Occurrence of Cryptosporidium and Giardia in irrigation water and its impact on the fresh produce industry.

In Mexico, relatively few studies have examined the presence of protozoan parasites from surface waters with irrigation and wash-water applications in the fresh produce industry. In this study, the presence of Cryptosporidium oocysts and Giardia cysts in surface water for irrigation, washing and disinfecting applications was evaluated. In addition, the occurrence of Cryptosporidium oocysts and Giardia cysts was determined in wash-water tanks at selected packinghouses. The occurrence of both Cryptosporidium and Giardia was determined by an immunofluorescent technique. Forty-eight percent of the surface water samples tested positive for Cryptosporidium oocysts and 50% tested positive for Giardia cysts. Concentration ranges for Cryptosporidium oocysts and Giardia cysts were 17-200 and 17-1633 per 100 litres, respectively. Sixteen percent of the wash-water tanks tested positive for Cryptosporidium oocysts and 83% were positive for Giardia cysts with concentrations ranging from 1-133 oocysts and 100-533 cysts per 100 litres, respectively. The presence of protozoan parasites in surface water for irrigation and packinghouse operations suggests that there may be a risk of contamination of fresh produce as protozoan oocysts/cysts might come in contact with and attach to crop surfaces posing a risk of infection to consumers who eat these products.