UV light inactivation of Cryptosporidium oocysts

Abstract

Animal infectivity studies demonstrate the efficacy of pulsed and advanced UV in inactivating Cryptosporidium oocysts. Cryptosporidium parvum oocysts are highly resistant to conventional chlorine‐based disinfectants. The authors tested two innovative electrotechnologies that use ultraviolet (UV) light and found that both pulsed UV and advanced UV inactivated Cryptosporidium oocysts. The advanced UV system achieved >4‐log inactivation as determined in animal infectivity studies using the neonatal mouse model. With the pulsed UV system, oocyst inactivation was also noted in the process control (non‐UV‐exposed oocysts), suggesting that some oocyst inactivation may have occurred independently of UV exposure. Irrespective of this, both technologies appear to be effective and novel ways to treat drinking water and to provide an additional significant barrier that helps protect public health.

Particle-Associated Viruses in Water: Impacts on Disinfection Processes

“…Cryptosporidium parvum at economical doses (Clancy et al, 1998), UV disinfection is also now considered a viable primary disinfectant of drinking water in North America. In wastewater treatment, chlorination and UV disinfection are commonly applied.…”

Cell Culture-Taqman PCR Assay for Evaluation of Cryptosporidium parvum Disinfection

“…Although some water treatment processes remove oocysts, any oocysts that break through represent a potential threat to human health due to their relative chlorine resistance. Various methods of disinfection have been investigated by a number of research groups; these methods include UV light (4,10,11,13,14,23,35), ozone (5,18,22,29), chlorine dioxide (8,12,22,30,34), mixed oxidants (MIOX) (6,40), and chlorine (7,22,17). Many disinfection studies have used animal infectivity or surrogate in vitro assays to determine the viability of oocysts after disinfection.…”

Photoreactivation of Escherichia coli after Low- or Medium-Pressure UV Disinfection Determined by an Endonuclease Sensitive Site Assay

“…The ability of UV light to inactivate microorganisms (in other words, the sensitivity of microorganisms to UV light) is known to differ from organism to organism (1,14,25). Many researchers have pointed out that parasites such as Cryptosporidium and Giardia, the most problematic waterborne pathogens, can be inactivated effectively by UV irradiation (1,2,5,6,7,15). This should be a great advantage of UV disinfection systems, because such parasites are known to be highly resistant to conventional chemical disinfectants, such as chlorine.…”