Cyclosporiasis cases reach 1,428 in Michigan and Ohio across 18 states

Cases of cyclosporiasis have been confirmed in at least 18 states. As of Thursday, Michigan reported 1,251 cases and Ohio reported 177 cases. The parasite Cyclospora cayetanensis causes the intestinal infection. Symptoms include severe watery diarrhea, nausea, vomiting, abdominal pain or bloating.

Testing requirements Routine laboratory stool tests do not include Cyclospora, so providers must specifically request testing, according to the Centers for Disease Control and Prevention. Individuals may need to submit several stool samples on different days because the parasite may not shed enough to be detected in one sample.

The most sensitive detection methods are stool PCR tests or stool microscopy, Dr. Jeanne Marrazzo, CEO of the Infectious Diseases Society of America, told ABC News. PCR analysis identifies parasite DNA; microscopy looks for characteristic Cyclospora oocysts under a microscope.

Tracing infections The time between infection and illness is typically about one week but can range from two days to two weeks or more. The long incubation period complicates efforts to identify the source. When a case is confirmed, the local health department contacts the individual for an interview.

Officials ask about symptom onset, duration, and specific restaurants or grocery stores visited 12 days before illness, along with dates and food items. Most people with diarrhea do not seek medical care, Marrazzo said. Persistent symptoms are a reason to consult a physician.