Cyclospora is a coccidian, previously referred to as a cyanobacterium-like body, with an epidemiology similar to that of Cryptosporidium parvum. In recent years, several studies have shown that Cyclospora is not a rare opportunistic pathogen but rather is the cause of common, worldwide intestinal infections in healthy adults and children. Previous reports of diarrhea resulting from Cyclospora sp. have been linked to travelers and immunocompromised patients. The species has a worldwide distribution. Although Cyclospora infection has been reported from Southeast Asia, Papua New Guinea, Indonesia, India, Pakistan, Nepal, the Middle East, North Africa, the United Kingdom, the Caribbean, the United States, Central America, and South America, the true prevalence of this parasite in any population is unknown. The parasite is associated with prolonged self-limiting and relapsing watery diarrhea, anorexia, fatigue, and sometimes myalgia. Fever is infrequent.