Environmental contamination with protozoan parasite infective stages: biology and risk assessment.

In the present paper some aspects of the biology and various factors influencing the potential for environmental contamination with protozoan parasites infective stages implicated in water and foodborne diseases are described. The major protozoan species that affect humans are Entamoeba histolytica, Acanthamoeba sp., Neagleria sp. Giardia intestinalis, Cryptosporidium parvum, Cyclospora cayetanensis, Toxoplasma gondii, Isospora/Sarcocystis sp. Encephalitozoom intestinals and Enterocytozoon bieneuisi. These parasites exist in the environment as oocyst, cysts or spores, which are the transmissive stages in many environmental conditions, e.g. water, soil, food as well as being infective stages to subsequent generation of hosts. Global concern with parasitic contamination of our environment must influence development of better detection methods and of evaluation and risk assessment of these infections. In this paper, the biology, waterborne and foodborne transmission, as well as methods for detection and control of Cryptosporidium parvum, Giardia intestinals and Toxoplasma gondii will be described.