A heart transplant patient presented with a five-month history of chronic watery diarrhea, significant weight loss, and intestinal malabsorption. Initial investigations for common pathogens were negative. Diagnosis was challenging, but ultimately, Cyclospora cayetanensis oocysts were identified in stool samples using modified acid-fast staining and confirmed by PCR. This led to a diagnosis of chronic cyclosporiasis. The patient, being immunosuppressed, experienced a prolonged and severe course of infection. Treatment with trimethoprim-sulfamethoxazole resolved the symptoms.
Key note: Cyclosporiasis should be considered in immunosuppressed patients with chronic diarrhea and malabsorption, even when initial tests are negative, requiring specific diagnostic methods.