The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Elvira Aresmazas - One of the best experts on this subject based on the ideXlab platform.
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Giardia in shellfish farming areas detection in mussels river water and waste waters
Veterinary Parasitology, 2005Co-Authors: Hipolito Gomezcouso, Fernando Mendezhermida, J A Castrohermida, Elvira AresmazasAbstract:Abstract Giardia Cyst contamination of mussels (Mytilus galloprovincialis), raw and treated waste waters and water from rivers that flow into four Galician estuaries (NW Spain), where bivalve molluscs are cultured for human consumption, was studied. The high prevalence of contamination in mussels (41.8%, n = 184), raw waste water (90.9%, n = 11), treated waste water (87.5%, n = 16) and in samples of river water (85.7%, n = 7), with Cyst counts of 9.8–1800.0, 7.0–2541.0 and 1.0–29.3 Cysts l−1, respectively, illustrate the wide distribution of this enteropathogen in the environment and the potential risk to public health associated with the consumption of raw or undercooking bivalves and use of these estuaries for recreational purposes.
Lucy J Robertson - One of the best experts on this subject based on the ideXlab platform.
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Giardia Cysts in sewage influent in Bergen, Norway 15-23 months after an extensive waterborne outbreak of Giardiasis.
Journal of applied microbiology, 2007Co-Authors: Lucy J Robertson, Torunn Forberg, Bjørn GjerdeAbstract:Aims: In autumn/winter 2004, a large outbreak of waterborne Giardiasis occurred in Bergen, Norway. Over 1 year later, the concentrations and genotypes of Giardia Cysts occurring in sewage influent were studied to investigate the impact of the outbreak event on Giardia infections in the community. Methods and Results: Sewage influent samples from four sewage treatment works (STW) serving Bergen were analysed for Giardia Cysts on four occasions between 15 and 23 months after the outbreak. Cysts genotypes were investigated at one to three genes. Data from influent analysis from one of the STW before the outbreak, and from patient faecal samples analysed during the outbreak, provided baseline comparative data. Relatively high concentrations of Giardia Cysts of diverse genotypes, both from Assemblages A and B, were detected at all STW. Conclusions: Comparison of data suggests that although Giardia Cyst concentrations in sewage influent returned to pre-outbreak levels within 18 months after the outbreak peak, the genetic composition of the isolates remained significantly influenced by the Assemblage B isolate associated with the outbreak. Significance and Impact of the Study: Genotypes associated with an extensive outbreak of Giardiasis continued to occur in Giardia infections in Bergen’s population many months after the outbreak was considered to be over.
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Giardia Cysts and Cryptosporidium ooCysts at sewage treatment works in Scotland, UK
Water Research, 2000Co-Authors: Lucy J Robertson, C.a. Paton, A.t Campbell, Paul G. Smith, M. H. Jackson, R.a Gilmour, S.e Black, D.a Stevenson, Huw V. SmithAbstract:Abstract A three year study on Cryptosporidium ooCysts and Giardia Cysts in sewage was conducted with emphasis upon: (1) development and assessment of techniques for sampling and processing sewage for these parasites; (2) a field study in which six sewage treatment works (STW) were assessed for removal of these parasites from the liquid phase; and (3) assessment of effect of sewage treatment on survival/destruction of Cryptosporidium ooCysts. In sampling, grab samples were superior to filtered samples. In concentration and clarification of samples, the most efficient technique was that in which sample manipulation was minimised. Although calculated parasite removal efficiency varied for both parasites and between and within STW, some consistent patterns were observed. First, Giardia Cyst removal was significantly greater than Cryptosporidium ooCyst removal. Second, most parasite removal occurred during secondary treatments, rather than during primary settlement. Third, no significant difference between efficacy of activated sludge treatment and trickling filters at parasite removal was detected. Also, in one STW which utilised tertiary sewage treatment, most removal from the liquid phase occurred during preceding treatment stages. Finally, one STW had significantly higher removal efficiencies of both parasites than the other five STW investigated. Low numbers of viable ooCysts were detected at both influent and effluent. Survival was monitored by introducing ooCysts, in containers bounded by semi-permeable membranes, into various environments within one STW. The results demonstrated that, over one week, none of the environments tested had a deleterious effect on ooCyst viability, with the exception of the sludge-holding tank. Results are discussed in relation to other published work on Cryptosporidium and Giardia in sewage and recommendations for further areas of research on this subject are made.
Hipolito Gomezcouso - One of the best experts on this subject based on the ideXlab platform.
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Giardia in shellfish farming areas detection in mussels river water and waste waters
Veterinary Parasitology, 2005Co-Authors: Hipolito Gomezcouso, Fernando Mendezhermida, J A Castrohermida, Elvira AresmazasAbstract:Abstract Giardia Cyst contamination of mussels (Mytilus galloprovincialis), raw and treated waste waters and water from rivers that flow into four Galician estuaries (NW Spain), where bivalve molluscs are cultured for human consumption, was studied. The high prevalence of contamination in mussels (41.8%, n = 184), raw waste water (90.9%, n = 11), treated waste water (87.5%, n = 16) and in samples of river water (85.7%, n = 7), with Cyst counts of 9.8–1800.0, 7.0–2541.0 and 1.0–29.3 Cysts l−1, respectively, illustrate the wide distribution of this enteropathogen in the environment and the potential risk to public health associated with the consumption of raw or undercooking bivalves and use of these estuaries for recreational purposes.
Foppe B. Dewalle - One of the best experts on this subject based on the ideXlab platform.
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Watershed use and Giardia Cyst presence
Water Research, 1995Co-Authors: Jerry E. Ongerth, G D Hunter, Foppe B. DewalleAbstract:Abstract The presence of Giardia in a heavily visited watershed in the Olympic Mountains was compared to that in an adjacent watershed having much lower human use. Also, statistical relationships between Cyst presence and watershed use parameters were examined as indicators of potential causal relationships. The number of Giardia Cysts found in water samples ranged from 0.2 100 l to 3 100 l and were highest in areas of high human use. A significantly higher prevalence of Giardia in selected animal species was observed in the heavily visited watershed. Statistically significant relationships were found between aqueous Giardia Cyst concentrations and both the prevalence of Giardia in animals and the intensity of human use. Based on the water samples analyzed, a calculated median Cyst concentration of 1 Cyst per 20 l (0.05 Cysts/l) can be expected in relatively pristine rivers.
Edward L. Jarroll - One of the best experts on this subject based on the ideXlab platform.
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Cyst wall synthase n acetylgalactosaminyltransferase activity is induced to form the novel n acetylgalactosamine polysaccharide in the Giardia Cyst wall
Microbiology, 2004Co-Authors: Craig D Karr, Edward L. JarrollAbstract:Uridine-5′-diphospho-N-acetylgalactosamine (UDP-GalNAc) is required in the formation of the outer filamentous wall of Giardia and is synthesized by inducible enzymes in the cytosol of enCysting trophozoites. In this study, an inducible enzyme activity that is associated with a particle population isolated from enCysting Giardia is reported, and this activity exclusively incorporates [1-14C]GalNAc (from UDP-[14C]GalNAc) into an ethanol precipitate with the same properties as the filamentous Cyst wall of Giardia. This ethanol precipitate exhibits characteristics of Giardia Cyst wall filaments in that both contain GalNAc as the only sugar moieties and are SDS-insoluble, proteinase- and alkali-resistant and acid-hydrolysable. However, since the precise chemical nature of the ethanol precipitate remains unknown, this enzyme activity is referred to tentatively as Cyst wall synthase (CWS). CWS activity peaks in cells between 24 and 36 h of enCystment and exhibits a high affinity and marked specificity for UDP-GalNAc as its substrate. UDP-N-acetylglucosamine, UDP-glucose, UDP-galactose, d-glucosamine and d-galactosamine were not incorporated into the ethanol precipitate. Partially purified CWS activity exhibits an apparent K m of 0·048 mM for UDP-GalNAc, a V max of 0·70 nmol min−1 (mg protein)−1 and a requirement for divalent cations in the following order of preference: Ca2+, Mg2+>Co2+>>>Mn2+, Zn2+. EDTA inhibits CWS activity.
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the Giardia intestinalis filamentous Cyst wall contains a novel β 1 3 n acetyl d galactosamine polymer a structural and conformational study
Glycobiology, 2002Co-Authors: Gerrit J Gerwig, Craig D Karr, Albert J Van Kuik, Bas R Leeflang, Johannis P Kamerling, Johannes F G Vliegenthart, Edward L. JarrollAbstract:Assembly of a protective Cyst wall by Giardia is essential for the survival of the parasite outside the host intestine and for transmission among susceptible hosts. The structure of the G. intestinalis filamentous Cyst wall was studied by chemical methods, mass spectrometry, and (1)H nuclear magnetic resonance spectroscopy. Isolated Cyst wall material contains carbohydrate and protein in a ratio of 3:2 (w/w), and the carbohydrate moiety is composed of a beta(1-3)-N-acetyl-D-galactopyranosamine homopolymer. Conformational analysis by molecular dynamics and persistence length calculations of GalNAc oligomers in solution demonstrated a flexible structure consisting of left- and right-handed helical elements. It is most likely that in the solid state, the polysaccharide forms ordered helices or possibly multiple helical structures having strong interchain interactions. The highly insoluble nature of the Giardia Cyst wall must be due to these strong interchain interactions and, probably, a strong association between the carbohydrate and the protein moiety.
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formation of the Giardia Cyst wall studies on extracellular assembly using immunogold labeling and high resolution field emission sem
Journal of Eukaryotic Microbiology, 1996Co-Authors: Stanley L. Erlandsen, Paul T Macechko, Harry Van Keulen, Edward L. JarrollAbstract:EnCystment of the intestinal protozoan, Giardia, is a key step in the life cycle that enables this parasite to be transmitted from host to host via either fecal oral, waterborne, or foodborne transmission. The process of enCystment was studied by localizing Cyst wall specific antigens with immunofluorescence for light microscopy and immunogold staining for field emission scanning electron microscopy. Chronological sampling of Giardia cultures stimulated with endogenous bile permitted identification of an intracellular and extracellular phase in Cyst wall formation, a process which required a total of 14-16 h. The intracellular phase lasted for 8-10 h, while the extracellular phase, involved the appearance of Cyst wall antigen on the trophozoite membrane, and the assembly of the filamentous layer, a process requiring an additional 4-6 h for completion of mature Cysts. The extracellular phase was initiated with the appearance of Cyst wall antigen on small protrusions of the trophozoite membrane (∼15 nm), which became enlarged with time to caplike structures ranging up to 100 nm in diameter. Caplike structures involved with filament growth were detected over the entire surface of the trophozoite including the adhesive disc and flagella. EnCysting cells rounded up, lost attachment to the substratum, and became enclosed in a layer of filaments. Late stages in enCystment included a tailed Cyst in which flagella were not fully retracted into the Cyst. Clusters of Cysts were seen in which filaments at the surface of one Cyst were connected with the surface of adjacent Cysts or the tailed processes of adjacent Cysts, suggesting that the growth of Cyst wall filaments may be at the terminal end. In conclusion, the process of enCystment has been shown to consist of two morphologically different stages (intracellular and extracellular) which requires 16 h for completion. Further investigation of the extracellular stage with regard to assembly of the filamentous layer of the Cyst wall may lead to innovative methods for interfering with production of an intact functional Cyst wall, and thereby, regulation of viable Giardia Cyst release from the host.