Cyclospora cayetanensis is
a coccidian parasite that causes acute and chronic diarrhea in both immunocompetent
and immunocompromised hosts. Cyclospora is phylogenetically
related to other coccidian parasites, including Cryptosporidium,
Isospora, Toxoplasma, and Sarcocystis. Initially
described as cyanobacteria-like (blue-green algae) bodies in the
stools of patients with prolonged diarrhea, anorexia, and fatigue,1Cyclospora species
are now known to be ubiquitous, infecting a variety of animals,
including reptiles, insectivores, and rodents. However, Cyclospora
cayetanensis is the only species that is known to infect
humans.2,3 Although the organism has been recovered
in the stool of affected individuals from numerous regions—including
North America, Central America, South America, Caribbean Islands,
eastern Europe, South Africa, Southeast Asia, India, Nepal, Peru,
and Haiti—infection appears to be most common in tropical
and subtropical countries.4