Inactivation of Cryptosporidium parvum oocysts with ozone

Rennecker, Jason L.; Mariñas, Benito J.; Owens, James H.; Rice, Eugene W.

doi:10.1016/s0043-1354(99)00116-5

Cited by 176 publications

(112 citation statements)

References 12 publications

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“…Data for the analysis are listed in Tables 1 and 2 (Tables 1 and 2). Tables 1 and 2 While previous work suggests that Cryptosporidium oocyst inactivation follows a second-order kinetic model (Korich et al 1990;Rennecker et al 1999;Driedger et al 2000), the The results from this study indicate that a free chlorine Ct value of 15,300 (at pH 7.5) is needed to achieve a 3-log inactivation of C. parvum oocysts originating from a Maine outbreak and 10,400 for oocysts originating from calves in Iowa. While previous studies of C. parvum disinfection rates focused on inactivation using free chlorine, most were focused on drinking water conditions and have used excystation and/or mouse infectivity to determine oocyst Values are rounded to three significant digits.…”

Section: Calculations and Statistical Analysismentioning

confidence: 54%

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Shields

Hill

Arrowood

et al. 2008

Journal of Water and Health

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Cryptosporidium is a chlorine-resistant protozoan parasite and the etiological agent in many disinfected recreational water outbreaks. While previous studies have reported disinfection Ct values for Cryptosporidium parvum using sodium hypochlorite, these studies have employed conditions and procedures which are not ideal for establishing public health remediation recommendations for chlorinated recreational water venues. In the present study, free chlorine Ct values were measured at pH 7.5 using young oocysts (,1 month old) and tissue culture to determine oocyst viability. Two different oocyst isolates were used: one originating from Iowa and one from Maine (USA). This study determined that the Ct values for a 3-log reduction in oocyst viability were 10,400 (Iowa) and 15,300 (Maine) at pH 7.5. These Ct values are higher than the Centers for Disease Control and Prevention (USA) currently recommends (Ct ¼ 9,600) for achieving a 3.0-log inactivation of Cryptosporidium oocysts during remediation of recreational water venues following fecal diarrhea accidents.

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Section: Calculations and Statistical Analysismentioning

confidence: 54%

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Shields

Hill

Arrowood

et al. 2008

Journal of Water and Health

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“…Data from the tissue homogenates indicated that the likelihood of infecting neonatal mice was significantly lower with intact oocysts isolated after excystation protocol III (2) than the likelihood of infecting neonatal mice with intact oocysts isolated after excystation protocols I or II (3,11) (Table 3) (significant difference in the odds of mouse infection with oocysts remaining after protocol I versus protocol III, P ϭ 0.03; protocol II versus protocol III, P ϭ 0.04). In addition, the likelihood of infecting neonatal mice was significantly lower with intact oocysts isolated after excystation protocol III (2) than the likelihood of infecting neonatal mice inoculated with fresh oocysts (positive controls) (P ϭ 0.002).…”

Section: Vol 70 2004 Neonatal-mouse Infectivity Of Intact C Parvummentioning

confidence: 99%

“…We attempted to replicate the protocol described by Rennecker et al (11). The excystation medium consisted of 1.5% (wt/vol) taurocholate and 0.5% (wt/vol) trypsin dissolved in Hanks balanced salt solution (Sigma).…”

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confidence: 99%

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Neonatal-Mouse Infectivity of Intact Cryptosporidium parvum Oocysts Isolated after Optimized In Vitro Excystation

Hou

Dunbar

et al. 2004

Appl Environ Microbiol

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We reexamined the finding of Neumann et al. (10) that intact Cryptosporidium parvum oocysts obtained after in vitro excystation were infectious for neonatal CD-1 mice. We used both established excystation protocols and our own protocol that maximized excystation (2). Although intact oocysts isolated after any of three protocols were infectious for neonatal CD-1 mice, the infectivity of intact oocysts isolated with our optimized excystation protocol was significantly lower than the infectivity of intact oocysts isolated after established protocols or from fresh oocysts. Excystation should not be considered a valid measure of C. parvum viability, given that it is biologically implausible for oocysts to be nonviable and yet infectious.The use of excystation as an indicator of Cryptosporidium parvum oocyst viability has come under criticism, given the observation that intact oocysts isolated after in vitro excystation were infectious for CD-1 neonatal mice (10). The presumption is that if an oocyst cannot excyst, it will be incapable of the physical and biochemical steps involved in initiating asexual multiplication (6, 7). Using established in vitro procedures, previous studies have found a wide discrepancy in the proportion of oocysts that excyst, ranging from 50 to 95% depending on which technique was used to stimulate excystation, such as pretreatment of oocysts with acid (2, 4, 5, 10, 12). Such a wide discrepancy in excystation rates for the same batch of oocysts indicates that some excystation protocols fail to fully stimulate oocysts to excyst, resulting in excessive amounts of intact oocysts following the procedure. This result not only leads to underestimating the proportion of oocysts that are presumably viable but also biases experiments that use intact oocysts isolated after in vitro excystation.Our concern with the conclusion that intact oocysts isolated after in vitro excystation are infectious for CD-1 neonatal mice (10) is that the process of excystation appeared not to be optimized, resulting in substantial numbers of excystable (i.e., viable) oocysts failing to excyst, thereby explaining the infectious potential of such oocysts for neonatal mice. Our goal for this project was to reexamine the finding that intact C. parvum oocysts obtained after in vitro excystation were infectious for neonatal CD-1 mice, using a protocol that maximized the proportion of oocysts that excysted (2), resulting in a more valid population of intact, presumably nonviable oocysts for in vivo experimentation.C. parvum oocysts. Feces were collected from naturally infected calves at 9 to 21 days of age from three local commercial dairies in Tulare, Calif., which served as the source of wild-type C. parvum oocysts for these experiments. These oocysts were previously classified as bovine genotype A, using the genotyping scheme described by Xiao et al. (13). After an acid faststaining procedure was used to detect oocysts (9), samples having more than 25 oocysts per microscopic field (400ϫ) of fecal smears were washed through a s...

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“…While inactivation kinetics of indicator bacteria and several pathogens using ozone have received attention in scientific literature historically, little is known about the effectiveness of ozone in the destruction of bacterial and plasmid DNA [19][20][21][22][23]. Several studies have shown the efficacy of ozone disinfection through non-reversible reactions with amine groups, aromatic rings and double bonds on compound molecules like pharmaceuticals, microbial membranes and cellular contents, but these studies have given less attention to the overall destruction of chromosomal and plasmid DNA by either ozone or hydroxyl radicals in wastewater treatment plant disinfection [24,25].…”

Section: Introductionmentioning

confidence: 99%

Destruction of <i>Escherichia coli</i> and Broad-Host-Range Plasmid DNA in Treated Wastewater by Dissolved Ozone Disinfection under Laboratory and Field Conditions

Asfahl¹,

Savin²

2012

AiM

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Broad-host-range plasmids are frequently associated with antibiotic resistance genes and can quickly spread antibiotic resistant phenotypes among diverse bacterial populations. Wastewater treatment plants have been identified as reservoirs for broad-host-range plasmids carrying resistance genes. The threat of broad-host-range plasmids released into the environment from wastewater treatment plants has identified the need for disinfection protocols to target broad-hostrange plasmid destruction. Here we evaluate the efficacy of dissolved ozone at 2 and 8 mg·L -1 as a primary means for the destruction of broad-host-range plasmid and chromosomal DNA in simulated effluent. Pilot-scale tests using an experimental unit were carried out in municipal wastewater treatment plant effluent and compared with ultraviolet (UV)-irradiation and chlorination methodologies. Genes specific to Escherichia coli (uidA) and IncP broad-host-range plasmids (trfA) were monitored using real-time quantitative polymerase chain reaction (qPCR), and total DNA was monitored using absorbance spectroscopy. In wastewater treatment plant experiments, E. coli qPCR results were compared to a recognized culture-based method (Colilert ® ) for E. coli. In laboratory experiments, dissolved ozone at 8 mg·L -1 significantly destroyed 93% total, 98% E. coli, and 99% of broad-host-range plasmid DNA. Ozonation, UV-irradiation, and chlorination significantly reduced DNA concentrations and culturable E. coli in wastewater treatment plant effluent. Chlorination and UV disinfection resulted in 3-log decreases in culture-based E. coli concentrations in wastewater treatment plant effluent while changes were not significant when measured with qPCR. Only ozonation significantly decreased the IncP broad-host-range plasmid trfA gene, although concentrations of 2.2 × 10 5 copies trfA·L -1 remained in effluent. Disinfection processes utilizing high dissolved ozone concentrations for the destruction of emerging contaminants such as broad-host-range plasmid and total DNA may have utility as methods to ensure downstream environmental health and safe water reuse become more important.

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Inactivation of Cryptosporidium parvum oocysts with ozone

Cited by 176 publications

References 12 publications

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Neonatal-Mouse Infectivity of Intact Cryptosporidium parvum Oocysts Isolated after Optimized In Vitro Excystation

Destruction of <i>Escherichia coli</i> and Broad-Host-Range Plasmid DNA in Treated Wastewater by Dissolved Ozone Disinfection under Laboratory and Field Conditions

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Inactivation of Cryptosporidium parvum oocysts with ozone

Cited by 176 publications

References 12 publications

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Neonatal-Mouse Infectivity of Intact Cryptosporidium parvum Oocysts Isolated after Optimized In Vitro Excystation

Destruction of &lt;i&gt;Escherichia coli&lt;/i&gt; and Broad-Host-Range Plasmid DNA in Treated Wastewater by Dissolved Ozone Disinfection under Laboratory and Field Conditions

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Destruction of <i>Escherichia coli</i> and Broad-Host-Range Plasmid DNA in Treated Wastewater by Dissolved Ozone Disinfection under Laboratory and Field Conditions