title: Ozone inactivation of Cryptosporidium parvum in demand-free phosphate buffer determined by in vitro excystation and animal infectivity.
abstract: Inactivation of Cryptosporidium parvum oocysts by ozone was performed in ozone demand-free 0.05 M phosphate buffer (pH 6.9) in bench-scale batch reactors at 7 and 22 degrees C. Ozone was added to each trial from a concentrated stock solution for contact times ranging from 5 to 15 min. The viability of the control and treated oocysts was determined by using in vitro excystation and infection in neonatal CD-1 mice. It was found that excystation consistently underestimated inactivation when compared with animal infectivity (P < or = 0.05). As inactivations increased, the difference between excystation and infectivity also increased. The inactivation kinetics of C. parvum by ozone deviated from the simple first-order Chick-Watson model and was better described by a nonlinear Hom model. The use of the Hom model for predicting inactivation resulted in a family of unique concentration and time values for each inactivation level rather than the simple CT product of the Chick-Watson model.
authors.affiliation: Department of Civil Engineering, University of Alberta, Edmonton, Canada.
authors.forename: G R
authors.initials: GR
authors.lastname: Finch
authors.forename: E K
authors.initials: EK
authors.lastname: Black
authors.forename: L
authors.initials: L
authors.lastname: Gyürék
authors.forename: M
authors.initials: M
authors.lastname: Belosevic
mesh_terms: D000818:Animals; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000254:growth & development* / Q000472:pathogenicity*; D051379:Mice; D008954:Models, Biological; D010126:Ozone / Q000494:pharmacology*
chemical_list: D010126:Ozone