcast Host/Interviewer]

probably actually infected that may not seek medical care or get sick enough to need it.

[Dr. Jennifer McIntyre]

That's a great question, because a lot of people don't seek medical care. And for this organism, because it's diarrhea and people may be embarrassed or they may think it's gonna go away, there are a lot of people who won't seek medical attention. And so CDC has provided some estimates for the variety of foodborne pathogens. So for each case that is confirmed, how many, for various reasons might not be confirmed, this one has one of those higher multipliers. And so the last CDC estimate that I saw was about 80. That for every case that is confirmed that's counted, there are probably 80 or so people who are not counted but did actually have the illness. Now with the media attention, I hope that people are more likely to seek medical attention, that maybe that multiplier is not counter. Not quite as high. But still, 80 is a lot.

[Podcast Host/Interviewer]

Yeah, I mean, if you think about just. I'm throwing around numbers right now, but

[Sanjay Gupta]

let's say 2,000 confirmed cases, you're talking

[Podcast Host/Interviewer]

hundreds of thousands of potential infections out there, the vast majority of which are undiagnosed.

[Dr. Jennifer McIntyre]

That's right.

[Sanjay Gupta]

You know, I did this story years

[Podcast Host/Interviewer]

ago about a spinach E. Coli outbreak, and it was so fascinating, Dr. In terms of how they actually conducted the investigation, it has many of the notes that we're hearing about with the Cyclospora infection, asking people about their eating, obviously trying to figure out what the

[Sanjay Gupta]

sources are, and they ultimately traced it

[Podcast Host/Interviewer]

back to a particular farm.

[Sanjay Gupta]

Is that sort of story that we're

[Podcast Host/Interviewer]

going to hear with Cyclospora, do you think?

[Dr. Jennifer McIntyre]

Yes and no. Yes, in that hopefully there will be some identification of a source, whether that is a farm, some other product, or some other place where this all began. But I think where this organism and the number of cases here is different is that in all likelihood, this is not one outbreak. This is multiple outbreaks. And so there may be multiple sources. There probably are multiple sources. And so trying to tease these outbreaks apart is exceptionally difficult.

[Podcast Host/Interviewer]

I think with the E. Coli they were able to do genetic testing.

[Sanjay Gupta]

Is that sort of testing happening here?

[Dr. Jennifer McIntyre]

It's not as easy to do for cyclospora. This technology, this scientific technique has been available on the bacterial side of things for many years. Bacteria are a lot simpler organisms. Their DNA, it's a lot easier to work with. Cyclospora is pretty complicated. And so to do it accurately, to do it quickly, and to do it in a reasonably cost effective way is very different from the bacterial side. So that's challenge number one. Challenge number two is that for the bacteria, because they do grow outside of a host, we can stick them in a test tube, come back the next day, we have millions or billions of them. If we think that cyclospora, through epidemiology and through tree spec, we think it's coming from a particular location and we try to find it there in the environment or in a food, it's very difficult to find enough to do the test to perform that genetic analysis, because once it's outside of a person, you can't get it to grow. You don't have a lot of the genetic material to work with.

[Sanjay Gupta]

So are they doing this sort of

[Podcast Host/Interviewer]

testing or is it just not worthwhile?

[Dr. Jennifer McIntyre]

They are cdc. It has really been the one to evolve the methodology in order to be able to do this. But this is not a standard test. The genetic testing for cyclospore is not something that your rank and file laboratory can do, whereas on the bacterial side, it's become much more common, much more accessible from a lab perspective. So there are a number of challenges that make it more difficult. When we see cases of cyclospora and are trying to determine is this one outbreak or are there many outbreaks and

[Podcast Host/Interviewer]

you believe it's many outbreaks?

[Dr. Jennifer McIntyre]

Absolutely. I feel very confident saying there are many things going on at the same time here. And that would hold with historical patterns. Where we see the summertime, June, July, a number of illnesses often attributed to a few different sources, or at least a few different suspects.

[Podcast Host/Interviewer]

Much of this seems to be concentrated in Michigan, in the upper Midwest. Does that make you feel like there might be at least one gigantic source here?

[Dr. Jennifer McIntyre]

Clearly something is going on in Michigan and the health officials came out with some signals just yesterday, Monday. I hope that they hone in quickly so they have pointed to lettuce or salad greens. But when you have so many cases of illness and Michigan, the number of cases really is, I believe, record setting. Unfortunately, there must be something very large that's going on. And my hope is that that magnitude enables a more rapid identification and resolution of the issue.

[Sanjay Gupta]

Was there a failure here?

[Podcast Host/Interviewer]

Did something go wrong in order for this outbreak to happen?

[Dr. Jennifer McIntyre]

I have to say yes, there have to be failures because somehow this organism entered the system. Whether it was food or a water system that was used to produce food or a water system that people were exposed to, we should not be consuming this organism.

[Sanjay Gupta]

All right, we're going to take a quick break here, but when we get back, whether you should be washing your produce with something other than water to try and protect yourself from this parasite.

[Podcast Host/Interviewer]

Stay with us.

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[Podcast Host/Interviewer]

I've seen some of these questionnaires now, some of the ones that are going around in Michigan. And again, these are complicated and I think we're painting a picture for the audience. You're talking about maybe what you ate up to two weeks earlier. I mean, it goes without saying that most people are probably not going to

[Sanjay Gupta]

remember, but they did have a list

[Podcast Host/Interviewer]

of restaurants on there.

[Sanjay Gupta]

Is that the most likely source or is it vegetables that you may have

[Podcast Host/Interviewer]

bought in a grocery store?

[Dr. Jennifer McIntyre]

It's hard to say. A lot of times the restaurants are implicated because people do remember that they ate at a restaurant. And so when a certain brand, a certain chain shows up, it becomes a little easier for investigators to kind of hone in on it and see, especially when people are not related to each other, ate independently at a certain location, it makes for a good opportunity for public health for those investigators to gather more information. It's a little more difficult when we look at a grocery store because of the variety of items in a grocery store and the fact that many grocery stores are even different chains are carrying kind of similar items, it's just a little more difficult to tease those apart.

[Podcast Host/Interviewer]

People still want to eat their veggies.

[Sanjay Gupta]

Are there higher risk and lower risk veggies?

[Dr. Jennifer McIntyre]

It's a little too soon to tell. When you look at the list of items that have been implicated. Again, it's primarily an epidemiological linkage where people report eating and combining that with a trace back to see that there's a common source. But the list is pretty varied as I look at it. So we have herbs like cilantro and basil. We have leafy greens. We have some fruits like berries. Raspberries is one of the first outbreaks that was identified. So it's really, surprisingly, across the board. And if we think of something like water being a vehicle, then that could be associated with pretty much anything.

[Podcast Host/Interviewer]

I guess what I was driving at is that you're told obviously that eating produce is important. You should eat your fruits and veggies, but also to wash them really well.

[Sanjay Gupta]

And I'm curious, from a food safety

[Podcast Host/Interviewer]

standpoint, this is your area of expertise. What does washing them really well mean?

[Dr. Jennifer McIntyre]

The recommendations from fda, CDC and others is always to wash your produce well under running water. So not just in a container where it's just kind of soaking in itself, but running water, rubbing the surface, peeling things that can be peeled, removing outer layers for things that have outer layers. But I think people need to recognize, and we as food safety professionals shouldn't mislead people into thinking that they can bring that risk down to zero if that product has been contaminated. And especially if it's hopefully in the coming days, if a type of food is identified as causing illness and there's a recall, people should recall it. People shouldn't think, well, I have a product that's been recalled, let me just wash it thoroughly. That would be very, very bad behavior. If there's contamination, it is very difficult to confidently say, I have removed all contamination. And so, yes, washing helps. Removing outer leaves or peeling may help, but risk is never zero. And so if people are concerned, they should talk to their healthcare providers to understand their risk, their circumstances, and make an informed decision.

[Podcast Host/Interviewer]

Just going back to the washing, though, I mean, wash under running water. And I don't mean to get overly reductionist about this, but okay, wash under running water. What about using things like vinegar or baking soda or anything else like that?

[Dr. Jennifer McIntyre]

I know a lot of people look at whether it's the home vinegar, baking soda, or some produce washes that you can purchase at the store, and they don't seem to be any more effective. The vinegar being acidic, this organism may not care that much. We know that for items that are commercially washed that the sanitizers that are used in commercial wash systems are really not very effective against Cyclospora, although they are effective against E. Coli, Salmonella and others. But this organism's a bit different.

[Podcast Host/Interviewer]

What about freezing your produce or even in the refrigerator?

[Sanjay Gupta]

Does the parasite seem to survive that?

[Dr. Jennifer McIntyre]

It appears the parasite does survive refrigeration and, and it may survive freezing. So for many parasites, they don't freeze. Thaw cycles are used to destroy parasites in general, but for this one, the very first outbreak that I'm aware of was associated with raspberries that had been frozen, really. And so it makes me a little bit concerned that we don't want to be overconfident about the impact that freezing might have in reducing the viability, the livelihood of this parasite.

[Podcast Host/Interviewer]

If I cut into produce that has this parasite Cyclospora in it, could I then risk contaminating other foods in my kitchen?

[Dr. Jennifer McIntyre]

So the risk of cross contamination is always there. It would depend on the number of cyclospora. And this one doesn't grow outside the host. So for other types of products, if you cut something, you cut something else, you leave it on the counter. Even if you put it in the fridge, there might be increases in numbers. And we know that those Cyclospora that exist at the beginning are the same that are going to exist at the end, whether it's on your knife, on another food item. But there is the potential to cross contaminate. It's not something that's been extensively studied. To the best of my knowledge, we've

[Podcast Host/Interviewer]

talked a lot about food. But this can also spread through water and even in bodies of water that you might be swimming in. It's hot outside. A lot of people are in bodies of water, including lakes, I imagine chlorinated pools, for example. That's not going to be a problem.

[Dr. Jennifer McIntyre]

So chlorine, as best we can tell, doesn't have as much of an impact on Cyclospora as we hope on the bacteria.

[Podcast Host/Interviewer]

It's a hardy parasite.

[Dr. Jennifer McIntyre]

Yes, it is a very hardy parasite and there's a lot that we just, just don't know.

[Sanjay Gupta]

Say it can survive a chlorinated pool.

[Dr. Jennifer McIntyre]

It may be able to survive a chlorinated pool.

[Podcast Host/Interviewer]

Okay, what about lakes then? Obviously they don't have chlorine in them. Would you jump in a lake right now?

[Dr. Jennifer McIntyre]

A lake in my area, I would not hesitate to jump in a lake because I know that in this area where I live in Maryland, that the case counts aren't particularly high. And I would also think that if a lake was contaminated that a lot more people would already be sick. If the lake had a sign on it, though, that, you know, don't swim in this lake, they're high, E Coli counts, then I would certainly respect that and adhere to that.

[Podcast Host/Interviewer]

Yeah, pay attention to those warnings, for sure. I think that's a good message. But look, I'm from Michigan, that's my home state. I got a lot of friends up there. It's hot up there as well. Should they not be jumping in the lakes?

[Dr. Jennifer McIntyre]

That's Something where I do think it's worth looking at the region, the county that you're in. The state of Michigan has done a pretty good job reporting the number of cases by area, by county. And so I think you look and see are you in a hot spot and what precautions do your local officials advise?

[Podcast Host/Interviewer]

Sounds like probably not a good idea right now.

[Lindsay Sievert]

I may not.

[Sanjay Gupta]

I mean, I'm just, I'm just trying

[Podcast Host/Interviewer]

to be, you know, I got kids, I got elderly parents, you know, obviously I worry about myself.

[Sanjay Gupta]

Doesn't sound like it'd be a great

[Podcast Host/Interviewer]

idea to be jumping in a lake in the midst of a cyclospora outbreak.

[Dr. Jennifer McIntyre]

Probably not.

[Podcast Host/Interviewer]

Okay, why, why is this happening now? And if you look at previous outbreaks,

[Sanjay Gupta]

is it typically this time of year?

[Dr. Jennifer McIntyre]

It is absolutely this time of year. This, this is considered cyclospora season. So it's a pretty predictable pattern year over year. Come June, July, that's when we're seeing higher numbers. By August, they're really starting to taper off. And as we head into the fall, other than those travel associated cases, when we're looking at domestically acquired cases, they really go down and we don't really understand why.

[Podcast Host/Interviewer]

I mean, because you're presumably, if it's produce and it's contaminated irrigation, that's presumably happening year round.

[Dr. Jennifer McIntyre]

Why the organism becomes infectious may be a factor in the seasonality, but what triggers that infectivity, we simply don't know. And so it's quite possible that the parasite is around us all the time and it's just not making us sick.

[Podcast Host/Interviewer]

Yeah, I mean, we don't do screening tests for this sort of thing, so we wouldn't possibly know. And not only do we not do screening tests, as you point out, there's maybe an 80 to 1 ratio in terms of people who are carrying the cyclospora are infected versus people who are actually confirmed. So there's a lot of unknowns. It sounds like when it comes to

[Dr. Jennifer McIntyre]

cyclospora, a lot of unknowns.

[Podcast Host/Interviewer]

How are we doing, do you think, as a country in terms of surveillance? There's been a lot to be made of some of the changes to foodborne surveillance over the last couple of years.

[Sanjay Gupta]

What kind of are we seeing an impact of that with this outbreak when

[Dr. Jennifer McIntyre]

you see numbers this high? I'm not sure that we can attribute it to surveillance, although I am very concerned as we look toward the future, that it's just really difficult now to get data to look for trends and patterns. And so this, this organism Used to be one that I could go to a part of CDC's website and I could pull historical data. It was called Foodnet. It's an active surveillance system. But starting about a year ago, cyclospora as well as a number of other foodborne pathogens were removed from that list. It went from eight to two, cyclospora being one of the six that was cut. And so it is really disturbing to me that we just won't have the data. And without those measurement tools, without visibility, I think it'll be much more difficult to reflect on these outbreaks that have happened and be able to predict and hopefully act upon those outbreaks that might be in the future so that we can stop them or at least limit the impact.

[Podcast Host/Interviewer]

We've established today that there could be maybe 100, 200,000 people who may be infected right now. Just if you look at the number of confirmed cases and you say there's an 80 to 1 sort of likelihood of more people being infected. So for every one infection, 80 others potentially infected. What is your recommendation then for people who are listening?

[Sanjay Gupta]

Should they be doing anything different in

[Podcast Host/Interviewer]

their lives as a result of what's unfolding?

[Dr. Jennifer McIntyre]

I think follow the news, make sure that as public health investigators figure this out, and I'm reasonably confident, especially with these numbers, that they will, that you are well aware of any advisories, any recommendations, any recall notices that are coming out. Until that happens, I think it's assessing where you live. Are you living in a hotspot? Should you take any special precautions? But for many of us throughout the United States, we're not in hot spots. And I think we shouldn't be overly anxious in changing our behavior, avoiding foods that really are very healthy for us.

[Podcast Host/Interviewer]

Okay, Doctor, thank you for your time.

[Sanjay Gupta]

Really appreciate it.

[Dr. Jennifer McIntyre]

Thank you so much.

[Sanjay Gupta]

That was great.

[Podcast Host/Interviewer]

I learned a lot.

[Dr. Jennifer McIntyre]

It's pretty fascinating.

[Sanjay Gupta]

And that was my conversation with microbiologist Dr. Jennifer McIntyre, founder of Food Safety Strategy. Look, I hope this helped you through

[Podcast Host/Interviewer]

some of the confusion around cyclospora and

[Sanjay Gupta]

gave you a better understanding of just how to protect yourself and why these outbreaks can be so challenging to track in the first place. Thanks so much for listening. See you next week.

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[Lindsay Sievert]

What if doctors could detect Alzheimer's before symptoms appear, use artificial intelligence to improve diagnoses, or make surgery safer and more precise in real time? On the new season of Tomorrow's Cure, the chart topping and 2025Ambie Award finalist podcast from Mayo Clinic, we explore how breakthroughs like these are already transforming the future of healthcare. I'm Lindsay Sievert, the new host of Tomorrow's Cure. In this season, I'm joined by leading physicians, researchers and Mayo Clinic experts discussing the ideas and technologies reshaping medicine. You'll hear how retinal imaging and AI could help doctors detect Alzheimer's disease earlier. We also dive into the growing excitement around carbon ion therapy, one of the most closely watched advances in cancer treatment. And we explore how fluorescence guided surgery is helping doctors better visualize tumors, nerves and blood flow during procedures. So whether you're a patient, healthcare professional, or simply curious about where medicine is headed, Tomorrow's Cure invites you to imagine what healthcare could look like and shows you the future is already here. Follow Tomorrow's Cure on Apple Podcasts, Spotify or your favorite podcast, Apple.