Improve food safety by reducing contamination of fresh produce by improving detection and determining the sources and reducing transmission of protozoan parasites infectious for humans. Objective 1: Improve detection methods for Cryptosporidium, Giardia, and other zoonotic parasites. a) Develop new immunofluorescence and aptamer technologies applicable to detection of zoonotic parasites on fresh fruits and vegetables and in irrigation water and produce washwater. b) Determine effective washing agents and methods for recovering contaminating parasites from the surface of fresh produce. c) Develop a protocol using amplified fragment length polymorphism analysis (AFLP) to simultaneously detect multiple infectious organisms thereby reducing the need for multiple testing. Objective 2: Develop prevention and treatment strategies against zoonotic cryptosporidiosis and giardiasis. a) Test anti-viral drugs against virus found inside Cryptosporidium parvum stages to inhibit virus and parasite replication. b)Test probiotics in mouse models for prevention of cryptosporidiosis. Objective 3: Elucidate the epidemiology of zoonotic Cryptosporidium, Giardia, Blastocystis and Microsporidia by identifying unique and emerging genotypes using molecular tools. a) Determine subtypes of Blastocystis and Microsporidia found in food animals that match pathogenic subtypes in humans. b) Identify emerging zoonotic genotypes and subgenotypes of Cryptosporidium and Giardia with potential to be foodborne pathogens from samples of irrigation water and from manure spread on crop fields.