Abstract
Cyclospora cayetanensis is a parasite that causes intestinal disease that can be especially severe in immunocompromised patients. Most cases occur in tropical and subtropical areas, and in industrialized countries their diagnosis is mostly linked to international travel or the ingestion of imported food. We describe this case of severe diarrhoea in a patient with diffuse large B cell lymphoma and no epidemiological risk factors that was successfully treated with trimethoprim-sulfamethoxazole (TMP-STX). C. cayetanensis is a pathogen that should be taken into account in patients with chronic diarrhoea, especially immunocompromised patients, even when no epidemiological risk factors are present.