Cyclosporiasis symptoms, testing and treatment: a primary care guide

A cyclosporiasis outbreak tied to contaminated iceberg lettuce has sickened 6,348 people across 15 states, with Michigan recording more cases than anywhere else in the country, according to the Centers for Disease Control and Prevention (CDC).

The numbers have reached two deaths and 517 hospitalizations. Cases associated with the contaminated lettuce outbreak are counted among at least 10,468 laboratory-confirmed cases in 47 states as of Aug. 3, according to the latest CDC figures.

For primary care physicians, the outbreak raises a practical problem: Cyclosporiasis is easy to miss because standard stool tests do not reliably catch it and symptoms overlap with more common summer gastrointestinal (GI) illnesses.

Molly O’Shea, M.D., has run an independent primary care pediatric practice in the Detroit area for more than 30 years and has treated patients through the current surge. She spoke with Medical Economics about how to recognize cyclosporiasis in the exam room, which tests to order, how to treat confirmed cases, and how to talk with worried patients. This transcript has been edited for length and clarity.

Medical Economics: What is cyclospora, and how do people get it?

Molly O’Shea, M.D.: It’s a parasitic infection that occurs in people of all ages. It doesn’t discriminate. It’s commonly caused by eating fresh vegetables or fruit contaminated with the parasite or its eggs. It’s not spread from person to person; it’s contracted by eating the contaminated food, and then the parasite goes into our intestinal tract and replicates there. We pass it in our stool, it gets into the water supply or the sanitation system, and it may then take hold somewhere else. It’s thought to get onto fruits and vegetables through irrigation systems or through the equipment used to process them. I’m in Michigan, so we’re ground zero for this outbreak. We have more cases than any other state, so we’re definitely familiar with the symptoms it presents.

Related coverage: Cyclosporiasis outbreak: 13 things primary care physicians need to know right now

Medical Economics: Should people avoid fresh fruits and vegetables until the outbreak passes?

Molly O’Shea, M.D.: There might be lots of reasons to put a lockdown on certain foods, but I don’t think that has to be one of them. I think a lot of people have sworn off fruits and vegetables right now because of this risk, but there are things we can do to make our produce safer to eat, and we can still enjoy the abundance of fresh produce that’s available in the summer harvest. If you bring fruits and vegetables home, there are things you can do in how you wash and prepare them that can dramatically reduce your risk. If you have lettuce or other leafy vegetables, take the outer leaves off and throw them away, then wash the rest well for a minute or more, actually rubbing it. Do the same for fruit that has a peel you don’t remove before eating. Some produce, like raspberries or leafy herbs such as cilantro, have tiny hairs that can hold onto the parasite and make it harder to wash off. For those, there may be some benefit to a one-part vinegar, three-part water solution: Agitate the produce in that, then rinse it off. Cooking any fruit or vegetable to about 157 degrees will also kill the parasite and its eggs, though I realize most people aren’t measuring that. I don’t think we need to give up all the good things summer produce offers. There are ways to still enjoy it safely.

Medical Economics: Does buying local produce make it safer?

Molly O’Shea, M.D.: I think that’s true to a point. Buying local is great for a lot of reasons: the food will have been on the vine longer and grown to a riper point before it’s picked and brought to market, so you’re getting more of the nutrients. You’re also supporting people in your own community. But depending on what “local” means, you still may not know what that farm’s irrigation system looks like, or exactly how that produce was prepared and handled on its way to market. So I think there’s a little more due diligence involved than just assuming that because it’s local, it’s automatically safer.

Medical Economics: For physicians who haven’t seen a case before, what does cyclosporiasis look like in the office, and how do you distinguish it from other illnesses that cause diarrhea?

Molly O’Shea, M.D.: It can be tricky, because like many other parasitic gastrointestinal illnesses, it causes bloating, explosive diarrhea and cramping. Giardia and other common summer parasites will do that too. Enteroviruses, which also cause GI distress in the summer, don’t cause as much explosive diarrhea and don’t tend to last as long. Cyclosporiasis will last about six weeks without treatment. We actually tell families not to bother coming in until three or four days into symptoms, because norovirus and other conditions that cause GI distress are often relatively short-lived; people tend to improve quickly on their own. So rather than have everybody come in on day one of diarrhea, we say: Come in on day three or four. If your symptoms are starting to improve by then, that’s reassuring. But if you’re still having seven or eight bouts of explosive diarrhea a day at that point, we want to see you, and we’ll talk about testing. Either we’ll run three O&P (ova and parasite) tests, three days apart, using a stain that specifically looks for the Cyclospora parasite, since a standard O&P test won’t catch it, or we’ll run a PCR (polymerase chain reaction) test looking for it specifically.

Medical Economics: There’s a claim online that Cyclospora isn’t caught on routine stool testing. What do you want physicians to know about that?

Molly O’Shea, M.D.: That’s actually right. You have to talk to your lab, because each one may handle O&P testing differently, and Cyclospora requires a special stain to detect. It won’t be looked for unless it’s specifically requested in most lab settings. In our practice, our lab sends different containers depending on what we’re ordering: a traditional O&P, a Cyclospora-specific O&P, or, if we’re doing three tests over three days, a PCR that looks only for Cyclospora.

Medical Economics: The incubation period can run up to two weeks. How should physicians approach taking a patient’s history, given that people may not remember what they ate that far back?

Molly O’Shea, M.D.: That makes it hard, and it’s what makes it so difficult for the epidemiologists who have to do the detective work of figuring out where an outbreak started. I’m glad that’s not my job. I just have to decide whether to run the test, because frankly, every parent is already wondering where their child got a cold or a rash, let alone where they got Cyclospora. When the incubation period could be anywhere from a week to two weeks out, and there’s a wide variety of foods and locations to consider, it gets complicated fast. It also takes a fairly high dose of the parasite to become infected, which is why only one person in a family might get sick even though everyone ate the same things. You might not get infected if you ate a few raspberries with the parasite on them, but if you ate an entire pint, you might be in trouble. Some people believe that if more than one person in a family gets sick, it spread from one person to another, but we understand that it doesn’t. There’s a lot of misunderstanding in the community about this. I tell parents: don’t play the “where did I get it” game. It’s not worth your time. Instead, play the “how do I get rid of it” game, and let’s manage what we have.

Medical Economics: This can be treated with a relatively inexpensive antibiotic. What’s the standard treatment regimen?

Molly O’Shea, M.D.: Once you have a positive test, either PCR or a Cyclospora-specific O&P, it’s a simple treatment: Bactrim, which is sulfamethoxazole-trimethoprim. You take it for about a week, and that’s usually enough to do the job. If someone has had symptoms for a long time, they might need a somewhat longer course. There’s some debate about whether people who’ve been symptomatic for a long time can have false negative results, because the parasite sheds in smaller amounts over time even though the intestines are still inflamed and irritated from having harbored it. So the question becomes: when do you decide to treat based on symptoms alone, given a long duration of illness? That’s an individualized decision in each clinical setting. But it is simple to treat, assuming you don’t have a sulfa allergy. I haven’t yet had a patient with a Bactrim or sulfa allergy that I’ve had to treat, so I’d have to look up the alternative.

Medical Economics: Is hospitalization or a specialist referral common?

Molly O’Shea, M.D.: I think we’re underestimating how many cases are actually happening in the community. We’re underdiagnosing it, because some people have milder symptoms or their primary care provider isn’t considering Cyclospora as the cause. Even though Michigan’s numbers are unusually high for us, I still think we’re undercounting what’s actually out there. That said, yes, there are hospitalizations, and the people getting hospitalized tend to be quite sick, often with underlying health issues that make them more susceptible to severe illness generally. You do have to be concerned about dehydration and other complications, especially in patients with underlying GI issues, kidney issues or cardiopulmonary issues, because that much diarrhea puts real stress on the whole system.

Medical Economics: There’s been some online discussion of ivermectin as a treatment. What should physicians tell patients who ask about it?

Molly O’Shea, M.D.: I think the best answer is that the highest-quality evidence we have shows Bactrim is by far the best treatment for cyclosporiasis, and that good washing of fruits and vegetables before eating or cooking them is the best prevention. Ivermectin as a strategy for reducing risk or as a treatment hasn’t been studied well enough to place it in either category.

Medical Economics: How should physicians handle patients who hear about an outbreak on the news and worry it’s happening to them, even when it’s unlikely?

Molly O’Shea, M.D.: One of the joys and opportunities of primary care is the relationship we build with the families we serve. If we’ve had the chance to do that, families look to us not to just order a test, but to answer their questions and give them guidance. When they hear something alarming on the news and then develop a symptom that matches it, in my experience of more than 30 years, they’re very rarely looking for us to reflexively order a test. What they want is for us to listen, really hear what their symptoms and worries are, and empathize with that. Then, if it isn’t the right time for a certain test, we explain why, and we lay out a plan: here’s what we’ll do over the next two days, or the next three weeks, and here’s where that test fits into the plan. That reassurance, that I’m not dismissing you, that there’s a plan and a reason behind it, is what gives people a sense of calm. So when they’re worried on day one, they can feel comfortable waiting until day three. And if they still have diarrhea on day three, believe me, I want to run the test as much as they do. It’s a bit like reassuring a young child: I know you’re worried, but we’re not going to do this right now. If the problem is still there in an hour, we’ll deal with it then. Instead of tending to every anxiety the moment it appears, which usually makes it worse, we help them sit with it a little.