Cyclospora cayetanensis: a review of an emerging parasitic coccidian.

Cyclospora cayetanensis is a sporulating parasitic protozoan that infects the upper small intestinal tract. It has been identified as both a food and waterborne pathogen endemic in many developing countries. It is an important agent of Traveller's Diarrohea in developed countries and was responsible for numerous foodborne outbreaks in the United States and Canada in the late 1990s. Like Cryptosporidium, infection has been associated with a variety of sequelae such as Guillain-Barré syndrome, reactive arthritis syndrome (formally Reiter syndrome) and acalculous cholecystitis. There has been much debate as to where to place C. cayetanensis taxonomically due to its homology with Eimeria species. To date, the only genomic DNA sequences available are the ribosomal DNA of C. cayetanensis and three other species; within these a high degree of homology has been observed. This homology and the lack of sequence data from other Cyclospora species have hindered identification methods.