Cyclospora and Cystoisospora

Cyclospora cayetanensis and Cystoisospora belli (formerly Isospora belli) are unicellular coccidian parasites causing gastrointestinal disease, mainly in the tropical and subtropical climates. Ingestion of sporulated oocysts in fecal contaminated food, water or other transmission vehicle causes infection in susceptible subjects. Thus, they are related to poor sanitation areas, affecting young children, the elderly, and immunocompromised people, albeit in most of the cases infections are self-limiting. Also, they are among parasites causing “traveler's diarrhea” hitting persons never exposed to the parasite before, which have gone to endemic countries. Cases of cyclosporiasis in North America and Europe were also associated to importation of contaminated fresh food. Hence, globalization can increase the number of infections overworld, along with climate change. Both cyclosporiasis and cystoisosporiasis are more severe in immunosuppressed persons, notably in HIV-infected patients, being considered as opportunistic. C. belli and C. cayetanensis, together with Cryptosporidium, may also be found in the biliary system. For both C. belli and C. cayetanensis first line treatment is based on trimethoprim-sulfamethoxazole. In immunocompromised persons chronic cystoisosporiasis may also involve lymph nodes, liver, pancreas and spleen, and requires indefinite prophylaxis. Along with epidemiological and clinical features, treatment, control and prevention, parasites biology and diagnostic methods are illustrated.