Drying of Cryptosporidium oocysts and Giardia cysts to slides abrogates use of vital dyes for viability staining

The aim of this study was to assess the impact of a municipal wastewater treatment plant (MWTP) on the occurrence of Cryptosporidium oocysts and Giardia cysts in the receiving water. All MWTP effluent samples were Giardia and Cryptosporidium contaminated, although low mean values were found for both parasites (0.21±0.06 oocysts/L; 1.39±0.51 cysts/L). Otherwise, in the raw sewage a greater concentration was detected (4.5±0.3 oocysts/L; 53.6±6.8 cysts/L). The major occurrence of Giardia over Cryptosporidium, both in the influent and in the effluent of the MWTP, is probably related to the human sewage contribution to the wastewater. Data on protozoa contamination of the receiving water body demonstrated similar concentrations in the samples collected before (0.21±0.07 oocysts/L; 1.31±0.38 cysts/L) and after (0.17±0.09 oocysts/L and 1.01±1.05 cysts/L) the plant effluent discharge. The results of this study suggest that the MWTP has no impact related to Giardia and Cryptosporidium river water contamination, and underline the need for investigation into the effectiveness of these protozoa removal by less technologically advanced MWTPs which are the most widespread and could probably show a lower ability to reduce protozoa.

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

Water Science & Technology ◽

10.2166/wst.2007.280 ◽

2007 ◽

Vol 55 (8-9) ◽

pp. 377-385 ◽

Cited By ~ 13

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.

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Detection of Giardia Cysts and Cryptosporidium Oocysts in Edible Shellfish: Choosing a Target

10.1007/978-1-0716-1932-2_17 ◽

2021 ◽

pp. 187-198

Author(s):

Diego Averaldo Guiguet Leal ◽

Taís Rondello Bonatti ◽

Roberta de Lima ◽

Rodrigo Labello Barbosa ◽

Regina Maura Bueno Franco

Keyword(s):

Cryptosporidium Oocysts ◽

Giardia Cysts

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Occurrence of Cryptosporidium oocysts and Giardia cysts in a conventional water purification plant

Water Science & Technology ◽

10.2166/wst.2001.0717 ◽

2001 ◽

Vol 43 (12) ◽

pp. 89-92 ◽

Cited By ~ 17

Author(s):

A. Hashimoto ◽

T. Hirata ◽

S. Kunikane

Keyword(s):

Water Purification ◽

Water Samples ◽

Geometric Mean ◽

Giardia Cyst ◽

Raw Water ◽

Observation Level ◽

Cryptosporidium Oocysts ◽

Purification Plant ◽

Mean Concentration ◽

Giardia Cysts

A one-year monitoring of Cryptosporidium oocysts and Giardia cysts was conducted at a water purification plant. A total of thirteen 50 L samples of river source water and twenty-six 2,000 L samples of filtered water (treated by coagulation-flocculation, sedimentation and rapid filtration) were concentrated using a hollow fibre ultrafiltration membrane module at a purification plant. Cryptosporidium oocysts were detected in all raw water samples with a geometric mean concentration of 400 oocysts/m3 (range 160-1,500 oocysts/m3). Giardia cysts were detected in 12/13 raw waters (92%) with a geometric mean concentration of 170 cysts/m3 (range 40-580 oocysts/m3). Probability distributions of both Cryptosporidium oocyst and Giardia cyst concentration in raw water were nearly log-normal. In filtered water samples, Cryptosporidium oocysts were detected in 9/26 samples (35%) with a geometric mean concentration of 1.2 oocysts/m3 (range 0.5-8 oocysts/m3) and Giardia cysts in three samples (12%) with 0.8 cysts/m3 (range 0.5-2 oocysts/m3). The estimated removal of Cryptosporidium oocysts and Giardia cysts was, respectively, 2.54 log10 and 2.53 log10 on the basis of geometric means, 3.20 and 3.57 log10 on the basis of 50% observation level and 2.70 and 2.90 log10 on the basis of 90% observation level.

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Occurrence of Giardia cysts and Cryptosporidium oocysts in activated sludge samples in Campinas, SP, Brazil

Revista do Instituto de Medicina Tropical de São Paulo ◽

10.1590/s0036-46652004000600003 ◽

2004 ◽

Vol 46 (6) ◽

pp. 309-313 ◽

Cited By ~ 18

Author(s):

Luciana Urbano Santos ◽

Taís Rondello Bonatti ◽

Romeu Cantusio Neto ◽

Regina Maura Bueno Franco

Keyword(s):

Activated Sludge ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

High Concentration ◽

Potential Source ◽

Two Samples ◽

Cryptosporidium Oocysts ◽

Flotation Method ◽

Giardia Cysts

Giardia and Cryptosporidium have caused several outbreaks of gastroenteritis in humans associated with drinking water. Contaminated sewage effluents are recognized as a potential source of waterborne protozoa. Due to the lack of studies about the occurrence of these parasites in sewage samples in Brazil, we compared the efficiency of two procedures for concentrating cysts and oocysts in activated sludge samples of one sewage treatment plant. For this, the samples were submitted to i) concentration by the ether clarification procedure (ECP) and to ii) purification by sucrose flotation method (SFM) and aliquots of the pellets were examined by immunofluorescence. Giardia cysts were present in all samples (100.0%; n = 8) when using ECP and kit 1 reagents, while kit 2 resulted in six positive samples (85.7%; n = 7). As for SFM, cysts were detected in 75.0% and 100.0% of these samples (for kit 1 and 2, respectively). Regarding Cryptosporidium, two samples (25.0%; kit 1 and 28.5% for kit 2) were detected positive by using ECP, while for SFM, only one sample (examined by kit 1) was positive (12.5%). The results of the control trial revealed Giardia and Cryptosporidium recovery efficiency rates for ECP of 54.5% and 9.6%, while SFM was 10.5% and 3.2%, respectively. Considering the high concentration detected, a previous evaluation of the activated sludge before its application in agriculture is recommended and with some improvement, ECP would be an appropriate simple technique for protozoa detection in sewage samples.

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