Microsporidia and Cyclospora: Epidemiology and assessment of risk from theenvironment

Two classes of parasites with an environmental stage in their lifestyle hav e recently emerged as significant gastrointestinal pathogens for humans. Mi crosporidia represent a group that contains a number of genera related to t he genus Cryptosporidium. They are generally transmitted via direct human t o human contact, but can survive in water and food, and recently have been found in surface water used as drinking source water. Their most common hos t range is in patients with clinical AIDS. Limited work to date suggests th e group is susceptible to chlorine achievable CxT (concentration x time) va lues and is coagulated by filtration. Cyclospora cayetanensis is a species of parasite that has caused outbreaks from contaminated food. Its major ris k is from the use of inadequately treated water used for irrigation. Cyclos pora can infect normal and immunosuppressed hosts. Current information rega rding the lifestyle, transmission, and control of both groups of parasites are discussed, with a health risk assessment analysis.