Chapter 33 - Inactivation of Cryptosporidium parvum Oocysts by Low Pressure UV-light

Abstract

Conventional treatment processes and chemical disinfection of water are not efficacious for the removal as well as the inactivation of Cryptosporidium parvum oocysts from large water supplies. One of the most promising alternative methods for the oocyst inactivation is the Ultraviolet (UV) irradiation of drinking water. This chapter describes the inactivation of C. parvum oocysts by low-pressure UV and the infectivity assay of low concentrations of C. parvum oocysts not exposed to UV-light. Use of the different strains of C. parvum oocysts can yield variability in the infectivity and inactivation experiments because of the high degree of biological variability of the parasites, but most probably this can affect the inactivation results only by low range of applied doses. The results of this investigation reveal that UV irradiation has the potential for effective inactivation of oocysts for disinfection purposes. The SCID-mice model indicates a reliable model for infectivity assays and is useful for application to similar situations with low numbers of potentially infectious oocysts purified from natural water samples, or to evaluate the efficiency of disinfection and inactivation of oocysts.