As of June 16, the Centers for Disease Control and Prevention (CDC) is tracking 145 cases of Cyclospora cayetanensis, a microscopic parasite that causes explosive diarrhea, across 17 states. Health officials emphasize this is a seasonal occurrence and highly treatable, though difficult to trace. Patients range in age from 5 to 86 years, with 61% being women. Twenty patients were hospitalized, and no deaths have been reported.
Geographic Distribution and Reporting
The majority of cases are concentrated in New York State, with between 31 and 80 infections reported. Texas and Illinois also have significant case numbers. Other states with confirmed cases include Alaska, Colorado, Connecticut, Florida, Georgia, Louisiana, Massachusetts, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, and Wisconsin.
Dr. Bobbi Pritt, Chair of the Division of Clinical Microbiology at the Mayo Clinic, told HuffPost that the CDC's numbers likely represent only a fraction of actual infections. "It never really completely reflects all the cases," she said, "because of all those things that go into play of someone thinking about it, ordering the right test, and making sure it's reported."
Seasonal Patterns and Transmission
Cyclosporiasis cases typically rise during spring and summer, with the official season considered May 1 through August 31. This year, the first reported case was on May 13. The parasite thrives in tropical and subtropical regions, and its prevalence increases with fresh produce consumption.
"This is a season where we get more fresh produce coming in," Pritt explained. "People are eating more salads and herbs and berries and vegetables that are often eaten raw, and therefore, it's more likely that if there are parasites present, they'd still be active in a live plant instead of being cooked, which would inactivate them."
Unlike norovirus, Cyclospora is not transmitted person-to-person. "If one person in the household is sick, they're not going to be able to spread it to other people," Pritt said. Infection occurs through ingestion of contaminated food or water.
Sources and Detection
Imported fresh produce, including basil, cilantro, raspberries, and snow peas, has been linked to past outbreaks. The parasite is shed in human stool and likely contaminates soil where produce is grown for export. "It isn't like some of the other parasites we find in the U.S., where they could be shed by animals. This is really a human disease, and it's associated with poor hygiene, human fecal waste entering the food supply, and that food then being shipped to the U.S. via imported produce," Pritt said.
Detection requires specialized testing beyond standard stool analysis. Cyclospora is not identified by simple stool tests; an additional stain is needed. The CDC has developed molecular genetic analyses to examine parasite DNA, helping track outbreaks across states. "That really helps them track it," Pritt said. "They could type the parasite from the people infected in all those different states and see if it's even coming from the same source."
Symptoms and Treatment
Symptoms typically appear within a week of consuming contaminated food or water. "It lasts a little longer than the typical 24-hour stomach bug," Pritt said. "The hallmark is really prolonged watery diarrhea, and it's very often accompanied by abdominal cramping, abdominal pain, bloating, nausea, fatigue and loss of appetite."
The infection can resolve without antibiotics, but without treatment, symptoms may persist for over a month. Fatigue can continue even after gastrointestinal symptoms subside, according to the CDC.
Prevention and Safety
To reduce risk, wash hands with soap and water before and after handling raw fruits and vegetables. Produce should be rinsed under running water before consumption, even if labeled "prewashed." Firm foods like melons and cucumbers should be scrubbed with a produce brush. However, chemical disinfection is unlikely to fully kill the Cyclospora parasite.
"For the most part, I would say our produce is pretty safe," Pritt said. "Most of the time, fresh produce in general is very safe, and it's actually an important part of a healthy diet, so we wouldn't want people to stop eating it. But I do think it's important to note that at this point, if someone becomes symptomatic and they develop prolonged watery diarrhea, they go to their healthcare provider."
