Inactivation of Cryptosporidium spp. oocysts with ozone and ultraviolet irradiation evaluated by in vitro excystation and animal infectivity

Abstract

Cryptosporidium parvum and Cryptosporidium muris oocysts were exposed to ozone and/or ultraviolet(UV) lamp in bench-scale batch reactors. The effect of ozone, UV, and sequential disinfection method on two kinds of oocysts were determined with in vitro excystation and animal infectivity test. The results of ozone exposure experiments showed that the required Ct values were about 3 and 8 mg · min./L for 2-log and 3-log reduction ininfectivity of C. parvum oocysts at room temperature, respectively. But larger values of Ct were needed at low temperature. In the case of sequential disinfection methods with ozone and UV, more than 1-log reduction in infectivity was achieved with 15 sec. of UV irradiation. There was no significant correlation between the excystation ratios and the reduction ratios in infectivity. Moreover, the results of dose-response of animal infectivity test indicated the possibility of a new method to evaluate the infectivity of Cryptosporidium parvum oocysts.

Criptosporidiose: uma revisão sobre a sua implicação na conservação dos mamíferos aquáticos

“…Sendo assim, entre os métodos de inativação recomendados, verifica-se a necessidade de avaliação constante no sistema de filtração, bem como a utilização do ozônio ou a instalação de um sistema ultravioleta nos oceanários e piscinas (Clancy et al 2000, Kanjo et al 2000, Causer et al 2006. Além das medidas citadas, deve-se ainda evitar a presença dos oocistos nos alimentos ofertados e incentivar normas de higiene pessoal entre os tratadores e técnicos envolvidos na manejo dos animais.…”

Inactivation of Cryptosporidium parvum by Ultrasonic Irradiation

“…For example, several thousands of people in Saitama, Japan were infected in 1996. Due to such large-scale outbreaks of Cryptosporidiosis , many substitutable techniques for chlorination, such as filtration (), ozonation ( , ), ultraviolet (), and their synergetic disinfection ( − ) have been developed for inactivation of C. parvum . Ozonation is one of the promising methods for inactivation of C. parvum .…”

Caracterización molecular de aislamientos de <i>Cryptosporidium</i> spp. de cerdos en Argentina

“…Se han realizado muchos estudios sobre estrategias de desinfección y filtración para el agua potable (Rose et al, 1997). El ozono y la luz ultravioleta han demostrado ser eficaces en la desinfección de ooquistes en instalaciones de tratamiento de agua (Clancy et al, 2000;Kanjo et al, 2000;Rose et al, 1997). El tratamiento con productos químicos combinados como el cloro y la monocloramina o el ozono y la monocloramina ha demostrado una mayor desinfección que la exposición a un solo producto químico (Fayer, 2004).…”