Interventions For Decontamination

Various sanitizers and disinfectants have been evaluated for cryptosporidium. Oocysts will remain viable if kept in moist environments, but are very sensitive to desiccation. Moist heat treatments or pasteurization of cryptosporidium oocysts at 45°C for 5 to 20 minutes inactivate the parasite [84].

Chemical agents commonly used for disinfection of contaminated environmental surfaces and medical devices such as endoscopes have been evaluated for their effect on cryptosporidium viability. Exposure of C. parvum to steam, ethylene oxide, and Sterrad 100 and hydrogen peroxide at concentrations of 6

and 7.5% for 20 minutes resulted in population reductions of 3 logs or greater. Peracetic acid (0.2% for 20 minutes), sodium hypochlorite (5.25% for 10 minutes), a phenolic, a quaternary ammonium compound (10 minutes), 2% glutaraldehyde (45 minutes), and ortho-phthalaldehyde (20 minutes) did not completely inactivate oocysts [85].

The effect of ultraviolet radiation from low- and medium-pressure mercury arc lamps on Cryptosporidium parvum oocysts has been evaluated. Two and three log units inactivation have been achieved at approximately 10 and 25mJ/cm2/sec, respectively [86]. Use of static mixers for dissolution of ozone in drinking water treatment plants may contribute to C. parvum inactivation [87]. Flash pasteurization of cider inoculated with cryptosporidium oocysts at 70 or 71.7°C, both for 10 or 20 seconds, reduced viability by at least 4.9 logs (or 99.999%) when determined using a tissue culture assay. A 3.0 log (99.9%) and 4.8 log (99.9985) inactivation were achieved when oocysts were treated for 5 minutes at 70 or 71.7°C, respectively. Current practices of flash pasteurization in the juice industry are sufficient to inactivate contaminant oocysts [88]. An electrochemically produced mixed-oxidant solution (MIOX; LATA Inc.) was considerably more effective in inactivating Cryptosporidium parvum oocysts than free chlorine. A 5 mg/l dose of mixed oxidants produced a >3 log (>99.9%) inactivation of Cryptosporidium parvum oocysts in 4 hours [89].

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