Evaluation of a suspended radiation protection system to reduce operator exposure in cardiology interventional procedures.

OBJECTIVES: To investigate a novel suspended radiation shield (ZG), in reducing operator radiation exposure during cardiology interventions. BACKGROUND: Radiation exposure to the operator remains an occupational health hazard in the cardiac catheterization laboratory. METHODS: An anthropomorphic mannequin simulating an operator was placed near a phantom, simulating a patient. To measure the operator dose reduction, thermoluminescent detectors (TLDs) were inserted into the head and into the eye bulbs of the mannequin, while electronic dosimeters were positioned on the temple and at the level of the thyroid. Measurements were performed without and with the ZG system in place. Physician exposure was subsequently prospectively measured on the torso, on the left eye and on upper arm using the same electronic dosimeters, during clinical procedures (coronary angiography (CA) and percutaneous coronary intervention (PCI)). The physicians dose reduction was assessed by comparing operator dose when using traditional radioprotection garments (Phase 0) versus using the ZG system (Phase 1). RESULTS: Dose reductions as measured on the mannequin ranged from 66% to the head, to 100% to the torso. No dose was detected at the level of the torso and thyroid with ZG. When comparing CA and PCI procedures between Phase 0 and Phase 1, a significant difference (p < 0.001) was found for the left eye and the left wrist. Dose reduction as measured during clinical procedures for left eye/upper arm were on average 78.9%/95.6% for CA and 83.0%/93.0% for PCI, respectively (p < 0.001 for both). CONCLUSIONS: The ZG systems has a great potential to significantly reduce operator dose through the creation of a nearly zero-radiation work environment.

Campylobacter armoricus sp. nov., a novel member of the Campylobacter lari group isolated from surface water and stools from humans with enteric infection.

During a study on the prevalence and diversity of members of the genus Campylobacter in a shellfish-harvesting area and its catchment in Brittany, France, six urease-positive isolates of members of the genus Campylobacter were recovered from surface water samples, as well as three isolates from stools of humans displaying enteric infection in the same period. These strains were initially identified as members of the Campylobacter lari group by MALDI-TOF mass spectrometry and placed into a distinct group in the genus Campylobacter, following atpA gene sequence analysis based on whole-genome sequencing data. This taxonomic position was confirmed by phylogenetic analysis of the 16S rRNA, rpoB and hsp60 (groEL) loci, and an analysis of the core genome that provided an improved phylogenetic resolution. The average nucleotide identity between the representative strain CA656T (CCUG 73571T=CIP 111675T) and the type strain of the most closely related species Campylobacter ornithocola WBE38T was 88.5 %. The strains were found to be microaerobic and anaerobic, motile, non-spore-forming, Gram-stain-negative, spiral-shaped bacteria that exhibit catalase, oxidase and urease activities but not nitrate reduction. This study demonstrates clearly that the nine isolates represent a novel species within the C. lari group, for which the name Campylobacter armoricus is proposed. Here, we present phenotypic and morphological features of the nine strains and the description of their genome sequences. The proposed type strain CA656T has a 1.589 Mbp chromosome with a DNA G+C content of 28.5 mol% and encodes 1588 predicted coding sequences, 38 tRNAs, and 3 rRNA operons.

Novel Insights from Comparative In Silico Analysis of Green Microalgal Cellulases.

The assumption that cellulose degradation and assimilation can only be carried out by heterotrophic organisms was shattered in 2012 when it was discovered that the unicellular green alga, Chlamydomonas reinhardtii (Cr), can utilize cellulose for growth under CO2-limiting conditions. Publications of genomes/transcriptomes of the colonial microalgae, Gonium pectorale (Gp) and Volvox carteri (Vc), between 2010⁻2016 prompted us to look for cellulase genes in these algae and to compare them to cellulases from bacteria, fungi, lower/higher plants, and invertebrate metazoans. Interestingly, algal catalytic domains (CDs), belonging to the family GH9, clustered separately and showed the highest (33⁻42%) and lowest (17⁻36%) sequence identity with respect to cellulases from invertebrate metazoans and bacteria, respectively, whereas the identity with cellulases from plants was only 27⁻33%. Based on comparative multiple alignments and homology models, the domain arrangement and active-site architecture of algal cellulases are described in detail. It was found that all algal cellulases are modular, consisting of putative novel cysteine-rich carbohydrate-binding modules (CBMs) and proline/serine-(PS) rich linkers. Two genes were found to encode a protein with a putative Ig-like domain and a cellulase with an unknown domain, respectively. A feature observed in one cellulase homolog from Gp and shared by a spinach cellulase is the existence of two CDs separated by linkers and with a C-terminal CBM. Dockerin and Fn-3-like domains, typically found in bacterial cellulases, are absent in algal enzymes. The targeted gene expression analysis shows that two Gp cellulases consisting, respectively, of a single and two CDs were upregulated upon filter paper addition to the medium.

Multilayer Flow Modulator Treatment of Abdominal and Thoracoabdominal Aortic Aneurysms With Side Branch Coverage: Outcomes From a Prospective Single-Center Moroccan Registry.

PURPOSE: To evaluate endovascular repair of thoracoabdominal aortic aneurysms (TAAA) and abdominal aortic aneurysms (AAA) using the Multilayer Flow Modulator (MFM) in high-surgical-risk patients with at least one covered branch vessel. METHODS: In this prospective single-center nonrandomized trial, 18 patients (mean age 61.1 years; 16 men) with TAAA (n=10, mean diameter 74.4 mm) and AAA (n=8, mean diameter 67.8 mm) were treated with the MFM between June 2009 and September 2012. The primary safety endpoints were all-cause mortality at 30 days and 12 months and neurological complications. The primary efficacy endpoint was overall procedure success, defined as patency of covered branch vessels, reductions in aneurysm diameter, and sac thrombus formation. RESULTS: The technical success rate was 100% (53 study devices implanted, mean stented length 273 mm). Through mean follow-up of 13.4 months, all 61 covered branch vessels remained patent; there were no neurologic complications, ruptures, or instances of device migration, kinking, or fracture. Three patients died, 2 of unrelated causes and one of an undetermined cause. Only one reintervention with an additional MFM implanted at 5 years was required for a type I endoleak in a young patient with natural growth. Carefully planned and executed diameter and volume measurements demonstrated aneurysm shrinkage and progressive sac thrombus formation for both patient groups. CONCLUSION: Through midterm follow-up, treatment of high-surgical-risk TAAA and AAA patients with the MFM appears to be safe and effective, maintaining branch vessel patency and reducing rupture risk through reduction of aneurysm diameter and modulation of flow dynamics. Longer term follow-up is needed.

Investigating the host specificity of Campylobacter jejuni and Campylobacter coli by sequencing gyrase subunit A.

BACKGROUND: Surveillance and field investigations of Campylobacter infections require molecular tools with genetic markers appropriate for tracing purposes, i.e. based on the principle that some Campylobacter lineages acquire a host signature under adaptive selection pressure. We developed a sequence-based method targeting the quinolone resistance determining region within the subunit A of DNA gyrase (gyrA). Host specificity was evaluated by characterizing two collections of Campylobacter jejuni (N = 430) and Campylobacter coli (N = 302) originating from surface waters, domestic mammals and poultry. RESULTS: Based on nucleotide identity, a total of 80 gyrA alleles were observed. Thirty nine alleles assigned to C. coli encoding two peptides fell into three clades: two associated with surface waters and one associated with domestic mammals and poultry. The variability in GC content generated by synonymous mutations suggested that surface waters isolates originated from two distinct ecological niches. A total of 42 alleles were recorded from C. jejuni strains and encoded 8 peptides including one lying in a distinct lineage associated with wildlife. Seven of the 23 alleles encoding peptide #1 displayed the synonymous mutation G408A not identified in poultry isolates. By contrast, the substitution Ser22Gly observed in 4 different peptide groups was significantly associated with domestic birds (P = 0.001). The change in amino acid sequences Thr86Ile conferring resistance to quinolones was significantly associated with poultry (P < 0.001) in both C. jejuni and C. coli with 38.7% and 67.9% of quinolone-resistant strains, respectively. CONCLUSIONS: The gyrA typing method presented here is an informative tool as sequences appear to be predictive of particular ecological niches. Combined with multi-locus sequence typing, it could increase the resolution of source attribution, and combined with porA/flaA typing it could be suitable for detecting temporal clusters of human cases. All gyrA alleles identified were deposited in the freely accessible online database http://pubmlst.org/campylobacter.

Somatic hypermutation of human mitochondrial and nuclear DNA by APOBEC3 cytidine deaminases, a pathway for DNA catabolism.

The human APOBEC3 (A3A-A3H) locus encodes six cytidine deaminases that edit single-stranded DNA, the result being DNA peppered with uridine. Although several cytidine deaminases are clearly restriction factors for retroviruses and hepadnaviruses, it is not known if APOBEC3 enzymes have roles outside of these settings. It is shown here that both human mitochondrial and nuclear DNA are vulnerable to somatic hypermutation by A3 deaminases, with APOBEC3A standing out among them. The degree of editing is much greater in patients lacking the uracil DNA-glycolyase gene, indicating that the observed levels of editing reflect a dynamic composed of A3 editing and DNA catabolism involving uracil DNA-glycolyase. Nonetheless, hyper- and lightly mutated sequences went hand in hand, raising the hypothesis that recurrent low-level mutation by APOBEC3A could catalyze the transition from a healthy to a cancer genome.

Two-day detection of infectious enteric and non-enteric adenoviruses by improved ICC-qPCR.

In order to provide a more suitable response to public health concerns, we improved the detection of infectious human adenoviruses in water by optimising the commonly used integrated cell culture-PCR method. Risk evaluation studies seek for rapid detection of infectious adenoviruses, including the enteric types 40 and 41 that are considered as the second most common agents of gastroenteritis in children next to rotaviruses. The here-employed 293A cell line used for infectious status assessment showed its ability to multiply adenoviruses including type 41. Two modifications were moreover applied to the workflow for viral detection. The first occurred at the nucleic acid extraction step performed directly on all infected cells, while the second was the application of real-time quantitative PCR as detection tool. All adaptations led to a 3-day reduction of the response delay and an improved sensitivity especially for the enteric adenoviral types. The infectious status of laboratory strain types 2 and 41 was demonstrated by a more than 2-log10 increase in genome quantity. These conclusions were confirmed and reinforced by the analysis of water samples applying the improved assay. Naturally occurring infectious adenoviruses were detected in wastewater and river water, within 2 days. Types belonging to the species human adenoviruses C and type 31 were observed, but the most frequently identified type was 41 (71 % of identified sequences, n = 34). This highlights the usefulness of our method for a wide range of types, and especially for the most prevalent and public health-relevant enteric adenoviruses.

Persistence of endogenous RNA biomarkers of SARS-CoV-2 and PMMoV in raw wastewater: Impact of temperature and implications for wastewater-based epidemiology.

Understanding the persistence of SARS-CoV-2 biomarkers in wastewater should guide wastewater-based epidemiology users in selecting best RNA biomarkers for reliable detection of the virus during current and future waves of the pandemic. In the present study, the persistence of endogenous SARS-CoV-2 were assessed during one month for six different RNA biomarkers and for the pepper mild mottle virus (PMMoV) at three different temperatures (4, 12 and 20 °C) in one wastewater sample. All SARS-CoV-2 RNA biomarkers were consistently detected during 6 days at 4° and differences in signal persistence among RNA biomarkers were mostly observed at 20 °C with N biomarkers being globally more persistent than RdRP, E and ORF1ab ones. SARS-CoV-2 signal persistence further decreased in a temperature dependent manner. At 12 and 20 °C, RNA biomarker losses of 1-log10 occurred on average after 6 and 4 days, and led to a complete signal loss after 13 and 6 days, respectively. Besides the effect of temperature, SARS-CoV-2 RNA signals were more persistent in the particulate phase compared to the aqueous one. Finally, PMMoV RNA signal was highly persistent in both phases and significantly differed from that of SARS-CoV-2 biomarkers. We further provide a detailed overview of the latest literature on SARS-CoV-2 and PMMoV decay rates in sewage matrices.

Metagenomic Strain-Typing Combined with Isolate Sequencing Provides Increased Resolution of the Genetic Diversity of Campylobacter jejuni Carriage in Wild Birds.

As the world's leading cause of human gastro-enteritis, the food- and waterborne pathogen Campylobacter needs to be intensively monitored through a One Health approach. Particularly, wild birds have been hypothesized to contribute to the spread of human clinical recurring C. jejuni genotypes across several countries. A major concern in studying epidemiological dynamics is resolving the large genomic diversity of strains circulating in the environment and various reservoirs, challenging to achieve with isolation techniques. Here, we applied a passive-filtration method to obtain isolates and in parallel recovered genotypes from metagenomic sequencing data from associated filter sweeps. For genotyping mixed strains, a reference-based computational workflow to predict allelic profiles of nine extended-MLST loci was utilized. We validated the pipeline by sequencing artificial mixtures of C. jejuni strains and observed the highest prediction accuracy when including obtained isolates as references. By analyzing metagenomic samples, we were able to detect over 20% additional genetic diversity and observed an over 50% increase in the potential to connect genotypes across wild-bird samples. With an optimized filtration method and a computational approach for genotyping strain mixtures, we provide the foundation for future studies assessing C. jejuni diversity in environmental and clinical settings at improved throughput and resolution.

Environmental dynamics of Campylobacter jejuni genotypes circulating in Luxembourg: what is the role of wild birds?

Campylobacter jejuni is the leading cause of bacterial gastroenteritis worldwide, but, unlike other foodborne pathogens, is not commonly reported as causing outbreaks. The population structure of the species is characterized by a high degree of genetic diversity, but the presence of stable clonally derived genotypes persisting in space and time, and potentially leading to diffuse outbreaks, has recently been identified. The spread of these recurring genotypes could be enhanced by wild birds, suspected to act as vectors for a wide range of microorganisms that can be transmissible to other animals or humans. This study assessed the genetic diversity of C. jejuni carriage in wild birds and surface waters to explore a potential link between these environments and the persistence over years of recurring lineages infecting humans in Luxembourg. These lineages corresponded to over 40 % of clinical isolates over a 4 year period from 2018 to 2021. While mainly exotic genotypes were recovered from environmental samples, 4 % of C. jejuni from wild birds corresponded to human recurring genotypes. Among them, a human clinical endemic lineage, occurring for over a decade in Luxembourg, was detected in one bird species, suggesting a possible contribution to the persistence of this clone and its multi-host feature. Whereas 27 % of wild birds were carriers of C. jejuni, confirming their role as spreader or reservoir, only three out of 59 genotypes overlapped with recurring human strains. While direct transmission of C. jejuni infection through wild birds remains questionable, they may play a key role in the environmental spreading of stable clones to livestock, and this issue merits further investigation.

Molecular and morphological diversity of fungi and the associated functions in three European nearby lakes.

This study presents an original rDNA PCR and microscopic survey of pelagic freshwater fungal communities, and was designed to unveil the diversity of true Fungi (i.e. the kingdom Eumycota) in three contrasting lake ecosystems (Lakes Pavin, Aydat and Vassivière) located in the French Massif Central. Three clone libraries were constructed from samples collected in the euphotic layers of the lakes during spring 2007. Phylogenetic analysis of the combined data from the three lakes clustered our sequences into thee divisions: Chytridiomycota (50% of total sequences), Ascomycota (40%) and Basidiomycota (10% in Pavin and Aydat only). Several sequences were assigned to a novel Chytridiomycota clade first recovered in Lake Pavin in 2005. Most of the sequences retrieved in the investigated lakes were affiliated with known fungal species, most of which were apparently well adapted to thrive in the pelagic realm. Their main functions (i.e. parasitism and saprophytism), putatively inferred from the closest relatives of the retrieved molecular sequences, were confirmed by microscopic approaches and by enrichment experiments with pollen grains. The occurrence of three fungal forms (zoosporic, yeast and mycelial) was associated with different trophic modes, establishing fungi as strong potential competitors for various niches in pelagic ecosystems, primarily in relation to the processing of particulate organic matter and the production of propagule food sources for grazers. For the first time, this study provides insight into the diversity and the associated functions of all members of the Kingdom Eumycota investigated in the whole plankton fraction of aquatic ecosystems.

Lethal mutagenesis of foot-and-mouth disease virus involves shifts in sequence space.

Lethal mutagenesis or virus transition into error catastrophe is an antiviral strategy that aims at extinguishing a virus by increasing the viral mutation rates during replication. The molecular basis of lethal mutagenesis is largely unknown. Previous studies showed that a critical substitution in the foot-and-mouth disease virus (FMDV) polymerase was sufficient to allow the virus to escape extinction through modulation of the transition types induced by the purine nucleoside analogue ribavirin. This substitution was not detected in mutant spectra of FMDV populations that had not replicated in the presence of ribavirin, using standard molecular cloning and nucleotide sequencing. Here we selectively amplify and analyze low-melting-temperature cDNA duplexes copied from FMDV genome populations passaged in the absence or presence of ribovirin Hypermutated genomes with high frequencies of A and U were present in both ribavirin -treated and untreated populations, but the major effect of ribavirin mutagenesis was to accelerate the occurrence of AU-rich mutant clouds during the early replication rounds of the virus. The standard FMDV quasispecies passaged in the absence of ribavirin included the salient transition-modulating, ribavirin resistance mutation, whose frequency increased in populations treated with ribavirin. Thus, even nonmutagenized FMDV quasispecies include a deep, mutationally biased portion of sequence space, in support of the view that the virus replicates close to the error threshold for maintenance of genetic information.

Double-stranded RNA adenosine deaminase ADAR-1-induced hypermutated genomes among inactivated seasonal influenza and live attenuated measles virus vaccines.

We sought to examine ADAR-1 editing of measles and influenza virus genomes derived from inactivated seasonal influenza and live attenuated measles virus vaccines grown on chicken cells as the culture substrate. Using highly sensitive 3DI-PCR (R. Suspène et al., Nucleic Acids Res. 36:e72, 2008), it was possible to show that ADAR-1 could hyperdeaminate adenosine residues in both measles virus and influenza virus A genomes. Detailed analysis of the dinucleotide editing context showed preferences for 5'ArA and 5'UrA, which is typical of editing in mammalian cells. The hyperedited mutant frequency, including genomes and antigenomes, was a log greater for influenza virus compared to measles virus, suggesting a greater sensitivity to restriction by ADAR-1.

Massive APOBEC3 editing of hepatitis B viral DNA in cirrhosis.

DNA viruses, retroviruses and hepadnaviruses, such as hepatitis B virus (HBV), are vulnerable to genetic editing of single stranded DNA by host cell APOBEC3 (A3) cytidine deaminases. At least three A3 genes are up regulated by interferon-alpha in human hepatocytes while ectopic expression of activation induced deaminase (AICDA), an A3 paralog, has been noted in a variety of chronic inflammatory syndromes including hepatitis C virus infection. Yet virtually all studies of HBV editing have confined themselves to analyses of virions from culture supernatants or serum where the frequency of edited genomes is generally low (< or = 10(-2)). We decided to look at the nature and frequency of HBV editing in cirrhotic samples taken during removal of a primary hepatocellular carcinoma. Forty-one cirrhotic tissue samples (10 alcoholic, 10 HBV(+), 11 HBV(+)HCV(+) and 10 HCV(+)) as well as 4 normal livers were studied. Compared to normal liver, 5/7 APOBEC3 genes were significantly up regulated in the order: HCV+/-HBV>HBV>alcoholic cirrhosis. A3C and A3D were up regulated for all groups while the interferon inducible A3G was over expressed in virus associated cirrhosis, as was AICDA in approximately 50% of these HBV/HCV samples. While AICDA can indeed edit HBV DNA ex vivo, A3G is the dominant deaminase in vivo with up to 35% of HBV genomes being edited. Despite these highly deleterious mutant spectra, a small fraction of genomes survive and contribute to loss of HBeAg antigenemia and possibly HBsAg immune escape. In conclusion, the cytokine storm associated with chronic inflammatory responses to HBV and HCV clearly up regulates a number of A3 genes with A3G clearly being a major restriction factor for HBV. Although the mutant spectrum resulting from A3 editing is highly deleterious, a very small part, notably the lightly edited genomes, might help the virus evolve and even escape immune responses.

Endovascular treatment of a tuberculous thoracoabdominal aneurysm with the Multilayer stent.

PURPOSE: To describe a case of multiple thoracoabdominal aneurysms of tuberculous origin treated in an endovascular procedure with the Multilayer stent. CASE REPORT: A 16-year-old girl had been treated 4 years previously for a ruptured abdominal aortic aneurysm of tuberculous origin. Due to the presence of 4 rapidly evolving saccular aneurysms of the descending thoracic aorta and a fusiform aneurysm of the suprarenal aorta, an endovascular solution was chosen after the patient refused open surgery. Three uncovered Multilayer stents (16×40, 16×80, and 16×80 mm) were successively implanted with a 1-cm overlap from the left subclavian artery to cover the entire aneurysmal segment of the thoracoabdominal aorta to above the renal arteries. At 18 months, serial imaging studies have shown disappearance of some aneurysms and regression of others. CONCLUSION: In this young patient, the endovascular treatment of a thoracoabdominal aneurysm with an uncovered stent made it possible to stabilize the aneurysm process without exposing the patient to the high morbidity and mortality of open surgery.

Bacteriophages pass through candle-shaped porous ceramic filters: Application for the collection of viruses in soil water.

Despite the ubiquity of viruses in soils, their diversity in soil water has not been explored, mainly due to the difficulty of collecting them. In hydrology, soil water is usually collected using porous candles. This study proposes using these porous candles as a new tool for sampling viruses in soil water to analyze their passage through the ceramic part of the candles. The recovery of the viruses was determined after filtration under laboratory conditions using three model bacteriophages (MS2, ΦX174, and Φ6) and Escherichia coli, at neutral and acidic pH. Then, a field experiment was carried out where soil water filtration and viral identification by metagenomic shotgun were performed. At neutral pH, all bacteriophages tested successfully passed through the porous candles during the filtration process, with reductions of 0.02 log, 0.16 log, and 0.55 log for MS2 ΦX174 and Φ6, respectively. At pH 4.4, the passage of MS2 was not affected while ΦX174 underwent a slight reduction in recovery, probably caused by adsorption onto the filter material. Regarding the application of the porous candles in the field, the results obtained allowed the successful recovery of viruses, exposing porous candles as a new method suitable for the collection of viruses from soil water in the context of the study of viral communities.

Soil pH, Calcium Content and Bacteria as Major Factors Responsible for the Distribution of the Known Fraction of the DNA Bacteriophage Populations in Soils of Luxembourg.

Bacteriophages participate in soil life by influencing bacterial community structure and function, biogeochemical cycling and horizontal gene transfer. Despite their great abundance, diversity, and importance in microbial processes, they remain little explored in environmental studies. The influence of abiotic factors on the persistence of bacteriophages is now recognized; however, it has been mainly studied under experimental conditions. This study aimed to determine whether the abiotic factors well-known to influence bacteriophage persistence also control the natural distribution of the known DNA bacteriophage populations. To this end, soil from eight study sites including forests and grasslands located in the Attert River basin (Grand Duchy of Luxembourg) were sampled, covering different soil and land cover characteristics. Shotgun metagenomics, reference-based bioinformatics and statistical analyses allowed characterising the diversity of known DNA bacteriophage and bacterial communities. After combining soil properties with the identified DNA bacteriophage populations, our in-situ study highlighted the influence of pH and calcium cations on the diversity of the known fraction of the soil DNA bacteriophages. More interestingly, significant relationships were established between bacteriophage and bacterial populations. This study provides new insights into the importance of abiotic and biotic factors in the distribution of DNA bacteriophages and the natural ecology of terrestrial bacteriophages.

Model-based assessment of COVID-19 epidemic dynamics by wastewater analysis.

Continuous surveillance of COVID-19 diffusion remains crucial to control its diffusion and to anticipate infection waves. Detecting viral RNA load in wastewater samples has been suggested as an effective approach for epidemic monitoring and the development of an effective warning system. However, its quantitative link to the epidemic status and the stages of outbreak is still elusive. Modelling is thus crucial to address these challenges. In this study, we present a novel mechanistic model-based approach to reconstruct the complete epidemic dynamics from SARS-CoV-2 viral load in wastewater. Our approach integrates noisy wastewater data and daily case numbers into a dynamical epidemiological model. As demonstrated for various regions and sampling protocols, it quantifies the case numbers, provides epidemic indicators and accurately infers future epidemic trends. Following its quantitative analysis, we also provide recommendations for wastewater data standards and for their use as warning indicators against new infection waves. In situations of reduced testing capacity, our modelling approach can enhance the surveillance of wastewater for early epidemic prediction and robust and cost-effective real-time monitoring of local COVID-19 dynamics.

Concentration and diversity of noroviruses detected in Luxembourg wastewaters in 2008-2009.

Noroviruses (NoV) in 78 wastewater samples from Luxembourg were quantified, cloned, and sequenced in 2008-2009. The concentrations of NoV genogroup II and the relative occurrences of certain genotypes changed significantly during the winter season. NoV genogroup I was frequently detected by real-time reverse transcription-PCR (RT-PCR), albeit at 30-fold lower concentrations than for genogroup II, hampering attempts to assess overall genetic diversity by the cloning/sequencing approach.

Two-year monitoring of Cryptosporidium parvum and Giardia lamblia occurrence in a recreational and drinking water reservoir using standard microscopic and molecular biology techniques.

Starting in 2006, a monitoring of Giardia lamblia and Cryptosporidium parvum occurrence was conducted for 2 years in the largest drinking water reservoir of Luxembourg (Esch-sur-Sûre reservoir) using microscopy and qPCR techniques. Parasite analyses were performed on water samples collected from three sites: site A located at the inlet of the reservoir, site B located 18 km downstream site A, at the inlet of the drinking water treatment plant near the dam of the reservoir and site C where the finished drinking water is injected in the distribution network. Results show that both parasites are present in the reservoir throughout the year with a higher occurrence of G. lamblia cysts compared to C. parvum oocysts. According to our results, only 25% of the samples positive by microscopy were confirmed by qPCR. (Oo)cyst concentrations were 10 to 100 times higher at site A compared to site B and they were positively correlated to the water turbidity and negatively correlated to the temperature. Highest (oo)cyst concentrations were observed in winter. In contrast, no relationship between the concentrations of (oo)cysts in the reservoir and rain events could be established. Though a correlation has been observed between both parasites and faecal indicators in the reservoir, some discrepancies highlight that the latter do not represent a reliable tool to predict the presence/absence of these pathogenic protozoa. In summer 2007, the maximal risk of parasite infection per exposure event for swimmers in the reservoir was estimated to be 0.0015% for C. parvum and 0.56% for G. lamblia. Finally, no (oo)cysts could be detected in large volumes of finished drinking water.