Effects of ozone, chlorine dioxide, chlorine, and monochloramine on Cryptosporidium parvum oocyst viability

Abstract

Purified Cryptosporidium parvum oocysts were exposed to ozone, chlorine dioxide, chlorine, and monochloramine. Excystation and mouse infectivity were comparatively evaluated to assess oocyst viability. Ozone and chlorine dioxide more effectively inactivated oocysts than chlorine and monochloramine did. Greater than 90% inactivation as measured by infectivity was achieved by treating oocysts with 1 ppm of ozone (1 mg/liter) for 5 min. Exposure to 1.3 ppm of chlorine dioxide yielded 90% inactivation after 1 h, while 80 ppm of chlorine and 80 ppm of monochloramine required approximately 90 min for 90% inactivation. The data indicate that C. parvum oocysts are 30 times more resistant to ozone and 14 times more resistant to chlorine dioxide than Giardia cysts exposed to these disinfectants under the same conditions. With the possible exception of ozone, the use of disinfectants alone should not be expected to inactivate C. parvum oocysts in drinking water.

Broad-spectrum bioactivities of silver nanoparticles: the emerging trends and future prospects

“…Oocyst-producing water-borne intestinal protozoa, such as Giardia lamblia and especially Cryptosporidium parvum, are resistant to traditional deactivation procedures including sizeexclusion filters and chlorine treatments (Korich et al 1990). Both the pathogens cause gastrointestinal infections throughout the world.…”

Association between management practices and within-herd prevalence of Cryptosporidium parvum shedding on dairy farms in southern Ontario

“…In 2003, a within-herd prevalence of 35% to 100% was found in a sample of calves under 1 month old on 11 dairy herds in the same region (Trotz-Williams et al, submitted for publication). Most chemotherapeutic agents and disinfectants are ineffective against this parasite (Korich et al, 1990;Weir et al, 2002). Prevention of infection is, therefore, the most viable option for reducing the incidence and impact of infection in dairy calves.…”

An immunomagnetic separation–reverse transcription polymerase chain reaction (IMS‐RT‐PCR) test for sensitive and rapid detection of viable waterborne Cryptosporidium parvum

“…It is transmitted by the faecal-oral route and causes gastrointestinal illness in humans even at low concentrations, particularly in immunologically compromised individuals (Current and Garcia, 1991). The parasite can be transmitted through water in an oocyst form that is highly resistant to conventional disinfection treatments (Korich et al ., 1990). Immunofluorescence assay (IFA) followed by microscopic examination has been the traditional method used for detecting Cryptosporidium in environmental water samples (Anonymous, 1999).…”