What we know about the cyclosporiasis outbreak linked to produce

Geoff Bennett:

Thirty-one states are now reporting cases of a parasitic intestinal disease that is making life miserable for those who contract it. And while the U.S. has seen outbreaks of cyclosporiasis in the past, the some 4,000 reported cases this summer are much higher than normal and raising real concerns about the illness.

William Brangham has more on what you need to know.

William Brangham:

Right now, officials can't pinpoint the exact source or sources of this outbreak. It's a food or waterborne disease caused by a parasite, cyclospora. And pinpointing precisely where it's coming from is a challenge.

Michigan is bearing the brunt with more than 2,600 reported cases, including 44 that have landed people in the hospital.

Joining us to explain what all this means and how to stay healthy is Dr. Omer Awan. He's at the University of Maryland School of Medicine.

Dr. Awan, thank you so much for being here.

To start off with, if I were to ingest this parasite, how do I know that I have got it? What are the symptoms people should look out for?

Dr. Omer Awan, University of Maryland School of Medicine: Well, the typical symptoms, William, are things like nausea, fatigue, bloating, and of course, explosive, watery diarrhea.

And that's the symptom that's been getting a lot of attention because this is really different, because most stomach bugs usually the watery diarrhea lasts about two or three days. With the cases of cyclosporiasis the diarrhea can last weeks, if not months. And that's what makes this so problematic.

And if you have diarrhea for more than perhaps two or three days, you should really talk to your doctor, get tested, and get treated so that you can feel better.

William Brangham:

And I understand that the incubation period for the for the parasites' eggs, once they're in your body, it can take days or even a week or more for you to start showing symptoms, which seems like it makes it very difficult to identify what thing it was that you ate or drank that caused the problem.

Dr. Omer Awan:

That's exactly right. The incubation period can be anywhere from two days to 14 days. So that's two weeks. So many of us don't really remember what we ate two weeks ago. I mean, I can't even remember what I ate two weeks ago, so it's very problematic.

And it makes it challenging to really know and track down what's causing these cases. And that's exactly why the CDC and the United States don't know exactly what the source is for all these thousands of cases, because we don't know exactly what food, what produce, or what brand is leading to all these cases that we're seeing here currently in the United States.

William Brangham:

I mean, as we have mentioned, this is not a new bug. We have seen outbreaks of this before, but this one seems particularly large. Do you have a sense as to why this one's so big?

Dr. Omer Awan:

Well, one of the reasons is exactly what we just stated, William, that we don't know what the source is. We don't know what the exact produce is or the brand of the produce.

Now, historically, most cases have been related to contaminated food from produce, things like lettuce, cilantro, basil, raspberries even. But we haven't pinned that down. And because we haven't pinned it down, that means that these cases are likely to disseminate. People are still eating the contaminated food that's leading to so many cases.

The other is the incubation period that we talked about. Because the incubation period can be two weeks, even if we were to stop and contain the source today, there would still be increased cases a week from now, two weeks from now, because of this incubation period.

And then, finally, what I would say is that this usually peaks in the summer. Cyclosporiasis usually thrives on heat and humidity. And we typically see a lot of cases from may to August, certainly not the magnitude that we're seeing currently, but we do see cases in these summer months.

William Brangham:

Some critics have pointed out that CDC last year stepped back from some of its foodborne sort of poison pathogen surveillance. Is that contributing to this problem at all or not?

Dr. Omer Awan:

I would say absolutely it is, William, for a couple of reasons.

One is remember that the HHS and the federal government laid off a lot of CDC employees. Many of them were the very employees that would track these particular outbreaks. And the other is that, from July of 2025 last year, the CDC has no longer required reporting cyclosporiasis. It's become optional to report this to the CDC's Foodborne Disease Active Surveillance Network.

So this is precisely why we don't have a good handle of exactly the number of cases. If you remember, the CDC has reported less than 1,000 cases, but we know that there are more than 3,000 or 4,000 cases. I mean, there are more than 2,006 hundred cases in Michigan alone.

So the states have more of an accurate representation than actually even the federal government, the CDC. So these two reasons are really the main reasons why our response outbreak has really been hampered for cyclosporiasis.

William Brangham:

You mentioned that people should go see their doctor if they have these symptoms. We should say this is not a fatal illness, and there is an antibiotic treatment for it. But what kinds of things should people do to try to protect themselves?

Dr. Omer Awan:

The good news is that there are treatments available. You typically take an antibiotic known as Bactrim for about seven to 10 days. Overwhelmingly, most people feel much better, their symptoms resolve with maybe a week treatment of antibiotics.

There's a lot of commonsense tactics that people can use. One, of course, is just washing your hands for 20 seconds, making sure that we wash produce with running water, making sure you really scrub that produce, refrigerating produce as soon as you get back from the grocery store.

But, ultimately, the only way you can really eliminate cyclosporiasis is by cooking it, cooking it at temperature of 158 degrees Fahrenheit. If you do that, you eliminate it. But just by doing those simple commonsense measures, you can significantly reduce your chances of getting cyclosporiasis.

William Brangham:

Dr. Omer Awan of the University of Maryland Medical School, thank you so much for being here.

Dr. Omer Awan:

My pleasure. Thanks, William.