<i>Giardia</i> Cysts in Tertiary‐Treated Wastewater Effluents: Are They Infective?

Garcia, April; Yanko, William A.; Batzer, Glenda; Widmer, Giovanni

doi:10.2175/106143002x140341

Cited by 17 publications

(14 citation statements)

References 13 publications

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“… Garcia et al (2002) reported analysis of primary effluent and reclaimed water for Giardia cysts using vital dye stains and animal infectivity. Vital dye stains provide microscopic evidence of potentially viable cysts based on the integrity of the organism's cell wall.…”

Section: Introductionmentioning

confidence: 99%

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Detection of Infectious Parasites in Reclaimed Water

Huffman¹,

Gennaccaro²,

Berg³

et al. 2006

Water Environment Research

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The presence of infectious protozoan pathogens in reclaimed water may present an unacceptable health risk. This study was designed similar to a study reported by Garcia et al. (2002), which detected no infectious Giardia cysts in the final effluent of a tertiary treatment facility as determined by animal infectivity (dose 1000 cysts/gerbil). This study also included evaluation of Cryptosporidium oocyst infectivity. Infectious Giardia cysts were detected in the final effluent with 1 gerbil out of 3 inoculated with 250 cysts from reclaimed water showing signs of infection 15 days postinoculation. None of the Cryptosporidium oocysts concentrated from the reclaimed water samples appeared to be infectious. Water Environ. Res., 78, 2297Res., 78, (2006.

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Section: Introductionmentioning

confidence: 99%

“…Vital dye stains provide microscopic evidence of potentially viable cysts based on the integrity of the organism's cell wall. While vital dye staining identified 1300 potentially viable cysts/100 L in the effluent samples, no infection was observed using gerbils for animal infectivity analysis ( Garcia et al, 2002 ).…”

Section: Introductionmentioning

confidence: 99%

Detection of Infectious Parasites in Reclaimed Water

Huffman¹,

Gennaccaro²,

Berg³

et al. 2006

Water Environment Research

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“…In comparison, Linden (2002) reported no infection of gerbils inoculated with 600 cysts exposed to a UV dose of 20 mJ/cm 2 in laboratory experiments. In another study, Garcia et al (2002) found no cysts in the faeces of gerbils inoculated with 200 cysts or 1000 cysts recovered from tertiary-treated and chlorine disinfected wastewater. Neither of these studies, however, provided details regarding the presence or absence of trophozoites in the small intestine.…”

Section: Infectivity Of G Lamblia Cysts Recovered From Wastewatermentioning

confidence: 93%

“…Studies have shown that potentially human-infective G. lamblia cysts are commonly present in raw sewage and treated wastewater in Canada (Wallis et al 1996). Wastewater treatment processes will remove or inactivate some of the parasites (Caccio et al 2003); however, a few studies have reported that cysts and oocysts detected in undisinfected wastewater effluent are viable (Garcia et al 2002;Gennaccaro et al 2003;Quintero-Betancourt et al 2003;Robertson et al 2000). The reported numbers of G. lamblia cysts present in effluents discharged from wastewater treatment facilities is often fairly high and, therefore, of potential public health concern (Casson et al 1990;Medema and Schijven 2001;Shepel 2000).…”

Section: Introductionmentioning

confidence: 99%

The Infectivity of <I>Giardia lamblia</I> Cysts in Wastewater Effluents Before and After UV treatment

Li¹,

Craik²,

Smith³

et al. 2005

proc water environ fed

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Giardia lamblia is a protozoan parasite that has been frequently associated with waterborne disease. Several waterborne Giardiasis outbreaks have been linked with discharge of wastewater effluents into surface water that serves as a source water of drinking water supply. Little is known about the infectivity of G. lamblia cysts present in UV treated wastewater effluents and the potential public health concerns. In this study, the infectivity of G. lamblia cysts recovered and concentrated from wastewater effluents both upstream and downstream of operating UV reactors in three full-scale UV reactors in Western Canada was assessed using the Mongolian gerbil model. Cysts were detected in all three wastewater effluents. Infectivity of the cysts present in the wastewater effluents was reduced by UV irradiation, but was not completely eliminated. However, only weak infections were detected in gerbils inoculated with cysts collected from both upstream and downstream of the UV reactors.

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“…Infectivity tests remain the best tool by which to define the real risk of environmental contamination by parasitic protozoa. Currently, the procedure involves incubation in an animal model and fecal analysis after the protozoal life cycle has been completed, to estimate the level of infectivity . However, this procedure is very expensive and may take a long time to give conclusive data.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence decay of dyed protozoa: differences between stressed and non‐stressed cysts

et al. 2015

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Several series of tests have shown that fresh, intact samples of Giardia duodenalis and Cryptosporidium parvum (oo)cysts are not marked by fluorescent probes such as carboxyfluorcein-succinimidyl-diacetate-ester (CFDA-SE), C12-resazurin and SYTOX® Green, probably because of their robust cell walls. These dyes fail to indicate the viability of such protozoa and allow negative responses to be recorded from living and infectious samples. Cryptosporidium parvum showed stronger isolation from chemicals, with living oocysts remaining unstained by the probe for up to 90 days after extraction. However, in further fluorescence decay (FD) experiments run with G. duodenalis samples stained using CFDA-SE (comprising living, non-stressed but aged cysts, heat-killed samples and UV-C-stressed samples) each showed a different FD decay profile, here studied in seven series of tests of five replicates each. The FD profiles were fitted by double-exponential decay kinetics, with the decay constant k2 being five times higher than k1. This FD procedure is fast and can be easily reproduced in 10 steps, taking ~ 1 h of laboratory work for already purified samples.

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Giardia Cysts in Tertiary‐Treated Wastewater Effluents: Are They Infective?

Cited by 17 publications

References 13 publications

Detection of Infectious Parasites in Reclaimed Water

Detection of Infectious Parasites in Reclaimed Water

The Infectivity of <I>Giardia lamblia</I> Cysts in Wastewater Effluents Before and After UV treatment

Fluorescence decay of dyed protozoa: differences between stressed and non‐stressed cysts

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