Destruction of oocysts of Cryptosporidium parvum by sand and chlorine

Parker, J. F. W.; Smith, H. V.

doi:10.1016/0043-1354(93)90184-j

Cited by 23 publications

(17 citation statements)

References 6 publications

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“…They reported that the combination of free chlorine (1 mg/L for 60 min) and chloramines (2 mg/L for 240 min) achieved 99% inactivation of Cryptosporidium oocysts. Parker & Smith also speculated that the abrasive action on an oocyst caused by passage through a filter and subsequent chlorination may enhance oocyst inactivation (75).…”

Section: Transport and Viability Through Water Treatment Processesmentioning

confidence: 99%

ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS

Rose

1997

Annu. Rev. Public Health

197

129

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Cryptosporidium has become the most important contaminant found in drinking water and is associated with a high risk of waterborne disease particularly for the immunocompromised.There have been 12 documented waterborne outbreaks in North America since 1985; in two of these (Milwaukee and Las Vegas) mortality rates in the immunocompromised ranged from 52% to 68%.The immunofluorescence antibody assay (IFA) using epifluorescence microscopy has been used to examine the occurrence of Cryptosporidium in sewage (1 to 120 oocysts/liter), filtered secondary treated wastewater (0.01 to 0.13 oocysts/liter), surface waters (0.001 to 107 oocysts/liter), groundwater (0.004 to 0.922 oocysts/ liter) and treated drinking water (0.001 to 0.72 oocysts/liter).New rules are being developed (Information Collection Rule and Enhanced Surface Water Treatment Rule) to obtain more occurrence data for drinking water systems for use with new risk assessment models. Public health officials should consider a communication program to physicians treating the immunocompromised, nursing homes, develop a plan to evaluate cases of cryptosporidiosis in the community, and contribute to the development of public policies that limit contamination of source waters, improve water treatment, and protect public health.

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Section: Transport and Viability Through Water Treatment Processesmentioning

confidence: 99%

ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS

Rose

1997

Annu. Rev. Public Health

197

129

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“…Outside its host, C. parvum exists as a nonreproductive oocyst, ϳ5 m in diameter, that is resistant to typical environmental stresses (6,29,39,40). C. parvum oocysts originate from the waste of infected hosts and are discharged in large quantities from municipal wastewater treatment facilities, animal agriculture, and wildlife populations (2,18,26,47).…”

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confidence: 99%

Capture and Retention of Cryptosporidium parvum Oocysts by Pseudomonas aeruginosa Biofilms

Searcy

Packman

Atwill

et al. 2006

Appl Environ Microbiol

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The association of Cryptosporidium oocysts with biofilm communities can influence the propagation of this pathogen through both environmental systems and water treatment systems. We observed the capture and retention of C. parvum oocysts in Pseudomonas aeruginosa biofilms using laboratory flow cells. Biofilms were developed in two different growth media using two different strains of P. aeruginosa, a wild-type strain (PAO1) and a strain that overproduces the exopolysaccharide alginate (PDO300). Confocal laser-scanning microscopy was used in conjunction with image analysis to assess the structure of the biofilms prior to introducing oocysts into the flow cells. More oocysts were captured by the biofilm-coated surfaces than the abiotic glass surface in both media. There was no significant difference in capture across the two strains of P. aeruginosa biofilm, but the fraction of oocysts captured was positively related to biofilm roughness and surface-area-to-volume ratio. Once captured, oocysts were retained in the biofilm for more than 24 h and were not released after a 40-fold increase in the system flow rate. We believe the capture and retention of oocysts by biofilm communities can impact the environmental transmission of C. parvum, and this interaction should be taken into consideration when predicting the migration of pathogens in the environment.The human pathogen Cryptosporidium parvum is responsible for numerous waterborne disease outbreaks in the United States (15,20,34,41,43). Outside its host, C. parvum exists as a nonreproductive oocyst, ϳ5 m in diameter, that is resistant to typical environmental stresses (6,29,39,40). C. parvum oocysts originate from the waste of infected hosts and are discharged in large quantities from municipal wastewater treatment facilities, animal agriculture, and wildlife populations (2,18,26,47). Because oocysts are persistent in the environment, the transmission of viable oocysts from sources to public water supplies can result in human infection even over long transport distances. Therefore, protection of public health requires a clear understanding of the factors that control the migration of Cryptosporidium in the environment.The transport of C. parvum oocysts can be influenced by interactions with surface-attached microbial communities, generally termed biofilms. Biofilms are ubiquitous in aquatic environments, where they form on rocks, plants, and sediments, and are also prevalent in wastewater treatment systems. Biofilm microorganisms are encased in a heterogeneous matrix of extracellular polymeric substances (EPS) composed of polysaccharides, proteins, lipids, and nucleic acids (10, 16). Both the morphology and chemical characteristics of biofilms are expected to promote the deposition and retention of C. parvum oocysts. Previous studies in both laboratory and environmental systems have shown that colloidal particles such as latex beads, bacteria, and virions can be readily transferred to biofilm communities from the surrounding bulk fluid (4,13,17,32,33,37,44,45). As...

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“…Outside of its host, C. parvum exists as a nonreproductive oocyst that can persist for long periods of time in the environment because of its high degree of resistance to chemical and physical stresses (6,17,23,28). Oocysts typically enter surface water systems from the waste of infected hosts, and major sources include municipal wastewater treatment facilities and runoff from agricultural and wildlife populations (3,11,15,39).…”

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confidence: 99%

Deposition of Cryptosporidium Oocysts in Streambeds

Searcy

Packman

Atwill

et al. 2006

Appl Environ Microbiol

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The transfer of Cryptosporidium oocysts from the surface water to the sediment beds of streams and rivers influences their migration in surface waters. We used controlled laboratory flume experiments to investigate the deposition of suspended Cryptosporidium parvum oocysts in streambeds. The experimental results demonstrate that hydrodynamic interactions between an overlying flow and a sediment bed cause oocysts to accumulate in the sediments and reduce their concentrations in the surface water. The association of C. parvum with other suspended sediments increased both the oocysts' effective settling velocity and the rate at which oocysts were transferred to the sediment bed. A model for the stream-subsurface exchange of colloidal particles, including physical transport and physicochemical interactions with sediment grains, accurately represented the deposition of both free C. parvum oocysts and oocysts that were attached to suspended sediments. We believe that these pathogen-sediment interactions play an important role in regulating the concentrations of Cryptosporidium in streams and rivers and should be taken into consideration when predicting the fate of pathogens in the environment.

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Destruction of oocysts of Cryptosporidium parvum by sand and chlorine

Cited by 23 publications

References 6 publications

ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS

ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS

Capture and Retention of Cryptosporidium parvum Oocysts by Pseudomonas aeruginosa Biofilms

Deposition of Cryptosporidium Oocysts in Streambeds

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