A parasite in contaminated food and water is causing severe diarrhea for people in at least 34 states. Maryland’s cases have doubled since last week. Cyclosporiasis, an illness caused by the microscopic parasite Cyclospora cayetanensis, is not new but it has attracted attention recently as multiple states have reported increased incidents so far this year compared to the same period of 2025. From May 1 through July 13, there were 1,645 confirmed cases of cyclosporiasis in the United States and more than 5,100 others that are suspected to be the illness, according to the Centers for Disease Control and Prevention. The Maryland Department of Health has confirmed a total of 69 cases this year, including 65 from May 1 through July 14. Symptoms of cyclosporiasis include diarrhea, sometimes explosive; loss of appetite; weight loss; nausea; vomiting; and fever. While health officials have not yet determined the source of the recent spike in U.S. cases, main culprits include contaminated produce such as lettuce, basil, cilantro, raspberries, and snow peas. Dr. Reezwana Chowdhury, a gastroenterologist at Johns Hopkins Hospital, said she is not allowing her family to eat those culprit foods and is recommending others do the same. “My general motto right now is: if it doesn’t have an outside skin protecting it, I personally am avoiding it,” she said. Although the Maryland health department is advising residents to wash fruits and vegetables before eating them to reduce their risk for foodborne illness, this can be difficult with certain foods. Raspberries, for example, have “a lot of nooks and crannies in there, so it’s really hard to wash it out thoroughly enough,” Chowdhury said. But that doesn’t mean families should forgo fruits and vegetables altogether, Chowdhury emphasized. Produce like melons and pineapples can be peeled and eaten safely. “Anything you can just basically get the exterior off, and then you’re getting the inside of the fruit are all appropriate,” she said. If residents are handling any potentially contaminated fruits and vegetables, Chowdhury said they should wash them as thoroughly as possible, then wash their hands with soap and water very well. Heating foods to a temperature over 154 degrees would kill this parasite, Chowdhury said. Frozen ingredients also appear safe to consume. Symptoms could take at least seven days to develop after ingesting a contaminated product. If an individual is experiencing any symptoms of cyclosporiasis, they should consult their healthcare provider. “If they have relentless explosive diarrhea, weight loss, unbearable abdominal pain, nausea, vomiting, all of that, I do think they should talk to a healthcare provider,” Chowdhury said. “And then when they do talk to them, I think it’s important for them to say, ‘Hey, I do eat a lot of salads, fruits, vegetables, or I’ve traveled somewhere that could have potentially put them at risk.’” That provider should order the appropriate stool testing – not just a standard stool culture, but one that tests the stool for parasites and eggs. Vulnerable groups, such as older adults, immunocompromised individuals, or young children, should especially seek medical attention in order to potentially start antibiotics. ...read more read less