First detection of Ichthyophonus sp. in invasive wild pink salmon (Oncorhynchus gorbuscha) from the North Atlantic Ocean.

Pacific pink salmon (Oncorhynchus gorbuscha) were deliberately introduced to rivers surrounding the White Sea and has spread to Norway and several other countries surrounding the North Atlantic Ocean. In August 2021, a female pink salmon displaying pale gills and abnormal behaviour was captured in River Lakselva in Northern Norway and later submitted to the Norwegian Veterinary Institute (NVI) for post-mortem examination. Histological examination of organ samples revealed structures indicative of systemic ichthyophoniasis, caused by Ichthyophonus sp. The parasites appeared to be especially abundant in the heart and skeletal musculature, and local tissue responses were assessed to be absent or very mild. Sequences of the ribosomal 18S rRNA and the mitochondrial cytochrome oxidase 1 (CO1) genes confirmed the diagnosis and identified the pathogen as Ichthyophonus sp. The CO1 sequence further established that the isolate from pink salmon was most similar to sequences of Ichthyophonus sp. from Atlantic salmon, Salmo salar, from the Atlantic Ocean on the east coast of the US and from Atlantic herring, Clupea harengus, from Iceland. We here report the first detection of Ichthyophonus sp. in pink salmon in the North Atlantic Ocean.

Insights from Hi-C data regarding the Pacific salmon louse (Lepeophtheirus salmonis) sex chromosomes.

Salmon lice, Lepeophtheirus salmonis (family Caligidae), are ectoparasites that have negatively impacted the salmon aquaculture industry and vulnerable wild salmon populations. Researchers have studied salmon lice to better understand their biology to develop effective control strategies. In this study, we updated the chromosome-level reference genome assembly of the Pacific subspecies of L. salmonis using Hi-C data. The previous version placed contigs/scaffolds using an Atlantic salmon louse genetic map. By utilizing Hi-C data from Pacific salmon lice, we were able to properly assign locations to contigs/scaffolds previously unplaced or misplaced. This resulted in a more accurate genome assembly and a more comprehensive characterization of the sex chromosome unique to females (W). We found evidence that the same ZW-ZZ mechanism is common in both Atlantic and Pacific subspecies of salmon lice using PCR assays. The W chromosome was approximately 800 kb in size, which is ∼30 times smaller than the Z chromosome (24 Mb). The W chromosome contained 61 annotated genes, including 32 protein-coding genes, 27 long noncoding RNA (lncRNA) genes, and 2 pseudogenes. Among these 61 genes, 39 genes shared homology to genes found on other chromosomes, while 20 were unique to the W chromosome. Two genes of interest on the W chromosome, prohibitin-2 and kinase suppressor of ras-2, were previously identified as potential sex-linked markers in the salmon louse. However, we prioritized the 20 unique genes on the W chromosome as sex-determining candidates. This information furthers our understanding of the biology of this ectoparasite and may help in the development of more effective management strategies.

Wild salmon migration routes influence sea lice infestations: An agent-based model predicting farm-related infestations on juvenile salmon.

This study presents an Agent-Based Model (ABM) simulation to assess the impact of varying migration routes on sea lice (Caligus clemensi) infestation levels in juvenile wild sockeye salmon (Oncorhynchus nerka) in the Discovery Islands, British Columbia, Canada. This research highlights the importance of migratory routes in determining the extent of exposure to sea lice originating from nearby salmon farms. Three northward out-migration routes were modelled, each exposing the fish to different levels of infestation pressure based on proximity to salmon farms. The ABM incorporates spatially explicit migration patterns of juvenile sockeye salmon using a detailed raster map of the Discovery Islands. Key variables such as swimming speed, progression rate, and infestation levels were integrated into the model, offering a comprehensive analysis of migration and infestation dynamics. The study revealed that infestation rate is highly variable, depending on migration routes. Specifically, salmon traveling longer migration routes with lower infestation pressure may experience higher sea lice loads compared to those on shorter routes with higher infestation pressure. This underscores the role of low infestation pressures and the critical influence of swimming speed, which affects exposure time, and thus infestation rates. Additionally, the study conducted a sensitivity analysis to understand the influence of various parameters on infestation rates. This analysis highlighted the importance of swimming speed and progression rate, particularly in routes closer to the farms. The findings suggest that slower swimming speeds and meandering routes increase exposure to lice, thereby elevating infestation levels. The research contributes to understanding the dynamics of sea lice transmission and its relationship with salmon migration patterns. It underscores the necessity of considering migratory routes and farm proximity in managing and mitigating the impact of sea lice infestation on wild salmon populations. This study's insights are crucial for developing strategies to balance aquaculture practices with the conservation of wild salmon.

Consequences of reduced effectiveness of salmon lice treatments for lice control.

The effective control of ectoparasitic salmon lice, Lepeophtheirus salmonis, in fish farms is challenged by the salmon lice having developed resistance towards several antiparasitic drugs and by the effectiveness of non-medicinal treatments being limited by considerations of fish welfare. When new antiparasitics are introduced to the market, these should be used sparingly to slow resistance development. Using a population model for salmon lice parameterised for salmonid fish farms in Norway, we quantified how reduced treatment effectiveness influences treatment frequency and lice abundance. Furthermore, we investigated when in the production cycle a highly effective lice treatment leads to the largest reduction in the total number of treatments, mean lice abundance and lice larvae production. Results showed that reductions in treatment effectiveness to lower than 50% led to the steepest increases in treatment frequency and mean lice abundance, as well as to increased risk that lice abundance increased beyond control. The timing of the most effective treatment had only moderate effects on the total treatment need and the mean number of adult female lice through the production cycle, but large effect on the production of lice larvae in spring. These findings imply that farmers can optimise the timing of the most effective treatment to reduce the release of lice larvae in the period of year when wild salmonids are in coastal waters, without compromising total treatment need or mean lice levels.

Effects of regional coordination of salmon louse control in reducing negative impacts of salmonid aquaculture on wild salmonids.

Parasitic salmon lice (Lepeophtheirus salmonis) are a constraint to the sustainable growth of salmonids in open net pens, and this issue has caused production to level off in recent years in the most aquaculture-intensive areas of Norway. The maximum allowed biomass at a regional level is regulated by using the so-called "traffic light" system, where salmon louse-induced mortality of migrating wild salmon post-smolts is evaluated against set targets. As a case study, we have investigated how a specific aquaculture-intensive area can reduce its louse levels sufficiently to achieve a low impact on wild salmon. Analyses of the output from a virtual post-smolt model that uses data on the reported number of salmon lice in fish farms as key input data and estimates the salmon louse-induced mortality of wild out-migrating Atlantic salmon post-smolts, suggested that female louse abundance on the local farms must be halved in spring to reach the goal implied by the traffic light system. The outcome of a modelling scenario simulating a proposed new plan for coordinated production and fallowing proved beneficial, with an overall reduction in louse infestations and treatment efforts. The interannual variability in louse abundance in spring, however, increased for this scenario, implying unacceptably high louse abundance when many farms were in their second production year. We then combined the scenario with coordinated production with other louse control measures. Only measures that reduced the density of farmed salmonids in open cages in the study area resulted in reductions in salmon louse infestations to acceptable levels. This could be achieved either by stocking with larger fish to reduce exposure time or by reducing fish numbers, e.g. by producing in closed units.

Ocorrência de Vibrio parahaemolyticus e Salmonella spp. em “sashimis” comercializados em restaurantes no município do Rio de Janeiro / Occurrence of Vibrio parahaemolyticus and Salmonella spp. in sashimi commercialized in restaurants at the city Rio de Janeiro

Visando conhecer a segurança do produto "sashimi" de salmão fornecido em restaurantes, e dos riscos potenciais ao consumidor, a pesquisa objetivou avaliar a ocorrência de Vibrio parahaemolyticus e de Salmonella spp na matéria-prima, no produto final antes de sua exposição à venda e após sua exposição ao cliente; e de Salmonella spp nas mãos dos manipuladores, em dois restaurantes (RI e RII). Os estabelecimentos foram classificados pelas diferentes condições de higiene e climatização do ambiente de manipulação, sendo RII considerado o melhor. Foi verificada a ausência de Vibrio parahaemolyticus em 100% das amostras; presença de Salmonella spp. em 12,5% do total de amostras analisadas, sendo todas estas pertencentes a RII: 25% estava presente na mão do manipulador e 75%, presente na matéria-prima e produtos finais. Através dos resultados da pesquisa pôde-se concluir que ambos os estabelecimentos estavam em conformidade com a RDC 12 de 2001 da ANVISA para Vibrio parahaemolyticus, mas RII enquadrou-se fora dos padrões estabelecidos quanto à presença de Salmonella spp. O resultado sugere que RII necessita da adoção eficaz de práticas higiênicosanitárias na elaboração de "sashimi" para eliminar a presença de Salmonella spp., que é um risco potencial à saúde do consumidor.

In order to know the quality and safety of the sashimi salmon comes in restaurants and its potential risks to the consumer, this research aimed evaluated the occurrence of Vibrio parahaemolyticus and Salmonella in raw material, on the final product before its exposure to sales and after exposure to the client and Salmonella spp in the hands of handlers, in two restaurants (RI and RII). The difference between the places was classified by the conditions of environmental air handling and hygiene, and RII was considered the best. It was verified the absence of Vibrio parahaemolyticus in 100% of samples, the presence of Salmonella spp. in 12.5% of total samples analyzed, with absence in all samples of RI and presence in 25% of samples at RII. In this proven contamination, 25% was present in the hands of the handlers and 75% present in the raw material and finished products. Based on the results of research it was concluded that both establishments were in compliance with the legislation for the first microorganism, but RII, although had the best conditions of climate and hygiene, framed outside of the microbiological standards established by the presence of Salmonella spp. The results suggest that the establishment in violation of the law requires the efficient and effective adoption of adequate sanitary practices in preparation of sashimi to avoid the presence of Salmonella spp., which can pose a risk to consumer health.

Acuicultura y salud pública: La expansión de la difilobotriasis en Chile y el mundo / Aquaculture and public health: The emergence of diphyllobothriasis in Chileand the world

Recent clinical and epidemiológica! information, an analysis of the literature, and study of the technical aspects of Chilean salmon aquaculture indicate that this activity has the ability to expand the range of diphyllobothriasis caused by the fish tapeworm Diphyllobothrium latum. Evidence for expansion of the range of the fish tapeworm includes the emergences of clinical cases in Brazil related to consumption of salmon produced in Chile. Expansion of the range of this parasite is also suggested by an increase of its geographical range in Chile, beyond its previously endemic foci in the lakes of Regions IX and X. Prevention of further dissemination of this parasitic disease rests on an improvement of sanitation and sewage disposal around the lakes of Regions IX, X and XI in Chile, improvement in aquaculture methods including curtailing the use offish tapeworm-contaminated lakes to grow juveniles forms ofsalmonids and more measures to decrease the number of salmonid escapees from marine pens to prevent their return to rivers and lakes carrying the infestation. Moreover, tracking the origin ofjuveniies in marketed salmon, determining the presence of plerocercoids in them, and increased education of the public regarding the potential dangers of eating raw fish should also be implemented. Only by stimulating the dialogue between the industry, consumers and state regulators will it be possible to implement appropriate measures to prevent further expansion of this parasitic disease by salmon aquaculture.

Difilobotríase: atualidades e perspectivas / Diphyllobothriasis: updates and perspectives

A difilobotríase é uma moléstia intestinal provocada por cestódeos do gênero Diphyllobothrium (tênia) que até pouco tempo havia poucos relatos em nosso país. Porém, em decorrência do aumento do consumo de peixes crus, mal cozidos ou defumados e da falta de cuidado nos seus preparos, vêm sendo identificados casos autóctones no Brasil. O número de pessoas parasitadas pelo platelminto difilobotríase, presente em várias regiões do mundo, vem aumentando desde 2003. A doença pode ser assintomática ou causar desconforto abdominal e interferir na absorção da vitamina B12, podendo causar anemia megaloblástica. Abster-se do consumo de pescado cru, defumado em temperaturas inadequadas ou mal cozido é a principal medida para a sua prevenção.

The intestinal diphyllobotriasis is a disease caused by Diphyllobothrium (cestodes of the genus Taenia [tapeworm]) that until recently had a few reports in our country. However, as a result of increased consumption of raw fish, soft-boiled or smoked and lack of care in their staging have been identified indigenous cases in Brazil. The number of people by the flatworm diphyllobotriasis parasitized, present in various regions of the world, comes increasing since 2003. The disease may be asymptomatic or cause abdominal discomfort and interferes in the absorption of vitamin B12, leading to megaloblastic anemia. Avoid from eating raw, smoked or soft-boiled fish is the primaries beware of their prevention.

Epidemiología de la difilobotriasis en la cuenca del río Valdivia, Chile / Epidemiology of diphyllobothriasis in the Valdivia River basin, Chile

Foram examinadas 1.295 pessoas de seis localidades situadas às margens da bacia do rio Valdivia (Chile), encontrando-se uma prevalência de infecçäo por Diphyllobothrium igual a 1,2% em Rinihue e Las Huellas. Em cäes a prevalência foi de 5,3% e 9,8% em Rinihue e Malihue, respectivamente, näo tendo sido observada infecçäo em gatos nem porcos. Os parasitas obtidos apòs tratamento foram identificados como Diphyllobothrium latum. A infecçäo humana por Diphyllobothrium latum nas áreas afetadas foi produzida pela ingestäo de peixes defumados ou cozidos insuficientemente. A pesquisa realizada em 1.450 peixes pertencentes a 4 espécies introduzidas e 11 autoctones capturadas na bacia do rio Valdivia mostrou a existência de plerocercoides de Diphyllobothrium latum e/ou D. dendriticum nas espécies introduzidas Salmo gairdneri e S. trutta além de outras autoctones. A prevalência ou intensidade média das infecçöes nos peixes bem como o grau de agregaçäo das subpopulaçöes variaram nos diferentes locais estudados. Na bacia do rio Valdivia, alguns peixes atuaram como hospedeiros intermediários e outros como paratênicos das espécies de Diphyllobothrium encontradas. Como medidas de controle nos pontos de difilobotríase nas áreas estudadas sugere-se a melhoria das condiçöes de saneamento básico, educaçäo sanitária e tratamento das pessoas infectadas .

Registro de nuevos casos de difilobotriasis humana en Chile (1981-1992), incluído un caso de infección múltiple por diphyllobothrium latum / Record of new cases of human diphyllobothriasis in Chile (1981-1992), including a case of multiple diphyllobotrium latum infection

New records of human diphyllobothriasis in Chile (1981-1992), with a case of multiple diphyllobotrium latum infection

Quantitative evaluation of Clostridium botulium nonproteolytic types B, E and F growth risk in fresh salmon store under modified atmospheres

This dissertation is composed of three papers. In the first paper, the prevalence of residential C. botulium in fish and other seafood sold at Davis supermarkets was examined. Prevalence ranged from 0-100%. Although C. botulium types A, B, E and F were detected, type A was predominant. Estimated MPN number in red snapper ranged from 0.9-2.4 and 0.03 to 1.2 organism/g fish, respectively. In the second paper, the suitability of using salmon tissue muscle homogenates (microsystem) as asubstrate for evaluation of nonproteolytic C. botulium growth risk was studied. Using factorial desing experiments and regression approach, the effect and interactions of variables such as temperature, storage time, spore inocolum level, initial microbial fish flora and type of modified atmosphere (MA) on the probability (P) of C. botulium growth and toxigenesis was examines. Several models for estimation of the length of the lag phase (LP) and the probability (P) of growth and toxigenesis by one nonproteolytic spore under a particular storage condition were developed. In the last paper, the risk of C. botulium growth and toxin production in fresh salmon fillets was evaluated. Regression equations were derived to estimate LP and P of toxigenesis. A close agreement between the LPS and Ps estimated in the microsystem and the fillets demonstrated the feasibility of the quantitative approach and the utility of the microsytem for risk analysis. A narrow margin safety existed in fish stored under MA when it was held at slightly abused temperatures