Health officials are investigating thousands of suspected cases of cyclosporiasis nationwide, a parasitic illness transmitted through contaminated food and water that causes prolonged diarrhea. As of July 14, the Centers for Disease Control and Prevention confirmed 1,645 illnesses and were investigating an additional 5,100 suspected cases.
The primary symptom of cyclosporiasis is "explosive" watery diarrhea. Differentiating it from common foodborne illnesses, such as those caused by salmonella or norovirus, can be challenging due to a longer incubation period and the lack of a clearly identified food source for the current outbreak. Previous U.S. outbreaks have been linked to produce including cilantro, basil, snowpeas, mesclun lettuce, and raspberries. Michigan health officials recently indicated lettuce as a potential cause for the current surge.
Furthermore, not everyone infected with the parasite experiences 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.
Experts note that the duration of symptoms is a key differentiator. While most foodborne illnesses resolve within a few days, cyclosporiasis can persist for weeks if untreated and may involve symptoms that improve and 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," said Dr. Supriya Rao, a gastroenterologist.
Unlike bacterial infections like salmonella, which can cause bloody diarrhea by infecting intestinal tissue, cyclosporiasis typically results in profuse, watery, non-bloody diarrhea. Definitive diagnosis requires a stool test specifically looking for the cyclospora parasite.
Individuals with pre-existing gastrointestinal conditions, such as Irritable Bowel Syndrome (IBS), are advised to monitor for unusual symptoms. An IBS flare should not typically last for weeks, and persistent or severe symptoms, along with fatigue or a low-grade fever, could indicate cyclosporiasis. Mordue advised paying attention to "something out of the ordinary" compared to one's usual gastrointestinal experiences, noting that significant fatigue is often associated with this parasitic infection.
Cyclosporiasis is treatable with a seven- to 10-day course of the antibiotic trimethoprim-sulfamethoxazole, requiring a healthcare provider's prescription. While generally not life-threatening for healthy individuals, older adults and immunocompromised individuals may be more vulnerable to severe complications from the infection and dehydration.
Health experts recommend consulting a physician if diarrhea persists for more than two or three days, especially if it is frequent and severe.