Cyclospora has recently been implicated in outbreaks associated with U.S. produce imported from Mexico. Outbreaks have also been linked to drinking water. Information on the sources and occurrence of this organism are very limited. Currently, only humans and possibly primates are believed to be infected by this parasite. Our goal is to determine if produce in the United States is at risk of contamination from irrigation waters contaminated with human sewage (e.g., from faulty/leaky septic systems or compromised sewer pipes) and treated wastewater effluents that could potentially be discharged into surface waters used for the irrigation of food crops. Our specific objectives are to: a) determine the occurrence of C. cayetanensis in irrigation waters in Arizona and Texas. This will allow a determination of any risk from C. cayetanensis and to identify areas of potential risk; and b) to determine the occurrence of C. cayetanensis in raw sewage and treated wastewater effluents in produce producing areas such as Yuma, AZ and El Paso, TX. This data will allow for an assessment of the incidence of C. cayetanensis infection among these communities. In addition, treated wastewater effluents are sometimes released into watersheds and could potentially impact irrigation waters. This study will allow us to determine if any risks exist from Cyclospora in irrigation waters from these two regions.