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Prisons are high-risk settings for infectious disease transmission, due to their enclosed and semi-enclosed environments. The proximity between prisoners and staff, and the diversity of prisons reduces the effectiveness of non-pharmaceutical interventions, such as social distancing. Therefore, alternative health monitoring methods, such as wastewater-based epidemiology (WBE), are needed to track pathogens, including SARS-CoV-2. This pilot study assessed WBE to quantify SARS-CoV-2 prevalence in prison wastewater to determine its utility within a health protection system for residents. The study analysed 266 samples from six prisons in England over a 12-week period for nucleoprotein 1 (N1 gene) and envelope protein (E gene) using quantitative reverse transcriptase-polymerase chain reaction. Both gene assays successfully detected SARS-CoV-2 fragments in wastewater samples, with both genes significantly correlating with COVID-19 case numbers across the prisons (p < 0.01). However, in 25% of the SARS-positive samples, only one gene target was detected, suggesting that both genes be used to reduce false-negative results. No significant differences were observed between 14- and 2-h composite samples, although 2-h samples showed greater signal variance. Population normalisation did not improve correlations between the N1 and E genes and COVID-19 case data. Overall, WBE shows considerable promise for health protection in prison settings. HIGHLIGHTS Wastewater epidemiology is effective in flagging COVID-19 cases in prison settings.; SARS-CoV-2 levels were quantified using N1 and E gene targets.; Both targets should be used in routine analysis to reduce false negatives.; COVID-19 case numbers significantly correlated with both wastewater gene targets across all samples.; Each prison is different – local activities are important when designing sampling programmes.;

Abstract Recently, Vibrio tapetis was isolated for the first time from skin ulcerations in wild-caught common dab (Limanda limanda). To further examine its role in the development of these skin lesions, an in vivo experiment was performed. The significance of the skin barrier and in addition the difference between pigmented and non-pigmented side were investigated. Hence, the skin of common dab was treated in three different ways on both the pigmented and non-pigmented side. On a first “treatment zone”, the scales and overlying epidermal tissue were removed whereas in a second zone only the mucus was discarded. The third zone served as a non-treated zone. Thereafter, fish were challenged with V. tapetis. The control group was sham treated. Mortality, clinical signs, severity and size of the developing lesions were recorded. All animals were sacrificed and sampled 21 days post-inoculation. Significantly more fish of the group challenged with V. tapetis died compared to the control group with the highest incidence occurring 4 days post-inoculation. Fish challenged with V. tapetis developed more severe skin ulcerations. In zones where scales and epidermal tissue were removed, the ulcerations were more severe compared to zones where only mucus was eliminated. Ulcerations occurred more frequently, were more severe and larger on the pigmented side. Our data represents prove of V. tapetis as causative agent of ulcerative skin lesions although prior damage of the skin seems to be a major contributing factor. Furthermore, the pigmented side seemed predisposed to the development of skin ulcerations.

Urinary tract infections (UTIs) caused by resistant Klebsiella pneumoniae can lead to severe clinical complications and even death. An alternative treatment option for infected patients is using bacteriophages. In the present study, we isolated phage VB_KPM_KP1LMA (KP1LMA) from sewage water using a K. pneumoniae strain as a host. Whole-genome analysis indicated that the genome was a double-stranded linear 176,096-bp long DNA molecule with 41.8% GC content and did not contain virulence or antibiotic resistance genes. The inactivation potential of phage KP1LMA was assessed in broth at an MOI of 1 and 10, and a maximum inactivation of 4.9 and 5.4 log CFU/mL, respectively, was observed after 9 h. The efficacy at an MOI of 10 was also assessed in urine to evaluate the phage’s performance in an acidic environment. A maximum inactivation of 3.8 log CFU/mL was observed after 9 h. The results suggest that phage KP1LMA could potentially control a UTI caused by this strain of K. pneumoniae, indicating that the same procedure can be used to control UTIs caused by other strains if new specific phages are isolated. Although phage KP1LMA has a narrow host range, in the future, efforts can be made to expand its spectrum of activity and also to combine this phage with others, potentially enabling its use against other K. pneumoniae strains involved in UTIs.

Background: A One Health approach requires integrative research to elucidate antimicrobial resistance (AMR) in the environment and the risks it poses to human health. Research on this topic involves experts from diverse backgrounds and professions. Shortcomings exist in terms of consistent, complete, and transparent reporting in many environmental studies. Standardized reporting will improve the quality of scientific papers, enable meta-analyses and enhance the communication among different experts. In this study, we aimed to generate a consensus of reporting standards for AMR research in wastewater and related aquatic environments. Methods: Based on a risk of bias assessment of the literature in a systematic review, we proposed a set of study quality indicators. We then used a multistep modified Delphi consensus to develop the EMBRACE-WATERS statement (rEporting antiMicroBial ResistAnCE in WATERS), a checklist of recommendations for reporting in studies of AMR in wastewater and related aquatic environments. Findings: Consensus was achieved among a multidisciplinary panel of twenty-one experts in three steps. The developed EMBRACE-WATERS statement incorporates 21 items. Each item contains essential elements of high-quality reporting and is followed by an explanation of their rationale and a reporting-example. The EMBRACE-WATERS statement is primarily intended to be used by investigators to ensure transparent and comprehensive reporting of their studies. It can also guide peer-reviewers and editors in evaluation of manuscripts on AMR in the aquatic environment. This statement is not intended to be used to guide investigators on the methodology of their research. Interpretation: We are hopeful that this statement will improve the reporting quality of future studies of AMR in wastewater and related aquatic environments. Its uptake would generate a common language to be used among researchers from different disciplines, thus advancing the One Health approach towards understanding AMR spread across aquatic environments. Similar initiatives are needed in other areas of One Health research.

In this work, we studied a disease outbreak that affected meagre (Argyrosomus regius) at a temperature of 14–15 °C, and that reached a mortality rate of 45% in one week. Moribund fish showed neither external nor internal signs of disease. However, a large number of bacteria, phenotypically similar and in pure culture, were recovered from the liver and kidney. A further phenotypic, genotypic and serological characterization of a selection of three isolates (a828, a834 and a842) allowed the identification of them as Vibrio tapetis. Phylogenetic analysis placed the isolates within the subspecies tapetis, being clearly differentiated from the subspecies britannicus and quintayensis. Nevertheless, all the isolates showed some phenotypic discrepancies with the type strain CECT 4600T; also, they proved to belong to a different O-serotype and genogroup (according to REP-PCR analysis) than the type strain. A virulence evaluation performed in sea bass (Dicentrarchus labrax) by intraperitoneal injection using isolate a828 in two different doses (1 × 105 and 3 × 108 cfu/fish) led to mean mortality rates of 30% and 60%, respectively, corroborating its potential to cause significant mortalities in fish. To our knowledge, this is the first evidence of pathogenic Vibrio tapetis isolates associated with disease outbreaks in meagre.

To date, the genus Psychrobacter consists of 37 recognized species isolated from different sources, however they are more frequently found in cold and other non-polar environments of low water activity. Some strains belonging to the genus have shown different enzymatic activities with potential applications in bioremediation or food industry. In the present study, the whole genome sequences of three Psychrobacter-like strains (C 20.9, Cmf 22.2 and Rd 27.2) isolated from reared clams in Galicia (Spain) are described. The sequenced genomes resulted in an assembly size of 3,143,782 bp for C 20.9 isolate, 3,168,467 bp for Cmf 22.2 isolate and 3,028,386 bp for Rd 27.2 isolate. Among the identified coding sequences of the genomes, mercury detoxification and biogeochemistry genes were found, as well as genes related to heavy metals and antibiotic resistance. Also virulence-related features were identified such as the siderophore vibrioferrin or an aerobactin-like siderophore. The phylogenetic analysis of the 16S rRNA gene suggested that these strains may represent novel species of the Psychrobacter genus. The genome sequences of the Psychrobacter sp. strains have been deposited at DDBJ/EMBL/GenBank under the accession numbers MRYA00000000 (Cmf 22.2), MRYB00000000 (Rd 27.2) and MRYC00000000 (C 20.9), and the sequences could be found at the site https://www.ncbi.nlm.nih.gov/bioproject/PRJNA353858.

Emerging risk identification is a priority for the European Food Safety Authority (EFSA). The goal of the Galician Emerging Food Safety Risks Network (RISEGAL) is the identification of emerging risks in foods produced and commercialized in Galicia (northwest Spain) in order to propose prevention plans and mitigation strategies. In this work, RISEGAL applied a systematic approach for the identification of emerging food safety risks potentially affecting bivalve shellfish. First, a comprehensive review of scientific databases was carried out to identify hazards most quoted as emerging in bivalves in the period 2016–2018. Then, identified hazards were semiquantitatively assessed by a panel of food safety experts, who scored them accordingly with the five evaluation criteria proposed by EFSA: novelty, soundness, imminence, scale, and severity. Scores determined that perfluorinated compounds, antimicrobial resistance, Vibrio parahaemolyticus, hepatitis E virus (HEV), and antimicrobial residues are the emerging hazards that are considered most imminent and severe and that could cause safety problems of the highest scale in the bivalve value chain by the majority of the experts consulted (75%). Finally, in a preliminary way, an exploratory study carried out in the Galician Rías highlighted the presence of HEV in mussels cultivated in class B production areas.

Online social networks are increasingly used by the population on a daily basis. They are considered a powerful tool for science communication and their potential as educational tools is emerging. However, their usefulness in academic practice is still a matter of debate. Here, we present the results of our pioneering experience teaching a full Basic Microbiology course via Twitter (#microMOOCSEM), consisting of 28 lessons of 40-45 minutes duration each, at a tweet per minute rate during 10 weeks. Lessons were prepared by 30 different lecturers, covering most basic areas in Microbiology and some monographic topics of general interest (malaria, HIV, tuberculosis, etc.). Data analysis on the impact and acceptance of the course were largely affirmative, promoting a 330% enhancement in the followers and a >350-fold increase of the number of visits per month to the Twitter account of the host institution, the Spanish Society for Microbiology. Almost one third of the course followers were located overseas. Our study indicates that Massive Online Open Courses (MOOC) via Twitter are highly dynamic, interactive, and accessible to great audiences, providing a valuable tool for social learning and communicating science. This strategy attracts the interest of students towards particular topics in the field, efficiently complementing customary academic activities, especially in multidisciplinary areas like Microbiology.

Since the description of the genus Arcobacter in 1991, a total of 27 species have been described, although some species have shown 16S rRNA similarities below 95%, which is the cut-off that usually separates species that belong to different genera. The objective of the present study was to reassess the taxonomy of the genus Arcobacter using information derived from the core genome (286 genes), a Multilocus Sequence Analysis (MLSA) with 13 housekeeping genes, as well as different genomic indexes like Average Nucleotide Identity (ANI), in silico DNA–DNA hybridization (isDDH), Average Amino-acid Identity (AAI), Percentage of Conserved Proteins (POCPs), and Relative Synonymous Codon Usage (RSCU). The study included a total of 39 strains that represent all the 27 species included in the genus Arcobacter together with 13 strains that are potentially new species, and the analysis of 57 genomes. The different phylogenetic analyses showed that the Arcobacter species grouped into four clusters. In addition, A. lekithochrous and the candidatus species ‘A. aquaticus’ appeared, as did A. nitrofigilis, the type species of the genus, in separate branches. Furthermore, the genomic indices ANI and isDDH not only confirmed that all the species were well-defined, but also the coherence of the clusters. The AAI and POCP values showed intra-cluster ranges above the respective cut-off values of 60% and 50% described for species belonging to the same genus. Phenotypic analysis showed that certain test combinations could allow the differentiation of the four clusters and the three orphan species established by the phylogenetic and genomic analyses. The origin of the strains showed that each of the clusters embraced species recovered from a common or related environment. The results obtained enable the division of the current genus Arcobacter in at least seven different genera, for which the names Arcobacter, Aliiarcobacter gen. nov., Pseudoarcobacter gen. nov., Haloarcobacter gen. nov., Malacobacter gen. nov., Poseidonibacter gen. nov., and Candidate ‘Arcomarinus’ gen. nov. are proposed.

Hatcheries constitute nowadays the only viable solution to support the husbandry of bivalve molluscs due to the depletion and/or overexploitation of their natural beds. Hatchery activities include the broodstock conditioning and spawning, rearing larvae and spat, and the production of microalgae to feed all stages of the production cycle. However, outbreaks of disease continue to be the main bottleneck for successful larval and spat production, most of them caused by different representatives of the genus Vibrio. Therefore, attention must be paid on preventive and management measures that allow the control of such undesirable bacterial populations. The present review provides an updated picture of the recently characterized Vibrio species associated with disease of bivalve molluscs during early stages of development, including the controversial taxonomic affiliation of some of them and relevant advances in the knowledge of their virulence determinants. The problematic use of antibiotics, as well as its eco-friendly alternatives are also critically discussed.

The hepatitis E virus (HEV) affects almost 20 million individuals annually, causing approximately 3.3 million acute liver injuries, 56,600 deaths, and huge healthcare-associated economic losses. Shellfish produced close to urban and livestock areas can bioaccumulate this virus and transmit it to the human population. The aim of this study was to evaluate the presence of HEV in molluscan shellfish, in order to deepen the knowledge about HEV prevalence in Galicia (northwestern Spain), and to investigate this as a possible route of HEV transmission to humans. A total of 168 shellfish samples was obtained from two different Galician rías (Ría de Ares-Betanzos and Ría de Vigo). The samples were analyzed by reverse transcription-quantitative PCR (RT-qPCR). RT-nested PCR and sequencing were used for further genotyping and phylogenetic analysis of positive samples. HEV was detected in 41 (24.4%) samples, at quantification levels ranging from non-quantifiable (2 copies of the RNA genome (RNAc)/g tissue) to 1.1 × 105 RNAc/g tissue. Phylogenetic analysis based on the open reading frame (ORF)2 region showed that all sequenced isolates belonged to genotype 3, and were closely related to strains of sub-genotype e, which is of swine origin. The obtained results demonstrate a significant prevalence of HEV in bivalve molluscs from Galician rías, reinforcing the hypothesis that shellfish may be a potential route for HEV transmission to humans.

Viral agents of human gastroenteritis affect people of all ages across the globe. As a mainly self-limiting disease, it is difficult to evaluate the real prevalence of etiological agents circulating in each region. Many of the analyzed outbreaks are caused by viruses of the family Caliciviridae, especially the genus Norovirus (NoV). Most studies have focused on other enteric viruses, leaving sapovirus (SaV) underestimated as an important emerging human threat. This one-year study analyzed clinical samples from hospital outpatients with acute gastroenteritis in Spain, with the aim of revealing the importance of human SaV as an emerging viral pathogen. A total of 2667 stools were tested using reverse transcription (RT)-qPCR to detect and quantify SaV. Sapovirus was detected in all age groups, especially in infants, children, and the elderly. The prevalence was 15.64% (417/2667), and was slightly higher in 0⁻2- and 3⁻5-year-olds (19.53% and 17.95%, respectively) and much lower in 13⁻18-year-olds (9.86%). Positive samples were detected throughout the year, with peaks of detection during autumn and the late winter to early spring months. The mean value for the quantified samples was 6.5 × 105 genome copies per gram of stool (GC/g) (range 2.4 × 103⁻6.6 × 1011 GC/g). RT-nested PCR and sequencing were used for further genotyping. Genetic characterization showed a predominance of genogroup I (GI), followed by GII and GIV. The detection of multiple genotypes suggests the circulation of different strains without any clear tendency. The results obtained suggest SaV as the second major gastroenteritis agent after NoV in the region.

Phylogeographic patterns and population genetic structure of Yersinia ruckeri, the pathological agent of enteric redmouth disease (ERM) in salmonids, were investigated on the basis of concatenated multiloci sequences from isolates of different phenotypes obtained between 1965-2009 from diverse areas and hosts. Sequence analyses revealed genetic differentiation among subpopulations with the largest genetic distance occurring between subpopulations of Europe and Canada and/or South America. Bayesian analysis indicated the presence of three ancestral population clusters. Mismatch distribution displayed signatures characteristic of changes in size due to demographic and spatial expansions in the overall Y. ruckeri population, and also in the geographically separate subpopulations. Furthermore, a weak signal of isolation by distance was determined. A significant positive correlation between genetic and geographical distances was observed. These results revealed that the population of Y. ruckeri has undergone both ancient and recent population changes that were probably induced by biogeography forces in the past and, much more recently, by adaptive processes forced by aquaculture expansion. These findings have important implications for future studies on Y. ruckeri population dynamics, on the potential role of genetic structure to explain variations in ERM transmission, and on the effect of past evolutionary events on current estimations of gene flow.

The family Oceanospirillaceae (Garrity et al., 2005) includes 18 genera, 11 of which were described in the last 10 years (Arahal et al., 2007). Members of this family are motile and exclusive from aquatic environments. As part of a study on the microbiota associated to Great scallop (Pecten maximus) and its rearing system performed in a hatchery in Bergen (Norway), seven strains: 3CM4T(= CECT 8267T; = CAIM 1884T) 3CH4, 2CH8, 2SH3, 1CH5, 1CH6 and 1SH4 (= CECT 8268; = CAIM 1885) were isolated from broodstock gonads. These strains are aerobic, oxidase and catalase positive and they do not grow in TCBS. Isolates form small (less than 1 mm) pale brown pigmentated colonies on marine agar. They are halophiles and their temperature range for growth is 4 to 20ºC. Cells are Gram-negative, non-motile long rods, measuring 0.2-0.4 μm in diameter and 5-20 μm in length. With oxidative metabolism, the isolates do not ferment carbohydrates. The results of analysis of DNA-DNA hybridization confirmed that these isolates constitute a new and differentiated cluster within the genus Sinobacterium. The predominant fatty acids were C16: 0, C16: 1 ω7c/C16: 1 ω6c and C18: 1 ω7c. The G + C content of the new isolates is 52.2 ± 1 mol%. Based on phenotypic and phylogenetic characteristics, the seven isolates represent a new species for which the name Sinobacterium norvegicum sp. nov. is proposed, with strain 3CM4T (= CECT 8267T = CAIM 1884T) as the type strain.

Sapovirus (SaV), etiologic agent of human gastroenteritis, is a RNA virus from the Caliciviridae family, mostly detected in Asia. It has been classified by the U.S. Environmental Protection Agency as an emergent human pathogen with risk for public health in aquatic environments. Bivalves, due to their filtrating feeding, concentrate viral particles presented in seawater, and it has been demonstrated that the bioaccumulated viruses can resist depuration treatments to which bivalves are submitted. In addition, the traditional way of bivalve consumption increases the probability of infection, making them a high risk food [1]. The main objective of this work was to detect and quantify SaV in bivalves from Galicia, Northwestern Spain. A total of 168 samples, including mussels (Mytilus galloprovincialis), clams (Venerupis philippinarum and V. decussata) and cockles (Cerastoderma edule) were obtained during a period of 18 months from two Galician Rías (Ría of Ares-Betanzos and Ría of Vigo, respectively at North and South of the region). Samples consisted into 10 or 20 individuals, which were dissected under aseptic conditions to obtain their digestive tissue. The viral RNA was extracted using Nucleospin RNA Virus Kit (Macherey-Nagel; Dürem, Germany). Subsequently, viral detection and quantification by real time RT-PCR was performed using Platinum Quantitative RT-PCR Thermoscript One-Step System Kit (Invitrogen, Saint Aubin, France), according to the recently developed standard method ISO/TS 15216:2013. Primers SaV124F and SaV124R, and probe SaV124TP designed to amplify human genogroups I, II and IV were used [2]. Both through viral RNA extraction and viral detection and quantification, internal controls were used to avoid false positive or negative results, and the possible presence of inhibitors. SaV was detected in 30 of the 168 samples (17,85%). There was no significant difference between the two Rías in terms of detections, although it was observed a seasonality increment of positive samples from November 2011 until April 2012 in both Rías due to the rainy season and the decrease of seawater temperature. Total quantification ranged between 103 and 105 copies of viral RNA/g of digestive tissue (c/g), being mussels the specie with lower main quantification (3,1 x 104 c/g) and clams the species with higher medium rates (2,0 x 105 c/g). This represents the first study out of Japan in which human Sapovirus was detected and quantified into human food intended for consumption.

Enteric viruses contaminating the environment represent a danger for public health. They are present quite frequently in wastewater and transmitted to humans by the fecal-oral route. The aim of our study was to detect hepatitis A and E viruses (HAV and HEV) in wastewater samples collected from 6 different Tunisian sewage treatment plants during thirteen months. A total of 325 samples were analyzed by real time reverse transcriptase-polymerase chain reaction (RT-qPCR). Results showed the presence of HAV contamination in 36% of the samples. Msaken (58.9%) and SidiBouzid (51.85%) regions showed the highest contamination, followed by Ouerdanine (35.2%), Kasserine (38.9%), Sbitla (23.6%) and El Jem (7.7%) regions. Contamination with HEV was significantly lower (4.9%), being detected HEV positive samples in SidiBouzid (9.25%), El Jem (5.76%), Kasserine (3.7%), Ouerdanine (3.7%), Sbitla (3.63%) and Msaken (3.6%) regions. On the another hand, our research found that, in entry points, 54% of wastewater samples were contaminated with HAV, whereas, in exit points a percentage of 17.9% was found. HAV values were also analyzed by plant showing percentages of positive samples in entry points between 15.38% and 85.18%, while in exit points values ranged from 3.57% to 57.14%. HAV was detected in exit points of all plants except El Jem region. Concerning HEV, the average percentage of contaminated wastewater at entry was 6.75% which was reduced until 3.1% at exit. By plant, HEV positive samples were detected only in three plants, Kasserine, El Jem and Sidi Bouzid at rates of 3.7% 3.84% and 11.11%, respectively. These results support previous findings on the stability of enteric viruses in wastewater and the inefficiency of the procedures employed in the sewage treatment plants. On the other hand, molecular procedures proved to be very sensitive to detect viral genomes in this type of samples. In conclusion, wastewater treatments employed in Tunisian plants can reduce the number of viral particles of hepatitis A and E but do not remove all of them, which constitute a potential risk for human health.

Bivalve molluscs, due to its filter-feeding mechanism, have an abundant associated bacterial microbiota composed of a large number of species of different genera. The knowledge about the composition of the microbiota associated with bivalve molluscs is based, mostly, on techniques of cultivation of microorganisms, but also on DGGE methods. However, it is estimated that less than 1% of the bacteria are culturable with current methods, which lead to an underestimation of the microbial diversity. On the other hand, DGGE methodology has a limited resolution due to the low number of DNA fragments obtained as representative of a microbial community. The introduction of new molecular approaches allowed the improvement of the knowledge about bacterial communities present in a sample [1]. In recent years, new molecular techniques known as Next Generation Sequencing (NGS) have been developed, based on high- throughput sequencing [2]. In this study, we present the analysis of the microbiota associated to reared scallop gonads before and after spawning by pyrosequencing of the 16S rRNA gene. After the DNA extraction of the samples, amplification was performed using a set of degenerate primers with low stringency conditions. Pyrosequencing of samples was carried out using the sequencer 454 GLX Titanium Plus (Roche). The data obtained was further subjected to bioinformatics analysis using Galaxy and UCHIME program and the Ribosomal Database Project. Rarefaction curves were obtained, the composition of the bacterial community was analysed after the taxonomic assignment, and the total composition of the bacterial communities of the samples were compared using the principal coordinates analysis (PCoA) by FastUnifrac tool [3]. Pyrosequencing of the samples resulted in a total of 18520 sequences (3000 per sample, approximately) with an average length of 325 bp (base pairs). The taxonomic assignment of sequences allowed the identification to the genus level, being observed a large bacterial diversity with over 110 genera. The most prevalent genera in the samples were Hydrotalea, Acinetobacter, Delftia, Sediminibacter and Pseudomonas, among others. Differences in the microbial communities were observed among the samples, and the PCoA analysis allowed their separation by means on their gender and if they proceed from sampling before or after the spawning. Nevertheless, the rarefaction curves obtained for each sample failed to reach a saturation phase, indicating that more sequencing effort would be necessary.

From a virological standpoint, shellfish safety continues to be a sanitary challenge. Bivalves are one of the most common vehicles of viral illness and the adoption of viral standards into European Union legislation is being considered. In this study, a 18-months survey were conducted in ten harvesting areas from two estuaries in Galicia (NW of Spain), the most important bivalve production area in Europe. Hepatitis A virus (HAV) and human norovirus (NoV), including genogroups I (GI) and II (GII) were quantified by reverse transcription-real time PCR (RT-qPCR), according to the recently developed standard method ISO/TS 15216:2013. Four bivalve species were studied, including wild and cultured mussels (Mytilus galloprovincialis), clams (Venerupis philippinarum and V. decussata) and cockles (Cerastoderma edule). Overall, 54.8% of the analysed samples were contaminated by at least one of the studied viruses, being detected the simultaneous presence of two or three viruses in 11.3% of the samples. NoV GI was the most prevalent virus (32.1%) followed by NoV GII (25.6%) and HAV (9.5%). The results showed the presence of viral contamination throughout the year in both areas and all species of molluscs. However, diverse patterns of prevalence and seasonality were observed among different viruses. HAV was detected only between March and June 2012. NoV GI was detected intermittently throughout the study period, with significant peaks in the spring and summer of 2011. NoV GII showed a clear seasonality to during the cold months by 2011; however, a significant peak was detected in the spring of 2012.

The genus Vibrio consists of more than 100 species grouped in 14 clades that are widely distributed in aquatic environments such as estuarine, coastal waters and sediments. A large number of species of this genus are associated with marine organisms like fish, molluscs and crustaceans, in commensal or pathogenic relations. In the last decade, more than 50 new species have been described in the genus Vibrio, due to the introduction of new molecular techniques in bacterial taxonomy, such as multilocus sequence analysis (MLSA) or fluorescent amplified fragment length polymorphism (FAFLP). On the other hand, the increasing number of environmental studies has contributed to improve the knowledge about the family Vibrionaceae and its phylogeny. Vibrio crassostreae, V. breoganii, V. celticus are some of the new Vibrio species described as forming part of the molluscan microbiota. Some of them have been associated with mortalities of different molluscan species, seriously affecting their culture and causing high losses in hatcheries as well as in natural beds. For other species, ecological importance has been demonstrated being highly abundant in different marine habitats and geographical regions. The present work provides an updated overview of the recently characterized Vibrio species isolated from molluscs. In addition, their pathogenic potential and/or environmental importance is discussed.