Batch solar disinfection inactivates oocysts of Cryptosporidium parvum and cysts of Giardia muris in drinking water

Abstract

Aim: To determine whether batch solar disinfection (SODIS) can be used to inactivate oocysts of Cryptosporidium parvum and cysts of Giardia muris in experimentally contaminated water. Methods and Results: Suspensions of oocysts and cysts were exposed to simulated global solar irradiation of 830 W m−2 for different exposure times at a constant temperature of 40°C. Infectivity tests were carried out using CD‐1 suckling mice in the Cryptosporidium experiments and newly weaned CD‐1 mice in the Giardia experiments. Exposure times of ≥10 h (total optical dose c. 30 kJ) rendered C. parvum oocysts noninfective. Giardia muris cysts were rendered completely noninfective within 4 h (total optical dose >12 kJ). Scanning electron microscopy and viability (4′,6‐diamidino‐2‐phenylindole/propidium iodide fluorogenic dyes and excystation) studies on oocysts of C. parvum suggest that inactivation is caused by damage to the oocyst wall. Conclusions: Results show that cysts of G. muris and oocysts of C. parvum are rendered completely noninfective after batch SODIS exposures of 4 and 10 h (respectively) and is also likely to be effective against waterborne cysts of Giardia lamblia. Significance and Impact of the Study: These results demonstrate that SODIS is an appropriate household water treatment technology for use as an emergency intervention in aftermath of natural or man‐made disasters against not only bacterial but also protozoan pathogens.

Establishing Solar Water Disinfection as a water treatment method at household level

“…During the exposition, the sunlight destroys the pathogenic bacteria, viruses as well as Cryptosporidium spp. and Giardia spp (Wegelin et al 1994;Mendez-Hermida et al 2005;McGuigan et al 2006). The destruction of parasites is caused by the UV-A radiation of the sunlight.…”

Drinking Water Disinfection by Solar Radiation

“…Most of these pathogenic protozoa can be destroyed in water samples that are continuously exposed to sunlight for 7 hours and kept at [50][51][52][53][54][55][56][57][58][59][60] o C in 2 liter one side blackened bottles [52,53]. Cryptosporidium parvum oocyst viability can be reduced by 86.3% and 97.7% during 8 h and 12 h strong solar exposure [14,54]. It should be noted that the cumulative dose as well as the way of dosing (continuously, intermittently, average radiation, as direct or diffuse UV) significantly affects the observed behavior of inactivation [55,56].…”

“…[14,51,52]. Most of these pathogenic protozoa can be destroyed in water samples that are continuously exposed to sunlight for 7 hours and kept at [50][51][52][53][54][55][56][57][58][59][60] o C in 2 liter one side blackened bottles [52,53].…”

“…Solar radiation removes a broad range of microorganisms such as viruses, bacteria and protozoa [14]. Contaminated drinking water in the transparent carriers such as plastic bottles, bags and glass bottles are placed in direct sunlight for at least 6 hours prior to consumption [14][15][16]. Destruction of microorganisms during solar disinfection is achieved by the synergistic effects of mild heat and UV radiation, leading to pasteurization and UV disinfection [17].…”

“…It has been demonstrated that solar disinfection inactivates microorganism by direct exposure is volume independent economic process and avoids production of hazardous by-products of chemically driven technologies [13]. Solar radiation removes a broad range of microorganisms such as viruses, bacteria and protozoa [14]. Contaminated drinking water in the transparent carriers such as plastic bottles, bags and glass bottles are placed in direct sunlight for at least 6 hours prior to consumption [14][15][16].…”