A mysterious outbreak of a parasite causing explosive, watery diarrhea has infected at least 145 people across 20 states, with officials currently unable to identify the source. The U.S. Centers for Disease Control and Prevention (CDC) and other public health authorities are investigating clusters of the illness, known as cyclosporiasis.
As of June 16, individuals ranging in age from 5 to 86 years contracted the parasite, Cyclospora cayetanensis. Twenty people have been hospitalized, but no deaths have been reported. New York has reported the highest number of cases, with Texas and Illinois following.
Unlike typical cyclosporiasis infections, which are often contracted during travel abroad through contaminated food or water, none of the affected individuals reported recent travel outside the U.S. This has led health officials to suspect that the parasite was acquired through food consumed domestically. There is also no evidence to suggest the parasite spreads from person to person.
Cyclosporiasis symptoms typically appear about a week after infection and primarily affect the intestines. Key symptoms include watery diarrhea, severe cramping, nausea, vomiting, loss of appetite, bloating, fatigue, and sometimes a low-grade fever. While the infection can resolve on its own, symptoms can persist for a month or longer if untreated, potentially leading to dehydration.
Treatment usually involves a course of antibiotics, such as trimethoprim-sulfamethoxazole. The CDC recommends safe food handling practices, including proper preparation and storage, to help prevent infection. While the risk is often associated with food from tropical or subtropical regions outside the U.S., consuming fresh, imported produce can also pose a risk.
Previous outbreaks in the U.S. have been linked to various produce items, including cilantro, raspberries, sweet peas, mesclun lettuce, and basil. In 2018, a significant outbreak infected nearly 400 people through contaminated McDonald's salads. The current investigation is ongoing, and officials acknowledge that the actual number of cases may be higher than reported, with potential infections in states not yet identified.