Epidemiology of Cyclospora cayetanensis: A review focusing in endemic areas.

Cyclospora cayetanensis is an intestinal coccidian protozoon that has emerged as an important cause of endemic or epidemic diarrhoeal illness in children and adults worldwide. Humans appear to be the only natural hosts. However, the role of animals as natural reservoirs is uncertain but of increasing concern. Human-to-human spread of the parasite occurs indirectly via the environment through oocysts in contaminated water, food or soil. In endemic areas, risk factors associated with the infection include contaminated water or food, contact with soil or animals, type of sanitation and low socioeconomic status. Infections linked to soil contact provide reasons to believe that this route of spread may be more common than realised in disadvantaged community settings. C. cayetanensis is an important cause of traveller's diarrhoea and numerous large foodborne outbreaks associated with the globalisation of the food supply and importation of fruits and vegetables from developing countries have occurred. Waterborne outbreaks have also been reported. Implementation of measures to prevent or control the spread of Cyclospora oocysts in the environment is critical. In endemic areas, the most important steps to prevent infection are improving environmental sanitation and health education. Significant gaps remain in our understanding of the epidemiology of human cyclosporiasis that highlight the need for continued research in several aspects of C. cayetanensis.