Usefulness of Sunlight and Artificial UV Radiation Versus Chlorine for the Inactivation of Cryptosporidium Oocysts: An in Vivo Animal Study

Abstract

BACKGROUND:Cryptosporidium is an important waterborne protozoan.AIM:The aim of this study was to investigate the effect of sunlight being the natural source of UV and artificial UV irradiation on Cryptosporidium oocysts versus the effect of chlorination, being the traditional method of water disinfection and to provide an insight into the viability and degree of infectivity of Cryptosporidium oocysts, using an animal model.METHODS:An experimental study including 300 neonatal mice was carried out to investigate the effect of artificial ultraviolet (UV) irradiation and sunlight being the natural source of UV irradiation versus chlorine, the traditionally used water disinfectant on the infectivity of Cryptosporidium oocysts present in water. For each item, nine different exposure times were investigated. Parasitological assessment (Modified Ziehl Neelsen stained stool smears) and histopathological assessment of the excised segments of the small intestine (stained by both Haematoxylin & Eosin and ZN stain) of mice were used to verify the inactivation of oocysts.RESULTS:Cryptosporidium oocysts failed to induce any noticeable infection after 4 hours of artificial UV exposure that provided a UV dose of 10mJ/cm2 and after an 8 hours exposure to sunlight, whereas they showed resistance to disinfection by chlorine.CONCLUSION:The results of the study demonstrate the important role of an 8 hours sunlight exposure of potable water in plastic bottles in achieving complete inactivation of any contaminating Cryptosporidium oocysts, thus offering an applicable, economical and convenient method for the control of cryptosporidiosis especially in developing countries.

Comparative Pathobiology of the Intestinal Protozoan Parasites Giardia lamblia, Entamoeba histolytica, and Cryptosporidium parvum

“…Since all three pathogens discussed in this review are transmitted via cysts [100], the prevention is water treatment by filtration [101] or disinfection by chlorination or radiation [102]. Moreover, person-to-person and animal-to-person transmission can be prevented by standard attention to hygiene (i.e., hand washing).…”

Existence and Removal of Rotaviruses Group A and Cryptosporidium Species in a Wastewater Treatment Plant

“…Also, the reduction of Cryptosporidium from effluents was inefficient by using chlorine disinfection and by trickling filter [11]. Moreover, UV irradiation and ultrafiltration as tertiary treatment processes were able to reduce Cryptosporidium oocysts in secondary effluents [46,47]. The importance of efficient wastewater treatment is to protect water bodies that receive the treated wastewater effluents from pathogen transmission [11].…”

Insights into Solar Disinfection Enhancements for Drinking Water Treatment Applications

“…It has been reported that these pathogens, which include many forms of protozoa (such as Cryptosporidium parvum and Acanthamoeba spp.) and bacterial spores (such as Bacillus subtilis spores) are also more likely to resist conventional disinfection processes such as chlorination and ozonation [81,82]. Although SODIS has proven its ability to inactivate or considerably reduce the viability of most important and common waterborne disease such as E. coli, total and fecal coliforms as reported in many studies, the more recalcitrant the pathogen is, the higher doses of solar radiation and longer the exposure time will be required for its inactivation.…”