Effects of ozone, chlorine dioxide, chlorine, and monochloramine on Cryptosporidium parvum oocyst viability.
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The data indicate that C. parvum oocysts are 30 times moreresistant to ozone and 14 times more resistant to chlorine dioxide than Giardia cysts exposed to these disinfectants under the same conditions.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.read more
Citations
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Drinking Water Quality, Feeding Practices, and Diarrhea among Children under 2 Years of HIV-Positive Mothers in Peri-Urban Zambia
Rachel Peletz,Michelo Simuyandi,Kelvin Sarenje,Kathy Baisley,Paul Kelly,Suzanne Filteau,Thomas Clasen +6 more
TL;DR: Children born to HIV-positive mothers in peri-urban Zambia were exposed to contaminated water through direct intake of drinking water, indicating the need for interventions to ensure microbiological water quality.
Journal ArticleDOI
Cryptosporidium in water: treatment and monitoring methods
Abstract: The problem of Cryptosporidium in water is briefly reviewed, with some mention of the effectiveness of available treatment methods. Since conventional disinfection can be much less effective than for other pathogens, it is essential to achieve very high degrees of removal by physical means. Cryptosporidium oocysts are nearly spherical, with a diameter of around 5 μm, and should be no more difficult to remove than other particles of similar properties. Nevertheless, conventional treatment such as flocculation followed by rapid filtration through granular media can allow some oocysts to pass. Specific monitoring methods for Cryptosporidium are available, but these are time-consuming and subject to some uncertainties. They are not suitable for on-line monitoring. Alternative, non-specific monitoring techniques are considered, including turbidity and particle monitoring. It is shown that particles in the oocyst size range are not sensitively detected by conventional turbidity monitoring, and that a very low treated water turbidity may not imply the absence of Cryptosporidium. Similar remarks apply to Giardia cysts. Particle counting instruments or a simpler particle monitor based on turbidity fluctuations, may provide a more reliable indication of the presence of particles a few microns in size, including Cryptosporidium and Giardia. The basic principles of these techniques are reviewed, and some results of laboratory testing and trials in water treatment plants are given Le probleme de Cryptosporidium dans l'eau est brievement passe en revue en mentionnant l'efficacite des methodes de traitement disponibles. Etant donne que la desinfection conventionnelle peut etre bien moins efficace que pour les autres pathogenes, il est essentiel de realiser de hautes valeurs d'elimination par methodes physiques. Les oocystes de Cryptosporidium sont presque spheriques, avec un diametre proche de 5 μm et ne devraient pas etre plus difficiles a eliminer que d'autres particules de proprietes similaires. Neanmoins, un traitement classique comme la floculation suivie par une filtration rapide sur media granulaire peut laisser passer quelques oocystes. Des methodes de controle specifique pour Cryptosporidium sont disponibles mais elles demandent du temps et sont sujettes a irregularites. Elles ne sont pas valables pour le controle en ligne. On considere des techniques de controle alternatives et non specifiques comme le controle de turbidite et de particules. On montre que des particules dans le domaine granulometriques des oocystes ne sont pas detectees avec sensibilite par le controle conventionnel de turbidite et qu'une turbidite tres basse de l'eau traitee n'implique pas l'absence de Cryptosporidium. Des remarques similaires s'appliquent aux cystes de Giardia. Les instruments de comptage particulaire ou un controle de particules plus simple base sur les fluctuations de la turbidite peuvent fournir une indication plus fiable de la presence de particules de quelques microns, parmi lesquelles Cryptosporidium et Giardia. Les principes de base de ces techniques sont passees en revue et l'on donne quelques resultats d'essais de laboratoire et sur unites de traitement d'eau
Journal ArticleDOI
Occurrence of Giardia and Cryptosporidium in the Kau-Ping River and its watershed in Southern Taiwan
TL;DR: The detection methods are immunofluorescence assay and enzyme-linked immunosorbent assay for water samples and fecal specimens, respectively, and Giardia was related only to Cryptosporidium but not to the others.
Journal ArticleDOI
Legionella control by chlorine dioxide in hospital water systems
Zhe Zhang,Carole McCann,Jennifer Hanrahan,Annette Jencson,Daniel Joyce,Steven Fyffe,Steve Piesczynski,Robert Hawks,Janet E. Stout,Victor L. Yu,Radisav D. Vidic +10 more
TL;DR: It is indicated that ClO2 is a promising disinfectant for controlling not only Legionella, but also other microorganisms in drinking water.
References
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Book
Standard methods for the examination of water and wastewater
TL;DR: The most widely read reference in the water industry, Water Industry Reference as discussed by the authors, is a comprehensive reference tool for water analysis methods that covers all aspects of USEPA-approved water analysis.
Journal ArticleDOI
Determination of ozone in water by the indigo method
TL;DR: In this article, the decolorization of indigo trisulfonate (600 nm, pH below 4) was used to determine the concentration of aqueous ozone in the range 0.005 −30 mg 1−1.
Journal ArticleDOI
Acute enterocolitis in a human being infected with the protozoan Cryptosporidium.
TL;DR: It is suggested, on the basis of the severity of the clinical symptoms, and on the pathological changes in the rectum, that the organism in this case is likely to have been the cause of the enterocolitis and thus to have was a pathogen rather than a commensal.
Journal ArticleDOI
Isolation of Cryptosporidium oocysts and sporozoites using discontinuous sucrose and isopycnic Percoll gradients.
TL;DR: Techniques for the large-scale isolation of Cryptosporidium oocysts and sporozoites, obtained from the feces of experimentally infected Holstein calves, were developed employing discontinuous sucrose gradients and isopycnic Percoll gradients.
Journal ArticleDOI
Large Community Outbreak of Cryptosporidiosis Due to Contamination of a Filtered Public Water Supply
Edward B. Hayes,Thomas Matte,Thomas R. O'Brien,Thomas W. McKinley,Gary S. Logsdon,Joan B. Rose,Beth L. P. Ungar,David M. Word,Margaret A. Wilson,Earl G. Long,Eugene S. Hurwitz,Dennis D. Juranek +11 more
TL;DR: Current standards for the treatment of public water supplies may not prevent the contamination of drinking water by Cryptosporidium, with consequent outbreaks of cryptosporidiosis, it is concluded.