Predation of Cryptosporidium oocysts by protozoa and rotifers: implications for water quality and public health

2003 ◽  
Vol 47 (3) ◽  
pp. 77-83 ◽  
Author(s):  
R. Stott ◽  
E. May ◽  
E. Ramirez ◽  
A. Warren
Keyword(s):  
Aquatic Ecosystems ◽  
Wastewater Treatment Plants ◽  
Ciliated Protozoa ◽  
Free Living ◽  
Predator Species ◽  
Cryptosporidium Oocysts ◽  
Cryptosporidium Parvum Oocysts ◽  
Acanthamoeba Culbertsoni ◽  
Dose Levels ◽  
Stylonychia Mytilus

Predation by free-living protozoa and rotifers was investigated as a possible mechanism for the removal of Cryptosporidium parvum oocysts in aquatic ecosystems including wastewater treatment plants. Free-living ciliated protozoa (Stylonychia mytilus, Paramecium caudatum and an unidentified wastewater wetland ciliate), an amoeba (Acanthamoeba culbertsoni) and rotifers, all commonly found in aquatic ecosystems, were exposed to varying doses of C. parvum oocysts. All organisms investigated ingested oocysts. Predation activity and rates of ingestion varied with predator species and prey density. Ciliated protozoa demonstrated greater predation activity than A. culbertsoni or rotifers when exposed to 2 × 105 oocyst/mL for up to 3 h. Greatest predation after 1 h exposure was observed in P. caudatum, the largest ciliate, with on average 1.9 oocysts/cell (range 0-9 oocysts/cell). Stylonychia mytilus and the wetland ciliate had a similar mean ingestion of around 0.3 oocysts/cell, with numbers internalised ranging from 0-3 oocysts/cell. Rotifers ingested on average 1.6 oocysts/individual (range 0-7 oocysts/individual) whilst amoebae ingested on average 1.8 oocysts/cell after 2 h exposure (up to 3 oocysts/cell). Grazing activity by P. caudatum was demonstrated at a variety of prey levels ranging from 9 to 9,000 oocysts. Numbers of oocysts internalised by Paramecium frequently exceeded the reported human infective dose of 30 oocysts. In general, numbers of internalised oocysts increased with incubation time of up to 20-30 min although the rate of accumulation was slower at lower dose levels. The significance of predation on the fate of Cryptosporidium oocysts in the environment is discussed.

Protozoan predation as a mechanism for the removal of cryptosporidium oocysts from wastewaters in constructed wetlands

2001 ◽  
Vol 44 (11-12) ◽  
pp. 191-198 ◽  
Author(s):  
R. Stott ◽  
E. May ◽  
E. Matsushita ◽  
A. Warren
Keyword(s):  
Constructed Wetlands ◽  
Protozoan Parasite ◽  
Epifluorescence Microscopy ◽  
Free Living ◽  
Feeding Experiments ◽  
Treatment Processes ◽  
Ciliate Species ◽  
Cryptosporidium Oocysts ◽  
The Uk ◽  
Stylonychia Mytilus

The removal of the protozoan parasite, Cryptosporidium parvum, from wastewaters is becoming of increasing importance in the UK, especially since contamination of raw waters by sewage effluents has been implicated in major waterborne outbreaks of cryptosporidiosis in recent years. Compared to conventional wastewater-treatment processes, constructed wetlands have demonstrated favourable removal rates for Cryptosporidium oocysts. The removal mechanisms, however, remain unknown. Predation by free-living ciliated protozoa, which are commonly found in constructed wetlands, was investigated as a possible mechanism for oocyst removal. In laboratory feeding experiments, ciliates (Euplotes patella, Stylonychia mytilus, Paramecium caudatum and an unidentified wetland ciliate species), were exposed to doses ranging from 10 to 106 oocysts/ml for between 5 and 60 minutes. Ciliate predatory activities were assessed by enumerating fluorescently labelled ingested oocysts using epifluorescence microscopy. Oocysts were found to be ingested by all species investigated. Paramecium demonstrated the highest mean ingestion rates (up to 170 oocysts/hr) followed by Stylonychia (up to 60 oocysts/hour). Euplotes and the wetland ciliate had lower mean grazing rates (4 and 10 oocysts/hr respectively). These results indicate that protozoan predation may be an important factor in the removal of Cryptosporidium oocysts from wastewaters in constructed wetlands.

Occurrence and persistence of bacterial and viral faecal indicators in wastewater biofilms

2007 ◽  
Vol 55 (8-9) ◽  
pp. 377-385 ◽  
Author(s):  
S. Skraber ◽  
K. Helmi ◽  
R. Willame ◽  
M. Ferréol ◽  
C. Gantzer ◽  
...  
Keyword(s):  
Dynamic Equilibrium ◽  
Wastewater Treatment Plants ◽  
Plate Count ◽  
Cryptosporidium Oocysts ◽  
The Matrix ◽  
Thermotolerant Coliforms ◽  
Viral Indicators ◽  
The Stability ◽  
Faecal Indicators ◽  
Giardia Cysts

Biofilms within wastewater treatment plants can capture enteric microorganisms initially present in the water phase immobilising them either definitively or temporarily. Consequently, fates of microorganisms may totally change depending on whether they interact or not with biofilms. In this study, we assessed the stability of wastewater biofilms comparing the evolution of the concentrations of bacteria (heterotrophic plate count [HPC], thermotolerant coliforms [TC]) and viral (somatic coliphages [SC] and F-specific phages [F+]) indicators in the biofilms and in the corresponding wastewaters at 4 and 20 °C. Additionally, we assessed the monthly occurrence of these bacterial and viral indicators as well as of pathogenic protozoa (Cryptosporidium oocysts and Giardia cysts) in three native wastewater biofilms for four months. Our results show that viral indicators (SC and F+) persist longer in biofilms than in the corresponding wastewaters at 4 °C as well as at 20 °C. In contrast, persistence of bacterial indicators (TC and HPC) depends on both the temperature and the matrix. Differences between viral and bacterial persistence are discussed. Monthly analysis of native wastewater biofilms shows that bacterial and viral indicators, as well as Cryptosporidium oocysts and Giardia cysts, attach to wastewater biofilms to a concentration that remains stable in time, probably as a result of a dynamic equilibrium between attachment and detachment processes.

Microwave Inactivation of Cyclospora cayetanensis Sporulation and Viability of Cryptosporidium parvum Oocysts

2006 ◽  
Vol 69 (8) ◽  
pp. 1957-1960 ◽  
Author(s):  
YNES R. ORTEGA ◽  
JYEYIN LIAO
Keyword(s):  
Cryptosporidium Parvum ◽  
Propidium Iodide ◽  
Cryptosporidium Oocyst ◽  
Cooking Time ◽  
Cyclospora Cayetanensis ◽  
The Third ◽  
Infectivity Assay ◽  
Cryptosporidium Oocysts ◽  
Cryptosporidium Parvum Oocysts ◽  
Cooking Times

The efficacy of microwave heating on the viability of Cryptosporidium parvum oocysts and on the sporulation of Cyclospora cayetanensis oocysts for various periods of cooking times (0, 10, 15, 20, 30, and 45 s) at 100% power was determined. Cyclospora oocysts were stored in 2.5% dichromate at 23°C for 2 weeks, and sporulation rates were then determined. The 4′,6-diamidino-2-phenylindole and propidium iodide vital stain and the neonate animal infectivity assay determined Cryptosporidium oocyst viability. Cryptosporidium oocysts could be completely inactivated with as little as 20 s of cooking time, whereas Cyclospora sporulation was observed up to 45 s. Two of the examined microwave ovens were more effective at reducing sporulation and viability than the third one. Because of the variability of temperature achieved by the various ovens, cooking time was not an accurate parameter for parasite inactivation. Cryptosporidium oocysts could be inactivated only when temperatures of 80°C or higher were reached in the microwave ovens.

Influence of US EPA 1622 method successive steps on the viability of Cryptosporidium oocysts

2000 ◽  
Vol 41 (7) ◽  
pp. 189-196 ◽  
Author(s):  
K. Guyot ◽  
M. F. Gireaudot-Liepmann ◽  
A. Cabon ◽  
I. Riveau-Ricard ◽  
M. Lange ◽  
...  
Keyword(s):  
Water Samples ◽  
Tap Water ◽  
High Recovery ◽  
The Us ◽  
Cryptosporidium Oocysts ◽  
Cartridge Filter ◽  
Us Epa ◽  
Cryptosporidium Parvum Oocysts ◽  
Elution Step

Viable Cryptosporidium parvum oocysts were processed by the US EPA 1622 method to determine if the procedure that requires successive filtration, elutionand centrifugation alters their integrity and viability (determined by in vitro excystation). Oocyst seeded in tap water samples were also used to evaluate recovery efficiencies and impact of the whole procedure on oocyst viability. Filtration through Envirochek Gelman cartridge was found not to damage oocysts. The use of Laureth-12 buffer during the elution step was shown to lead to greater spontaneous oocysts excystation than other phosphate buffers containing between 80 and/or SDS (like the Gelman buffer). However, this drawback was widely balanced against the best efficiency of this buffer to elute oocysts captured by the cartridge filter and therefore against its high recovery efficiency. Thus, in water samples in which the oocyst concentration is expected to be low, it is more advantageous to employ the Laureth-12 buffer for the elution through it can influence viability. Centrifugation speeds (1,000–5,000 g) did not alter oocysts.

Identification of pathogen bacteria and protozoa in treated urban wastewaters discharged in the Ebro River (Spain): water reuse possibilities

2013 ◽  
Vol 68 (3) ◽  
pp. 575-583 ◽  
Author(s):  
R. Mosteo ◽  
M. P. Ormad ◽  
P. Goñi ◽  
J. Rodríguez-Chueca ◽  
A. García ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Water Reuse ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Research Work ◽  
Municipal Wastewater Treatment ◽  
Tertiary Treatment ◽  
Salmonella Spp ◽  
Free Living ◽  
Municipal Wastewater Treatment Plants

The aim of this research work is to identify the presence of pathogens, bacteria and protozoa, in different treated urban wastewaters and to relate biological pollution with the processes used in wastewater treatment plants. A study of the possibilities for water reuse is carried out taking into account bacterial and parasite composition. The analysed bacteria and protozoa are: Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Clostridium perfringens (spore), Salmonella spp., Legionella spp., helminths eggs, Giardia, Cryptosporidium spp. and free-living amoebae (FLA). The selected municipal wastewater treatment plants (MWTPs) are located in Navarra (Spain) and the main difference between them is the use of natural lagoons as tertiary treatment in some plants. The results concerning bacteriological identification showed contamination of mainly faecal origin, and the use of natural lagoons as tertiary treatment in some MWTPs produced an important disinfection effect. Moreover, pathogen parasites such as Giardia and Cryptosporidium were not detected in the samples studied although FLA were identified in all cases.

Potentially pathogenic free-living amoebae (FLA) isolated in Spanish wastewater treatment plants

2011 ◽  
Vol 3 (5) ◽  
pp. 622-626 ◽  
Author(s):  
A. García ◽  
P. Goñi ◽  
A. Clavel ◽  
S. Lobez ◽  
M. T. Fernandez ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Free Living

scholarly journals Field scale quantification of microbial transport from bovine faeces under simulated rainfall events

2006 ◽  
Vol 5 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Christobel M. Ferguson ◽  
Cheryl M. Davies ◽  
Christine Kaucner ◽  
Nicholas J. Ashbolt ◽  
Martin Krogh ◽  
...  
Keyword(s):  
Cryptosporidium Oocyst ◽  
Experimental Treatment ◽  
Bare Soil ◽  
Simulated Rainfall ◽  
Rainfall Events ◽  
E Coli ◽  
Artificial Rainfall ◽  
Cryptosporidium Oocysts ◽  
Cryptosporidium Parvum Oocysts ◽  
Experimental Soil

The dispersion and transport of Cryptosporidium parvum oocysts, Escherichia coli and PRD1 bacteriophage seeded into artificial bovine faecal pats was studied during simulated rainfall events. Experimental soil plots were divided in two, one sub-plot with bare soil and the other with natural vegetation. Simulated rainfall events of 55 mm.h-1 for 30 min were then applied to the soil plots. Each experimental treatment was performed in duplicate and consisted of three sequential artificial rainfall events (‘Runs’): a control run (no faecal pats); a fresh faecal pat run (fresh faecal pats); and an aged faecal pat run (one week aged faecal pats). Transportation efficiency increased with decreasing size of the microorganism studied; Cryptosporidium oocysts were the least mobile followed by E. coli and then PRD1 phage. Rainfall events mobilised 0.5 to 0.9% of the Cryptosporidium oocysts, 1.3‒1.4% of E. coli bacteria, and 0.03‒0.6% of PRD1 bacteriophages from the fresh faecal pats and transported them a distance of 10 m across the bare soil sub-plots. Subsequent rainfall events applied to aged faecal pats only mobilised 0.01‒0.06% of the original Cryptosporidium oocyst load, between 0.04 and 15% of the E. coli load and 0.0006‒0.06% of PRD1 bacteriophages, respectively.

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