Having diarrhea is already a miserable experience, but it might be even worse if it’s caused by the parasite cyclospora, which is transmitted by feces-contaminated food and water, and is causing upset stomachs throughout the nation.
As of July 14, the Centers for Disease Control and Prevention said it has confirmed 1,645 people have gotten ill by cyclosporiasis, the sickness cyclospora causes, and it is investigating an additional 5,100 suspected cases. The main symptom is “explosive” watery diarrhea.
Many of us are unfortunately familiar with what a foodborne illness feels like. What makes cyclosporiasis hard to diagnose is that it has a longer incubation period, and there is not yet a clear culprit on exactly which food is causing this outbreak. On Tuesday, Michigan health officials said lettuce was a possible cause; previous U.S. outbreaks have been linked to cilantro, basil, snowpeas, mesclun lettuce and raspberries.
What also makes this hard to diagnose is that not everyone who gets cyclosporiasis will have noticeable symptoms.
“Cyclosporiasis can go from being almost asymptomatic to lasting for a month and being pretty severe,” said Dana Mordue, associate professor of pathology, microbiology and immunology at New York Medical College.
If you do feel unwell, there are a few telltale signs that your watery bowel movement or upset stomach could be caused by this parasitic outbreak, according to health experts.

1. Consider how long you have had diarrhea.
If your diarrhea symptoms don’t resolve on their own, this is a worrisome sign that could point to cyclosporiasis. Having a foodborne illness caused by salmonella or norovirus can be unpleasant, but it is usually a short-lived nightmare for most people.
“Most foodborne illnesses usually resolve within a few days. Cyclospora does not. It can last for weeks if not treated,” said Dr. Supriya Rao, a gastroenterologist. “Symptoms can improve, then worsen again. If you have persistent watery diarrhea, fatigue, loss of appetite, abdominal pain, and you can remember eating fresh produce, lettuce or salad, I’d move cyclospora higher on my list of culprits.”
Because cyclosporiasis is a protozoal infection, it can also take your body longer to clear than a bacterial infection like salmonella, Mordue said.
And not all diarrhea caused by common foodborne illnesses is the same. Salmonella, which is a bacterial infection, often causes bloody diarrhea because it can deeply infect your intestinal tissue, Mordue said. Meanwhile, cyclosporiasis typically causes profuse, watery, non-bloody diarrhea, she said.
But you would need to test your poop to know for sure what is causing you diarrhea. “The diagnosis requires a stool test that specifically looks for cyclospora,” Rao said. “If you think you have cyclospora, you should get tested and not rely on appearance alone.”
2. If you already have tummy issues, like IBS, notice what feels unusual.
“If someone already has GI issues, they should be familiar with their symptoms and their flares,” Rao said, which is why she said to watch out for additional symptoms linked to cyclosporiasis such as persistent diarrhea, fatigue or a low-grade fever.
“An IBS [Irritable Bowel Syndrome] flare should not last for weeks. If your symptoms are more severe or are lasting longer, I’d let your physician know,” Rao said.
Mordue said to notice “something out of the ordinary” from your baseline if you’re used to having stomach pains or gastroenteritis, noting that “strong fatigue” has been associated with cyclosporiasis in particular.
The good news is that cyclosporiasis can be treated with seven to 10 days of the antibiotic trimethoprim-sulfamethoxazole. But to get the medication, you need to see a healthcare provider, which is what experts suggest doing if you suspect you have cyclosporiasis.
Cyclosporiasis is not a life-threatening illness for healthy people, but there are people that are especially vulnerable to this sickness.
“If the individual is older and immune suppressed, they might not be able to tolerate the infection or the dehydration, as well as somebody who might be younger,” Mordue said.
“The key thing is if [your diarrhea] lasts longer than about two or three days, regardless, you probably should see a physician, especially if it’s a lot of diarrhea and it’s fairly frequent,” Mordue said.
