C. cayetanensis is a protozoan parasite from the phylum Apicomplexa, a group of organisms closely related to pathogens that affect birds. These parasites cause a GI infection known as cyclosporiasis. C. cayetanensis is a coccidian parasite, which means those who are infected shed oocysts in their feces. Because the oocysts that are shed in the stool must mature outside the host in order to become infective to someone else, direct person-to-person transmission through the fecal-oral route is unlikely. If an infected person contaminates the environment and the oocysts have adequate time to mature, indirect transmission can occur. However, the time required for the oocysts to mature is thought be days to weeks, so indirect transmission is rare.

People of all ages are at risk for C. cayetanensis infection. It is seen worldwide but is more common in tropical areas. The infection has been identified in travelers to areas such as Peru, Nepal, Guatemala, Haiti, and Indonesia. Infections in the United States tend to peak during the spring and summer months.