Submitted to: Society of Protozoologists International Workshop on Opportunistic Protists
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 2001
Publication Date: December 1, 2001
Citation: PHELPS, K.K., LINDSAY, D.S., FAYER, R., SUMNER, S.S. EFFECTS OF ORGANIC ACIDS AND HYDROGEN PEROXIDE ON THE SURVIVAL OF CRYPTOSPORIDIUM PARVUM OOCYSTS IN UNPASTEURIZED FRUIT JUICES. SOCIETY OF PROTOZOOLOGISTS INTERNATIONAL WORKSHOP ON OPPORTUNISTIC PROTISTS. 2001.
Cryptosporidium parvum has historically been associated with waterborne outbreaks of diarrheal illness. While more recently, foodborne cryptosporidiosis has been associated with unpasteurized apple cider. Infectious oocysts are shed in the feces of common ruminants like cattle and deer in/near orchards. The addition of organic acids (citric, malic, tartaric) and/or hydrogen peroxide (H2O2) to fruit juice to inhibit survival of C. parvum without using pasteurization was analyzed in this study. Chemicals were added on a wt/vol basis to apple cider, orange juice, and grape juices. Concentrations ranging from 1%-5% organic acids and 0.025%-3% H2O2 were evaluated. Oocyst viability was analyzed with a cell culture infectivity assay, using a human ileocecal cell line (HCT-8). Cell monolayers were infected with 106 treated oocysts. Parasitic life stages were visualized through immunohistochemistry and 100 microscope fields counted per monolayer. As little as 0.025% hydrogen peroxide completely inhibited the survival of C. parvum oocysts in apple cider after 24 hours; however incubation with the same concentration of hydrogen peroxide for two hours resulted in only 68% reduction of viable organisms. Malic acid at 5% reduced viability by 94.7%. Similar results were observed for all juices. Similarly, addition of 0.10% H2O2 to water caused a 100% decrease in viability after 2 hours. The effects of catalase on H2O2 decomposition were evaluated over 24 hours and no change in effect on oocyst viability was observed. Further analysis will better evaluate if H2O2 is inhibiting excystation directly or through