title: Comparing the efficacy of chlorine, chlorine dioxide, and ozone in the inactivation of Cryptosporidium parvum in water from Parana State, Southern Brazil.
abstract: In the present work, assays were performed to compare the efficacy of hypochlorous acid, chlorine dioxide, and ozone in the inactivation of Cryptosporidium oocyst in public water supply from Brazilian South conditions. Experiments were carried out in samples containing 2 x 10(4) oocysts/ml of C. parvum purified from feces of experimentally contaminated calves. An in vitro excystation method was used to evaluate oocysts' viability and to determine the inactivation rates of hypochlorous acid at 2 ppm, chlorine dioxide at 1, 2, and 5 ppm, and ozone at the doses of 0.18, 0.24, 0.36, 0.48, and 1.44 mg/l. By using hypochlorous acid, the maximum inactivation rate obtained was 49.04% after 120 min. Chlorine dioxide at 5 ppm inactivated 90.56% of oocysts after 90 min of contact. Ozone was the most effective product, rendering an inactivation of 100% with the concentration of 24 mg/l. Resistance of Cryptosporidium to the usual disinfectants and the need for more effective water treatments to prevent waterborne diseases in Brazil are discussed in this manuscript.
authors.affiliation: Departamento de Patologia Básica, Setor de Ciências Biológicas, Centro Politécnico, Jardim das Américas, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors.forename: Juliana Tracz
authors.initials: JT
authors.lastname: Pereira
authors.forename: Adriana Oliveira
authors.initials: AO
authors.lastname: Costa
authors.forename: Márcia Benedita
authors.initials: MB
authors.lastname: de Oliveira Silva
authors.forename: Wagner
authors.initials: W
authors.lastname: Schuchard
authors.forename: Silvia Cristina
authors.initials: SC
authors.lastname: Osaki
authors.forename: Edilene Alcântara
authors.initials: EA
authors.lastname: de Castro
authors.forename: Rosangela Clara
authors.initials: RC
authors.lastname: Paulino
authors.forename: Vanete Thomaz
authors.initials: VT
authors.lastname: Soccol
mesh_terms: D000818:Animals; D001938:Brazil; D002713:Chlorine / Q000494:pharmacology*; D017606:Chlorine Compounds / Q000494:pharmacology*; D016785:Cryptosporidium parvum / Q000187:drug effects*; D004203:Disinfection / Q000379:methods; D006997:Hypochlorous Acid / Q000494:pharmacology*; D033661:Oocysts / Q000187:drug effects; D010087:Oxides / Q000494:pharmacology*; D010126:Ozone / Q000494:pharmacology*; D018508:Water Purification / Q000379:methods*
chemical_list: D017606:Chlorine Compounds; D010087:Oxides; D002713:Chlorine; D010126:Ozone; D006997:Hypochlorous Acid; C025109:chlorine dioxide