Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/10/2007
Publication Date: 11/5/2007
Citation: Kniel, K., Shearer, A., Cascarino, J., Wilkins, G., Jenkins, M.C. 2007. High hydrostatic pressure and uv light treatment of produce contaminated with eimeria acervulina as a cyclospora cayetanensis surrogate. Journal of Food Protection. 70:2837-2842. Interpretive Summary: Outbreaks of cyclosporosis, and intestinal disease caused by the protozoan parasite Cyclospora cayetanensis, have been reported worldwide. Most outbreaks appear to be associated with consumption of C. cayetanensis-contaminated fruits and vegetables. At present it is difficult to study C. cayetanensis because the parasite only infects humans (i.e. there is no animal model in which to propagate the parasite). Recent studies have shown that Cyclospora is closely related to the protozoan parasite Eimeria, which is a causative agent of avian coccidiosis. In this study, Eimeria oocysts were used as a surrogate for C. cayetanensis. Fruits and vegetables were contaminated with Eimeria oocysts, and then exposed to ultraviolet radiation (UV) or high pressure processing (HPP). Eimeria oocysts were removed from the contaminated food and inoculated into chickens to determine if either UV or HPP treatment neutralized infectivity. Animals inoculated with UV- or HPP-treated Eimeria oocysts exhibited no clinical signs of coccidiosis nor shed oocysts. These findings suggests that UV or HPP treatment may be effective means of destroying Eimeria, and possibly Cyclospora on fruits and vegetables.
Technical Abstract: The prevalence, size, genome, and life cycle of Eimeria acervulina make this organism a good surrogate for Cyclospora cayetanensis, a protozoan that causes gastroenteritis in humans, including recent outbreaks in the United States and Canada associated with contaminated raspberries and basil. Laboratory studies of C. cayetanensis are difficult because of the lack of readily available oocysts and of infection models and assays. UV radiation and high-hydrostatic-pressure processing (HPP) are both safe technologies with potential for use on fresh produce. Raspberries and basil were inoculated with sporulated E. acervulina oocysts at high (106 oocysts) and low (104 oocysts) levels, and inoculated and control produce were treated with UV (up to 261 mW/cm2) or HPP (550 MPa at 40 degrees C for 2 min). Oocysts recovered from produce were fed to 3-week-old broiler chickens, which were scored for weight gain, oocyst shedding, and lesions at 6 days postinoculation. Oocysts exhibited enhanced excystation on raspberries but not on basil. Birds fed oocysts from UV-treated raspberries had reduced infection rates, which varied with oocyst inoculum level and UV intensity. Birds fed oocysts from UV-treated raspberries (104 oocysts) were asymptomatic but shed oocysts, and birds fed oocysts from UV-treated basil (104 oocysts) were asymptomatic and did not shed oocysts. Birds fed oocysts from HPP-treated raspberries and basil were asymptomatic and did not shed oocysts. These results suggest that UV radiation and HPP may be used to reduce the risk for cyclosporiasis infection associated with produce. Both treatments yielded healthy animals; however, HPP was more effective, as indicated by results for produce with higher contamination levels.