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Aquaculture has grown tremendously due to the big demand for its products. However, diseases affecting aquaculture and economic losses are worldwide problems and it needs low cost, sustainable, highly efficient, specific and eco-friendly therapeutants. Due to the rising up antibiotic resistant-microorganism, bacteriophage therapy has reinvigorated to replace antibiotics in agriculture, medicine, food safety and the environment. Likewise, it also holds great promise to avoid, control and treat bacteria in aquaculture to decrease the mortality level of different aquatic animal diseases. The isolation and characterization of new phages and phage application therapy to eliminate bacterial fish and shellfish pathogens such as Vibrio, Aeromonas, Pseudomonas, Lactococcus, Yersinia, Flavobacterium, and Streptococcus was gradually reported in aquaculture literature. The present review summarizes large-scale reports in vitro or in vivo use of aquaphage studies and applications in fish diseases from the 1980s to 2022 and future directions.

Flavobacterial diseases, caused by bacteria in the order Flavobacteriales, are responsible for devastating losses in farmed and wild fish populations worldwide. The genera Flavobacterium (Family Flavobacteriaceae) and Chryseobacterium (Weeksellaceae) encompass the most well-known agents of fish disease in the order, but the full extent of piscine-pathogenic species within these diverse groups is unresolved, and likely underappreciated. To identify emerging agents of flavobacterial disease in US aquaculture, 183 presumptive Flavobacterium and Chryseobacterium isolates were collected from clinically affected fish representing 19 host types, from across six western states. Isolates were characterized by 16S rRNA gene sequencing and phylogenetic analysis using the gyrB gene. Antimicrobial susceptibility profiles were compared between representatives from each major phylogenetic clade. Of the isolates, 52 were identified as Chryseobacterium species and 131 as Flavobacterium. The majority of Chryseobacterium isolates fell into six clades (A-F) consisting of ≥ 5 fish isolates with ≥ 70% bootstrap support, and Flavobacterium into nine (A-I). Phylogenetic clades showed distinct patterns in antimicrobial susceptibility. Two Chryseobacterium clades (F & G), and four Flavobacterium clades (B, G-I) had comparably high minimal inhibitory concentrations (MICs) for 11/18 antimicrobials tested. Multiple clades in both genera exhibited MICs surpassing the established F. psychrophilum breakpoints for oxytetracycline and florfenicol, indicating potential resistance to two of the three antimicrobials approved for use in finfish aquaculture. Further work to investigate the virulence and antigenic diversity of these genetic groups will improve our understanding of flavobacterial disease, with applications for treatment and vaccination strategies.

The Gram-negative bacterium A. salmonicida is the causal agent of furunculosis and used to be one of the most loss-causing bacterial infections in the salmonid aquaculture industry with a mortality rate of about 90% until the 1990s, when an inactivated vaccine with mineral oil as adjuvant was successfully implemented to control the disease. However, the use of this vaccine is associated with inflammatory side effects in the peritoneal cavity as well as autoimmune reactions in Atlantic salmon, and incomplete protection has been reported in rainbow trout. We here aimed at developing and testing a recombinant alternative vaccine based on virus-like particles (VLPs) decorated with VapA, the key structural surface protein in the outer A-layer of A. salmonicida. The VLP carrier was based on either the capsid protein of a fish nodavirus, namely red grouper nervous necrotic virus (RGNNV) or the capsid protein of Acinetobacter phage AP205. The VapA and capsid proteins were expressed individually in E. coli and VapA was fused to auto-assembled VLPs using the SpyTag/SpyCatcher technology. Rainbow trout were vaccinated/immunized with the VapA-VLP vaccines by intraperitoneal injection and were challenged with A. salmonicida 7 weeks later. The VLP vaccines provided protection comparable to that of a bacterin-based vaccine and antibody response analysis demonstrated that vaccinated fish mounted a strong VapA-specific antibody response. To our knowledge, this is the first demonstration of the potential use of antigen-decorated VLPs for vaccination against a bacterial disease in salmonids.

Tenacibaculum maritimum is a devastating bacterial pathogen affecting a large variety of marine fish species. It is responsible for significant economic losses in aquaculture farms worldwide. Different typing methods have been proposed to analyze bacterial diversity and population structure. Serological heterogeneity has been observed and up to four different serotypes have been described so far. However, the underlying molecular factors remain unknown. By combining conventional serotyping and genome-wide association study, we identified the genomic loci likely involved in the O-antigen biosynthesis. This finding allowed the development of a robust multiplex PCR-based serotyping scheme able to detect subgroups within each serotype and therefore performs better than conventional serotyping. This scheme was successfully applied to a large number of isolates from worldwide origin and retrieved from a large variety of fish species. No obvious correlations were observed between the mPCR-based serotype and the host species or the geographic origin of the isolates. Strikingly, the distribution of mPCR-based serotypes does not follow the core-genome phylogeny. Nevertheless, this simple and cost-effective mPCR-based serotyping method could be useful for different applications such as population structure analysis, disease surveillance, vaccine formulation and efficacy follow-up.

Tenacibaculum maritimum is a devastating bacterial pathogen affecting a large variety of marine fish species. It is responsible for significant economic losses in aquaculture farms worldwide. Different typing methods have been proposed to analyze bacterial diversity and population structure. Serological heterogeneity has been observed and up to four different serotypes have been described so far. However, the underlying molecular factors remain unknown. By combining conventional serotyping and genome-wide association study, we identified the genomic loci likely involved in the O-antigen biosynthesis. This finding allowed the development of a robust multiplex PCR-based serotyping scheme able to detect subgroups within each serotype and therefore performs better than conventional serotyping. This scheme was successfully applied to a large number of isolates from worldwide origin and retrieved from a large variety of fish species. No obvious correlations were observed between the mPCR-based serotype and the host species or the geographic origin of the isolates. Strikingly, the distribution of mPCR-based serotypes does not follow the core-genome phylogeny. Nevertheless, this simple and cost-effective mPCR-based serotyping method could be useful for different applications such as population structure analysis, disease surveillance, vaccine formulation and efficacy follow-up.

Cyanobacteria (blue-green algae) have been present on Earth for over 2 billion years, and can produce a variety of bioactive molecules, such as cyanotoxins. Microcystins (MCs), the most frequently detected cyanotoxins, pose a threat to the aquatic environment and to human health. The classic toxic mechanism of MCs is the inhibition of the protein phosphatases 1 and 2A (PP1 and PP2A). Immunity is known as one of the most important physiological functions in the neuroendocrine-immune network to prevent infections and maintain internal homoeostasis in fish. The present review aimed to summarize existing papers, elaborate on the MC-induced immunotoxicity in fish, and put forward some suggestions for future research. The immunomodulatory effects of MCs in fish depend on the exposure concentrations, doses, time, and routes of exposure. Previous field and laboratory studies provided strong evidence of the associations between MC-induced immunotoxicity and fish death. In our review, we summarized that the immunotoxicity of MCs is primarily characterized by the inhibition of PP1 and PP2A, oxidative stress, immune cell damage, and inflammation, as well as apoptosis. The advances in fish immunoreaction upon encountering MCs will benefit the monitoring and prediction of fish health, helping to achieve an ecotoxicological goal and to ensure the sustainability of species. Future studies concerning MC-induced immunotoxicity should focus on adaptive immunity, the hormesis phenomenon and the synergistic effects of aquatic microbial pathogens.

Several biocides are widely used in rainbow trout aquaculture against various ectoparasites and ectobionts, but the inflammation induced in treated fish is less well described. Dose-response studies were conducted to elucidate the effects on rainbow trout (gills and fins) induced by a series of biocides including formalin, hydrogen peroxide (H2O2), peracetic acid (PAA) and the surfactant SPH6, which was isolated from the bacterium Pseudomonas H6. The compounds have documented antiparasitic effects, but the specific effects on fish needs further documentation. This study was performed over 24 h, and inflammatory reactions were evaluated in gills and fins. A dose-dependent effect was noted for expression of immune genes encoding for IL-1β, TNFα, IFNγ, IL-10, IL-8, lysozyme, serum amyloid A (SAA), hepcidin, precerebellin and complement factor C3. PAA induced the strongest upregulation of cytokine and acute phase reactant genes followed by H2O2 and formalin. SPH6 showed a lower effect, and in several cases the compound induced downregulation of several genes. Gills showed a stronger response compared to fins. The mucous cell density in fins showed a range of changes which varied by compound. PAA, and to a lesser degree H2O2 and formalin, initially induced mucous cell hyperplasia, whereas SPH6 immediately decreased the number of cells containing mucus.

Modulation of brain serotonin (5-HT) signalling is associated with parasite-induced changes in host behaviour, potentially increasing parasite transmission to predatory final hosts. Such alterations could have substantial impact on host physiology and behaviour, as 5-HT serves multiple roles in neuroendocrine regulation. These effects, however, remain insufficiently understood, as parasites have been associated with both increased and decreased serotonergic activity. Here, we investigated effects of trematode Euhaplorchis californiensis metacercariae on post-stress serotonergic activity in the intermediate host California killifish (Fundulus parvipinnis). This parasite is associated with conspicuous behaviour and increased predation of killifish by avian end-hosts, as well as inhibition of post-stress raphe 5-HT activity. Until now, laboratory studies have only been able to achieve parasite densities (parasites/unit host body mass) well below those occurring in nature. Using laboratory infections yielding ecologically relevant parasite loads, we show that serotonergic activity indeed decreased with increasing parasite density, an association likely indicating changes in 5-HT neurotransmission while available transmitter stores remain constant. Contrary to most observations in the literature, 5-HT activity increased with body mass in infected fish, indicating that relationships between parasite load and body mass may in many cases be a real underlying factor for physiological correlates of body size. Our results suggest that parasites are capable of influencing brain serotonergic activity, which could have far-reaching effects beyond the neurophysiological parameters investigated here.

SHORT COMMUNICATION Infection by the fungus Ochroconis humicola causes mortality in juveniles of marine fish species including the marbled rockfish, Sebastiscus marmoratus, which is cultured in Japan (Munchan et al., 2006; Wada, Hanjavanit, Kurata, & Hatai, 2005; Wada, Nakamura, & Hatai, 1995). Erosive or ulcerative features on the body surface, especially skin lesions on the head, have been reported as the major clinical signs of O. humicola infection in Japanese marine cultured fish (Wada et al., 2005, 1995). These case reports suggest that O. humicola consistently infects younger fish. For example, Wada et al. (2005) recorded infections in juvenile marbled rockfish weighing about 1 g. However, there have not yet been any studies investigating the occurrence of O. humicola infection in relation to fish age. Therefore, our objective was to examine the association between susceptibility to infection and age of marbled rockfish.

The impact of acute and chronic marine pollution on the population changes of individual fish remains mostly unknown. In this paper, we share our study and review similar published work, emphasising fish health monitoring in European Seas and illustrating it using case studies. Arguably, an integrative approach is needed to assess the impact on population of chemical contaminants, beginning with field observations and complemented with experimental (laboratory and mesocosm) studies and modelling. Field surveys and monitoring using fish biomarkers should be intensified and ideally integrated with population statistics and fish ecology knowledge. Moreover, the indirect effects of chemicals – altering ecosystem functions – and the monitoring of immunological biomarkers and fatal diseases in wild fish populations should receive more attention

The impact of acute and chronic marine pollution on the population changes of individual fish remains mostly unknown. In this paper, we share our study and review similar published work, emphasising fish health monitoring in European Seas and illustrating it using case studies. Arguably, an integrative approach is needed to assess the impact on population of chemical contaminants, beginning with field observations and complemented with experimental (laboratory and mesocosm) studies and modelling. Field surveys and monitoring using fish biomarkers should be intensified and ideally integrated with population statistics and fish ecology knowledge. Moreover, the indirect effects of chemicals – altering ecosystem functions – and the monitoring of immunological biomarkers and fatal diseases in wild fish populations should receive more attention.

The impact of acute and chronic marine pollution on the population changes of individual fish remains mostly unknown. In this paper, we share our study and review similar published work, emphasising fish health monitoring in European Seas and illustrating it using case studies. Arguably, an integrative approach is needed to assess the impact on population of chemical contaminants, beginning with field observations and complemented with experimental (laboratory and mesocosm) studies and modelling. Field surveys and monitoring using fish biomarkers should be intensified and ideally integrated with population statistics and fish ecology knowledge. Moreover, the indirect effects of chemicals – altering ecosystem functions – and the monitoring of immunological biomarkers and fatal diseases in wild fish populations should receive more attention.

The impact of acute and chronic marine pollution on the population changes of individual fish remains mostly unknown. In this paper, we share our study and review similar published work, emphasising fish health monitoring in European Seas and illustrating it using case studies. Arguably, an integrative approach is needed to assess the impact on population of chemical contaminants, beginning with field observations and complemented with experimental (laboratory and mesocosm) studies and modelling. Field surveys and monitoring using fish biomarkers should be intensified and ideally integrated with population statistics and fish ecology knowledge. Moreover, the indirect effects of chemicals – altering ecosystem functions – and the monitoring of immunological biomarkers and fatal diseases in wild fish populations should receive more attention.

BackgroundInfectious hematopoietic necrosis (IHN) is a disease of salmonid fish that is caused by the IHN virus (IHNV). Under intensive aquaculture conditions, IHNV can cause significant mortality and economic losses. Currently, there is no proven and cost-effective method for IHNV control. Clear Springs Foods, Inc. has been applying selective breeding to improve genetic resistance to IHNV in their rainbow trout breeding program. The goals of this study were to elucidate the genetic architecture of IHNV resistance in this commercial population by performing genome-wide association studies (GWAS) with multiple regression single-step methods and to assess if genomic selection can improve the accuracy of genetic merit predictions over conventional pedigree-based best linear unbiased prediction (PBLUP) using cross-validation analysis.ResultsTen moderate-effect quantitative trait loci (QTL) associated with resistance to IHNV that jointly explained up to 42% of the additive genetic variance were detected in our GWAS. Only three of the 10 QTL were detected by both single-step Bayesian multiple regression (ssBMR) and weighted single-step GBLUP (wssGBLUP) methods. The accuracy of breeding value predictions with wssGBLUP (0.33-0.39) was substantially better than with PBLUP (0.13-0.24).ConclusionsOur comprehensive genome-wide scan for QTL revealed that genetic resistance to IHNV is controlled by the oligogenic inheritance of up to 10 moderate-effect QTL and many small-effect loci in this commercial rainbow trout breeding population. Taken together, our results suggest that whole genome-enabled selection models will be more effective than the conventional pedigree-based method for breeding value estimation or the marker-assisted selection approach for improving the genetic resistance of rainbow trout to IHNV in this population.

BACKGROUND:Drug-resistant fish pathogens can cause significant economic loss to fish farmers. Since 2012, florfenicol has become an approved drug for treating both septicemia and columnaris diseases in freshwater fish. Due to the limited drug options available for aquaculture, the impact of the therapeutical florfenicol treatment on the microbiota landscape as well as the resistome present in the aquaculture farm environment needs to be evaluated. RESULTS:Time-series metagenomic analyses were conducted to the aquatic microbiota present in the tank-based catfish production systems, in which catfish received standard therapeutic 10-day florfenicol treatment following the federal veterinary regulations. Results showed that the florfenicol treatment shifted the structure of the microbiota and reduced the biodiversity of it by acting as a strong stressor. Planctomycetes, Chloroflexi, and 13 other phyla were susceptible to the florfenicol treatment and their abundance was inhibited by the treatment. In contrast, the abundance of several bacteria belonging to the Proteobacteria, Bacteroidetes, Actinobacteria, and Verrucomicrobia phyla increased. These bacteria with increased abundance either harbor florfenicol-resistant genes (FRGs) or had beneficial mutations. The florfenicol treatment promoted the proliferation of florfenicol-resistant genes. The copy number of phenicol-specific resistance genes as well as multiple classes of antibiotic-resistant genes (ARGs) exhibited strong correlations across different genetic exchange communities (p < 0.05), indicating the horizontal transfer of florfenicol-resistant genes among these bacterial species or genera. Florfenicol treatment also induced mutation-driven resistance. Significant changes in single-nucleotide polymorphism (SNP) allele frequencies were observed in membrane transporters, genes involved in recombination, and in genes with primary functions of a resistance phenotype. CONCLUSIONS:The therapeutical level of florfe

Parasites in fish are ecological indicators, as they reflect the host's migration routes, feeding behavior and immune status. We performed a parasitological investigation of sea-running Baltic salmon to study the use of parasites as indicators for this fish stock. The host-a strain of Atlantic salmon Salmo salar-has been isolated for several millennia in the semi-enclosed brackish Baltic Sea, with limited migration to and from the North Sea. Twenty-four salmon (total body weight: 4.2-14.2 kg; total body length: 80-105 cm) were caught by spoon bait in the southern Baltic Sea during feeding migrations, necropsied shortly afterwards and internal organs subjected to parasitological investigation focusing on endoparasitic helminths. The pyloric region was heavily parasitized by the cestode Eubothrium crassum (100% prevalence; intensity: 97-273 parasites per infected fish), reflecting a diet of smaller pelagic fishes. The stomach contained the hemiurid digeneans Brachyphallus crenatus (95.8% prevalence; intensity: 8-151) and Hemiurus luehei (58.3% prevalence; intensity: 2-13), indicating a diet of clupeids. Schistocephalus solidus (25% prevalence; intensity: 1-2), liberated from ingested sticklebacks, the acanthocephalan Echinorhynchus truttae (54% prevalence; intensity: 1-13) and the adult nematode Hysterothylacium aduncum (29% prevalence; intensity: 1-13) were found in the intestine. The liver was parasitized by third-stage nematode larvae of Contracaecum osculatum (45.8% prevalence; intensity: 1-4), but these were growth-stunted and encapsulated. The parasite fauna differs markedly from salmon in North Atlantic waters, and the lack of purely marine parasite species indicates that the Baltic salmon has remained in the Baltic Sea during its life history.

Myanmar is one of the OIE members and the Department of Fisheries (DoF) is highly concerned with transboundary aquatic animal pathogens. Therefore, the Aquatic Animal Health & Disease Control Section has already been formed not only for field diagnostic surveys but also for border control especially at international airport and border trade areas by checking and counter checking export and import of aquatic animals and products. At the moment, the DoF is stressing an issue of some transboundary diseases for finfish such as Gyrodactylus sp., Dactylogyrus sp., Argulus sp., Trichodena sp., Streptococcus sp., Aeromonas sp., and for crustacean are MrNV/XSV and WSSV. In addition, the DoF is facing challenges with parasitic disease and bacterial disease problems due to poor water quality management at culturing fish ponds. For the prevention and control of fish diseases within the country, the DoF is issuing Health Certificates by physical and microbiological examination of fishes and fisheries products. At the same time, Quarterly report on fish disease has being regularly submitted to NACA, OIE since 1998 until now. Although the DoF has no specific law and legislation on the control of quarantine pest and disease of aquatic animal, a good aquaculture practice has been implemented and code of conduct responsible for aquaculture is being followed in the country. The aquatic health management is a challenging issue in aquaculture development. Myanmar is still needing technical assistance to improve quarantine system especially for importation and exportation of live aquatic animals. Moreover, monitoring and surveillance programs with harmonized aquatic emergency preparedness and response system are required to boost up not only for Myanmar but also for effective management of transboundary disease outbreaks in Southeast Asia.

In Thailand, Department of Fisheries (DoF) is the competent authority for various aspects of aquatic animals including aquatic animal health. There are two principal legislation giving DoF power to apply for aquatic animal disease prevention and control measures in the country as well as import-export control; namely, Royal Ordinance on Fisheries and Animal Epidemic Act. DoF has two national reference laboratories for aquatic animal health, one is Aquatic Animal Health Research and Development Division (AAHRDD) for freshwater aquatic animal disease diagnosis and another is Songkhla Aquatic Animal Health Research Center (SAAHRC) for brackish water aquatic animal disease diagnosis. Both are ISO/IEC 17025 accredited laboratories. Besides, there are 19 regional laboratories of DoF located in different areas of the country. All of 21 laboratories are responsible for performing disease diagnosis service for fish farmers as well as for disease surveillance. There are a number of surveillance and control programs for aquatic animal diseases in Thailand. Passive surveillance: information can be collected from disease reporting and other sources such as scientific research, news, publications, social network, or rumor. Active surveillance: to provide assurance of disease status for trade purposes, DoF has setup nationally active targeted surveillance program for demonstrating a number of diseases free status of country or farm establishment in accordance with OIE Aquatic Animal Health Code. There are several farm standards in Thailand such as Good Aquaculture Practices for Hatchery of Disease Free Pacific White Shrimp, Good Aquaculture Practices for Marine Shrimp Farm, and Aquaculture Establishment for Export of Aquatic Animals. Each standard includes necessary biosecurity practices in order to prevent the introduction of pathogenic agent into or spread within or release from the farm. To control domestic movement of live aquatic animals, in normal situation, Aquatic Animal M

The Bureau of Fisheries and Aquatic Resources (BFAR) of the Department of Agriculture as the Competent Authority, develops and implements rules and regulations on aquatic animal health for the Philippines. It establishes the monitoring system for OIE/NACA listed aquatic animal diseases. The disease surveillance and reporting activities are being carried out by the BFAR Fish Health Laboratory of the National Fisheries Laboratory Division and its counterparts at the regional offices. BFAR Fish Health Laboratories have different levels of diagnostic and detection capabilities for aquatic animal diseases. Diagnostic services and technical assistance are rendered to farmers on aquatic animal health. Results of diagnostic services and surveillance by BFAR central and regional offices, and other laboratories (SEAFDEC/AQD-Fish Health, DA-Biotech, Negros Prawn Cooperative) are part of the country s aquatic animal disease reports to the OIE/NACA. BFAR has a Fish Health Network that responds to aquatic animal disease emergencies. It also coordinates and collaborates through networking with research agencies, academe, private sectors and other stakeholders on aquatic animal health. The Fisheries Inspection and Quarantine Division implements the policies on biosecurity, quarantine and health certification for trade and transboundary movement of aquatic animals. It is also responsible for risk analysis on the importation of fish and fishery/aquatic products. Other regulatory requirements for in-country movement include local transport permit for fish and fishery/aquatic products for traceability. Importers and exporters are also registered by BFAR to ensure compliance to sanitary and food safety measures and requirements. BFAR is continuously strengthening its technical capacity, human resources, policies and regulations for a more efficient implementation of aquatic animal health services that includes response to transboundary disease emergencies of aquatic animals.

Emergency preparedness is the ability to respond effectively and in a timely fashion to aquatic animal disease emergencies (e.g. disease outbreaks, mass mortalities). It is a key element of a National Strategy on Aquatic Animal Health and an important consideration of the Progressive Management Pathway for improving Aquaculture Biosecurity. The important principles, requirements and elements and components of emergency prepareness and contingency plans are briefly described. The emergency preparedness response system audit is also presented as contingency planning arrangements that can provide useful insights and guidance in improving response action to disease emergencies. The paper concludes that many important lessons and insights learned from dealing with disease epizootics in the early 2000 remains valid after more than two decades when the aquaculture sector continues to be plagued with emerging diseases. Past lessons and more recent experiences demonstrated the value of rapid response, reporting/notification by competent authorities, continuous development of knowledge base and capacities in diagnostics, epidemiology, risk analysis, advanced financial planning and the important roles of governments and producer sectors in co-managing disease outbreak events as they both remain the critical entities responsible for launching rapid response. Skills and knowledge need to be passed on to locals as they are in the frontline of any disease emergency. Share key lessons from experiences by state and non-state actors (producer and academic sectors and other important players in the value chain), the international players that launch emergency responses, disease investigations and field situation assessments as well as financial entities that support these actions need to be continued. However, we also need to do - a stock taking exercise to evaluate what worked, what did not work, what resources are needed and to understand what are the new drivers for aquatic animal

Aquaculture is one of the important sectors in the economy of most Asia-Pacific countries. However, majority of aquaculture farms are small-scale and most often lack the necessary facilities to comply with or are not well informed of the product standards imposed by concerned authorities, especially for international trade. Most countries in the region have a high reliance on aquatic animals as the major source of protein for their populations. In the past 20 years, farming of shrimp and fish for export has become a major employer and revenue earner for many countries in the region. Aquaculture is a major employer, contributes significantly to national economies, assists in poverty reduction, and is an important element in food security and other national development priorities. Aquaculture has developed rapidly in the region and is now a significant component in the national economies of many countries. However, recent disease events in fish and shrimp farming have indicated that preparedness and response measures are lacking, contributing to spread of disease across large areas of the countries involved. The growth of aquaculture in recent decades has been dependent on the international movement of aquatic animals and, in particular, the introduction of non-native species. The movement of live aquatic animals and their products has the potential to spread pathogens from one country or region to another, which may result to disease outbreaks. In shrimps as example, most major disease outbreaks were associated with the movement of live animals (broodstock, nauplii and postlarvae) when the patterns of disease spread were analyzed. Many aquatic animal diseases, once established, are often difficult to treat or to eliminate. Over the past 30 years, the Asia-Pacific region has been swept by a number of devastating diseases of aquatic animals which have caused massive economic and social losses. These include spread and outbreaks of infection with Aphanomyces invadans (E

Tilapia lake virus (TiLV) is a novel RNA virus resembling Orthomyxovirus. It has been recently re-classified to Tilapia tilapinevirus species, under Tilapinevirus genus, Amnoonviridae family (ICTV, 2018). Since the first discovery in Israel in 2014, so far TiLV has been reported from 14 countries in three continents (Asia, Africa, and South America). Thailand is one of the affected countries that reported emergence of this virus in 2017. Initially, we employed nested RT-PCR primer sequences previously published for TiLV diagnosis. However, the resulting amplification of nonspecific fish genes led us to modify the nested RT-PCR protocols into a semi-nested RT-PCR by omitting a non-specific primer to avoid false positive results. Subsequently, our molecular work together with histopathology and sequence analysis confirmed the presence of TiLV infection in Thailand. Prior to the publication of our manuscript, we informed the Thai Department of Fisheries of our discovery of TiLV in Thailand. Our publication was preceded by a brief article at the website of the Network of Aquaculture Centers in Asia-Pacific in which we warned of the spread of TiLV and offered free use of a newly improved, semi-nested RT-PCR method and positive control plasmid for detection of TiLV. To date, we have provided positive controls in response to 44 requests from 24 countries who have expressed their appreciation for our attempt to help in emergent controlling the spread of this fish pathogen. Our current study focuses on genetic diversity of TiLV and development of detection method that covers all genetic variants.

The purpose of this survey is to obtain information on national capacity and the agencies mandated to implement emergency preparedness and response systems with respect to aquatic animal diseases. The results of this survey will help guide regional and national strategic planning with respect to improving aquatic EPR systems, thereby improving aquatic animal health more broadly and assuring adequate and rational support services to achieve sustainable aquaculture development. This FAO questionnaire on aquatic EPR system capacity and performance is a country level self-assessment survey with four sections: (1) general administration, (2) operational components, (3) support systems and (4) additional information.

The regulatory authority responsible for the control of aquatic animal diseases in Japan is the Animal Products Safety Division, Food Safety and Consumer Affairs Bureau, Ministry of Agriculture, Forestry, and Fisheries (MAFF). The ministry (Animal Products Safety Division) specifies certain diseases and their host species that are subjects for import quarantine on the basis of the law called Fisheries Resources Protection Act. The MAFF also implements risk control measures for the same diseases within Japan on the basis of another law, Fish Farming Production Maintaining Act. Currently, 24 such diseases are listed. For disease control within Japan, the MAFF issues Guideline for the Control of Aquatic Animal Diseases, which states the roles of different stakeholders, appropriate actions that are to be taken on the occurrences of specified or other diseases, fish health guidelines for fish farmers, or diagnostic methods for specified diseases, etc. Local prefectural governments in Japan are required to place personnel who work on fish health issues at the prefectural fisheries research laboratories. These people usually inspect fish farms, observe cultured aquatic animals, supervise the use of antibiotics or vaccines, and guide fish farmers for disease control. Disease diagnosis for aquatic animals is usually conducted by these local fisheries research labs for free. The Japan Fisheries Resource Conservation Association provides a comprehensive training course on fish diseases including laws or hands-on trainings for the staff of prefectural fisheries research laboratories. The JFRCA also give local fish health personnel the qualification as the fish health expert, if the person passes the examination conducted after the training course. Primary diagnosis for specified diseases is conducted by local fisheries laboratories. On the occurrence of the diseases that are suspected to be one of the specified diseases or OIE listed diseases that have not been reported in Japa

Singapore s population-dense, urban environment presents a unique context for her increasingly important aquaculture industry. This paper provides an overview of Singapore s existing aquatic emergency preparedness and response systems, which have been constructed and refined by the Agri-Food and Veterinary Authority (AVA) in view of past experience with detections of pathogens of warmwater fish. These systems have been developed to fulfil Singapore s obligations as an OIE member country and AVA s duty to safeguard food security, animal and public health. As a trade and export hub, it is critical for Singapore to have timely detection and reporting of diseases which can have an impact on trade. Singapore also needs to balance the needs and perceptions of the multiple stakeholders using the limited space and resources in our island state. Finally, this paper outlines the current issues and gaps of Singapore s existing aquatic emergency preparedness and response systems.

The World Organisation for Animal Health (OIE) is the intergovernmental organisation responsible for improving animal health worldwide. It is recognised as a reference organisation by the World Trade Organization (WTO) to develop international standards for animal health and zoonoses; as of May 2018, it counts a total of 182 Members. As the global leader for animal health and welfare standards, the OIE plays an influential role in the prevention, control and information sharing of animal diseases including aquatic animal diseases. The objectives of OIE are to: (1) Ensure transparency in the global animal disease situation; (2) Collect, analyse and disseminate veterinary scientific information; (3) Encourage international solidarity in the control of animal diseases; (4) Safeguard World trade by publishing health standards for international, trade in animals and animal products; (5) Improve the legal framework and resources, national veterinary services and aquatic animal health services; and (6) to provide a better guarantee of food of animal origin and to promote animal welfare. As an international standard setting organisation, the OIE Aquatic Animal Health Code (the Aquatic Code) provides standards for the improvement of aquatic animal health worldwide. It also includes standards for the welfare of farmed fish and use of antimicrobial agents in aquatic animals. The sanitary measures in the Aquatic Code provide international standards on importing and exporting countries for early detection, reporting and control of pathogenic agents in aquatic animals (amphibians, crustaceans, fish and molluscs) and to prevent their spread via international trade in aquatic animals and their products, while avoiding unjustified sanitary barriers to trade. In addition, to provide a standardised approach to the diagnosis of the diseases listed in the Aquatic Code and to facilitate health certification for trade in aquatic animals and aquatic animal products, the OIE also developed

The Competent Authority (CA) on aquatic animal health in Indonesia is the Directorate Aquaculture Area Development and Fish Health of the Directorate General of Aquaculture (DGA) under the Ministry of Marine Affairs. CA is supported by national reference laboratories and professional human resources that are capable of fish disease diagnosis; as well as an established network with the farmers, trading association, and relevant stakeholders which are actively involved in national meetings, conferences, socialization of emerging diseases and policy and regulation. To control transboundary fish disease at national level, the government of Indonesia has a National Strategy on Aquatic Animal Health and Environment, which was developed by FAO under project of TCP/INS/3402: 2013-2015) collaboration with DGA, Ministry of Marine Affairs and Fisheries (MMAF). To strenghten the implementation of aquaculture in the country, the Indonesian Government issued President regulation Number 28 in 2017 which includes the implementation of fish health management as well as emergency response (Section VI, Article 60). To support the implementation of EPRS, Special Task Force Teams are formed by the Director General of Aquaculture. Stakeholders' participation is very important in the implementation of EPRS, such as a prompt report by fish farmers and extension officer to the upper level fisheries officers at district, provincial, and national level of any observed unusual mortality that indicates disease outbreaks. EPRS activities consist of emergency response on early warning (disease information, disease preventing guideline and regulation); early detection (surveillance, appointed diagnostic laboratory); and early response (collecting information, task force formation, public awareness). Standard Operational Procedures, and detection and control were done based on published scientific information available and guidelines from World Organisation for Animal Health (OIE), Network of Aquac

Viet Nam is one of the top worldwide producers of aquaculture products which accounts for about 22 percent of total agricultural GDP of Viet Nam. Recently, diseases have become the biggest challenge for global aquaculture development therefore the Vietnamese government has paid close attention to develop an effective aquatic emergency preparedness and response system to timely deal with disease introduction and outbreaks. The Department of Animal Health (DAH), under the Ministry of Agriculture and Rural Development (MARD), which is the competent authority of aquatic animal health management. To monitor transboundary diseases (especially the OIE-listed diseases), the current Vietnamese regulations only allow import of aquatic animals and its products which are certified as disease-free by competent authority of exporting country, and export aquatic animals and its products complying with importing conditions of importing country. Regional Animal Health Offices (belong to DAH) shall carry out sampling for testing pathogens and isolation for imported aquatic animals and its products as regulated in Circular 26/2016/TT-BNNPTNT dated 30 June 2016 before granting permit to import or export. For domestic transportation of aquatic animals, provincial sub DAH is responsible for monitoring infectious pathogens to certify disease-free status of aquatic animals before issuing health certificate for movement. In addition, a reporting and response system to aquatic animal diseases was established in the country from farm level to central level (DAH). Early detection and warning of diseases is critical for disease prevention and control, thus since 2014, the DAH has implemented national surveillance programs focusing on dangerous diseases in the key farming species (brackish-water shrimps, pangasius catfish) according to Circular 04/2016/TT-BNNPTNT dated 10 May 2016 of MARD and support exportation of aquatic animals and its products complying with international regulations and imp

The information presented in this paper were taken from several key FAO documents. The objective is to continuously raise awareness about the concept of risk analysis and its application to the aquaculture sector. The paper provides information in response to several key risk questions, e.g.: (1) what is risk versus hazard, (2) what is risk analysis, (3) who uses risk analysis, (4) why do countries need to be able to use risk analysis? An overview of the risks in aquaculture is also provided in terms of the process and approaches; and the different risk sectors in aquaculture. The paper concludes with some key points and challenges. Risk analysis is a decisionmaking tool that contributes to protecting national health and welfare. It can also contribute to sustainable aquaculture and the success of individual aquaculture businesses and operations. Risk analysis does not stand alone - it supports and is supported by other components of a National Strategy on Aquatic Animal Health. A basic strength of the risk analysis process is its flexibility - it is adaptable to almost any sector/system where risk and uncertainty occur. Countries will often be confronted with a lack of scientific information, both quality and quantity, to support the risk analysis process. Nevertheless, governments must often act under these uncertainties as well as make decisions in the face of a great deal of complexity, significant variability, and multiple management goals.

Parasites in fish are ecological indicators, as they reflect the host's migration routes, feeding behavior and immune status. We performed a parasitological investigation of sea-running Baltic salmon to study the use of parasites as indicators for this fish stock. The host-a strain of Atlantic salmon Salmo salar-has been isolated for several millennia in the semi-enclosed brackish Baltic Sea, with limited migration to and from the North Sea. Twenty-four salmon (total body weight: 4.2-14.2 kg; total body length: 80-105 cm) were caught by spoon bait in the southern Baltic Sea during feeding migrations, necropsied shortly afterwards and internal organs subjected to parasitological investigation focusing on endoparasitic helminths. The pyloric region was heavily parasitized by the cestode Eubothrium crassum (100% prevalence; intensity: 97-273 parasites per infected fish), reflecting a diet of smaller pelagic fishes. The stomach contained the hemiurid digeneans Brachyphallus crenatus (95.8% prevalence; intensity: 8-151) and Hemiurus luehei (58.3% prevalence; intensity: 2-13), indicating a diet of clupeids. Schistocephalus solidus (25% prevalence; intensity: 1-2), liberated from ingested sticklebacks, the acanthocephalan Echinorhynchus truttae (54% prevalence; intensity: 1-13) and the adult nematode Hysterothylacium aduncum (29% prevalence; intensity: 1-13) were found in the intestine. The liver was parasitized by third-stage nematode larvae of Contracaecum osculatum (45.8% prevalence; intensity: 1-4), but these were growth-stunted and encapsulated. The parasite fauna differs markedly from salmon in North Atlantic waters, and the lack of purely marine parasite species indicates that the Baltic salmon has remained in the Baltic Sea during its life history.

The aim of this study was to determine the changes in the mRNA transcription levels of HSP70 and IGF genes related to stress and immunity in Oncorhynchus mykiss obtained from fish farms, to determine the phenotypic and antimicrobial properties of the bacteria isolated in the study and to compare the results according to different diseases. Accordingly, six fish from each fish farm, a total of 30 fish were sampled. Bacterial identification, inoculations were carried out from the tissue samples taken from the kidney and symptomatic surfaces of fish samples in TSA. Primary cultures were obtained after incubation periods at 21 and 37oC. Gram staining, catalase, and oxidase tests were performed. Forty-six biochemical and 26 antimicrobial tests were performed using BD Phoenix ID Panels. Muscle tissue was used to determine mRNA gene expression differences and the tissues were preserved at -80°C in RNAlater storage solution. Following the RNA isolation and cDNA synthesis, a real-time PCR procedure was performed with b-Actin (ACTB), Insuline-like growth factor (IGF) and HSP70 Gene Primer Array system. Enterococcus faecium (E. faecium), Lactococcus garvieae (L. garvieae) and Staphylococcus aureus (S. aureus) agents were isolated in the study. These bacteria were identified with 91-99% similarity ratios. No disease agents in the gene expressions of the fish samples in were isolated and they were therefore used as controls. Compared to the control group, heat shock protein (HSP) mRNA expression was upregulated in fish tissues infected with E. faecium, S. aureus, and L. garvieae whereas no significant increase was determined in fish tissues infected with S. aureus. IGF mRNA gene expression was upregulated in all infected tissues. IGF expression was upregulated at the highest level in fish tissues infected with L. garvieae.

Historically, piscine francisellosis in various warm-, temperate-, and cold-water fish hosts has been attributed to Francisella noatunensis From 2015 to 2016, an undescribed Francisella sp. was recovered during mortality events in cultured spotted rose snapper (Lutjanus guttatus) off the Pacific coast of Central America. Despite high mortality and emaciation, limited gross findings were observed in affected fish. Histological examination revealed multifocal granulomatous lesions, with the presence of numerous small, pleomorphic coccobacilli, predominantly in the peritoneum, spleen, kidneys, liver, pancreas, heart, and intestine. Sequencing of an ∼1,400-bp fragment of the 16S rRNA gene demonstrated these isolates to be most similar (99.9% identity) to Francisella sp. isolate TX077308 cultured from seawater in the Gulf of Mexico, while sharing <99% similarity to other Fransicella spp. Biochemical analysis, multilocus sequence comparisons of select housekeeping genes, repetitive extragenic palindromic PCR fingerprinting, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and fatty acid methyl ester analysis revealed marked differences between these isolates and other described members of the genus. Koch's postulates were fulfilled by experimental intracoelomic injection and immersion trials using Nile (Oreochromis niloticus) and blue (Oreochromis aureus) tilapia. Based on observed phenotypic and genotypic differences from recognized Francisella spp., the name Francisellamarina sp. nov. (NRRL B-65518) is proposed to accommodate these novel strains.IMPORTANCE Finfish aquaculture is the fastest growing global food production sector. Infectious disease, particularly emergent pathogens, pose a significant threat to established and nascent aquaculture industries worldwide. Herein, we characterize a novel pathogen isolated from mortality events in cultured spotted rose snapper in Central America. The bacteria recovered from these outbreaks were g

Salmonid farming in Ireland is mostly organic, which implies limited disease treatment options. This highlights the importance of biosecurity for preventing the introduction and spread of infectious agents. Similarly, the effect of local network properties on infection spread processes has rarely been evaluated. In this paper, we characterized the biosecurity of salmonid farms in Ireland using a survey, and then developed a score for benchmarking the disease risk of salmonid farms. The usefulness and validity of this score, together with farm indegree (dichotomized as ≤ 1 or > 1), were assessed through generalized Poisson regression models, in which the modeled outcome was pathogen richness, defined here as the number of different diseases affecting a farm during a year. Seawater salmon (SW salmon) farms had the highest biosecurity scores with a median (interquartile range) of 82.3 (5.4), followed by freshwater salmon (FW salmon) with 75.2 (8.2), and freshwater trout (FW trout) farms with 74.8 (4.5). For FW salmon and trout farms, the top ranked model (in terms of leave-one-out information criteria, looic) was the null model (looic = 46.1). For SW salmon farms, the best ranking model was the full model with both predictors and their interaction (looic = 33.3). Farms with a higher biosecurity score were associated with lower pathogen richness, and farms with indegree > 1 (i.e. more than one fish supplier) were associated with increased pathogen richness. The effect of the interaction between these variables was also important, showing an antagonistic effect. This would indicate that biosecurity effectiveness is achieved through a broader perspective on the subject, which includes a minimization in the number of suppliers and hence in the possibilities for infection to enter a farm. The work presented here could be used to elaborate indicators of a farm's disease risk based on its biosecurity score and indegree, to inform risk-based disease surveillance and cont

Veronaea botryosa is a melanized mold and cause of systemic fungal infections in cultured sturgeon (Acipenser spp.). Mortality in adult female sturgeon caused by this emergent pathogen results in significant economic losses for the caviar industry. Little is known regarding environmental conditions conducive to V. botryosa infection. This study evaluated the effect of temperature on V. botryosa infectivity and dissemination following intramuscular injection challenge of white sturgeon maintained at 13 or 18 °C for 40 days. Daily mortality was recorded and persistence of the fungus in the livers of moribund and surviving fish was investigated using culture and histopathological analysis. Fish maintained at 18 °C developed systemic phaeohyphomycosis and had significantly greater mortality than controls and fish maintained at 13 °C (p < 0.05). Challenged fish, regardless of temperature, exhibited lesions in multiple organs. However, muscle lesions, angioinvasion, and systemic dissemination were more severe and widespread in fish challenged at the higher temperature. In vitro cytotoxicity of V. botryosa was evaluated in white sturgeon skin (WSSK-1) and epithelioma papulosum cyprini (EPC) cell lines inoculated at spore:cell ratios of 1:10, 1:1 and 10:1, then incubated 15, 20 and 25 °C. Cytotoxicity, as indicated by quantifying the release of lactate dehydrogenase into culture supernatants, increased with increasing spore dose and incubation temperature in both fish cell lines. Findings suggest that temperature significantly influences the development of systemic V. botryosa infection in white sturgeon and that WSSK-1 and EPC cells are suitable in vitro models for the study of host-pathogen interactions between V. botryosa and fish epithelial cells.

Background: Lernaea cyprinacea was introduced in South America with cyprinids. To the best of our knowledge, this ectoparasite has not been reported in Santa Fe province (Argentina). Objective: To report Lernaea cyprinacea presence in Rhamdia quelen under hatchery conditions in Santa Fe province (Argentina). Methods: In May 2014, samples of L. cyprinacea attached to the fins and flanks of R. quelen were obtained in the Chronobiology Laboratory of the Veterinary Sciences School at Esperanza (Santa Fe, Argentina) where they were collected and identified. Results: A description of L. cyprinacea is presented along with detailed records previously reported in this and other regions. Conclusions: Presence of this parasite constitutes evidence of the introduction of exotic species through commercialization of their natural hosts and the potential pathogen colonization of natural environments, which constitutes a threat to the integrity of aquatic ecosystems., Resumo Antecedentes: Lernaea cyprinacea foi introduzido na América do Sul através de ciprinídeos, não sendo registrado na província de Santa Fe. Objetivo: relatar a sua presença no Rhamdia quelen, em condições de crescimento. Método: em maio de 2014, foram obtidas individuos de L. cyprinacea, parasitando nadadeiras e flancos em R. quelen, no Cronobiologia Laboratório da Faculdade de Ciências Veterinárias, Esperanza (Santa Fe, Argentina), que foram coletados e identificados. Resultados: uma descrição de L. cyprinacea é relatada, e detalhes prévios da presença deste parasito na região. Conclusões: a presença neste parasito é evidência de introdução de espécies exóticas através da comercialização de seus hospedeiros naturais. O potencial de colonização de patógenos introduzidos em ambientes naturais é uma ameaça à integridade dos ecossistemas., Resumen Antecedentes: la Lernaea cyprinacea fue introducida en América del Sur a través de los ciprínidos, no habiendo siendo previamente registrada en la provincia de Santa Fe (Argentina). Objetivo: reportar la presencia de Lernaea cyprinacea en Rhamdia quelen en condiciones de acuicultivo. Método: en mayo de 2014, se obtuvieron ejemplares de L. cyprinacea, parasitando aletas y flancos de R. quelen en el laboratorio de Cronobiología de la Facultad de Ciencias Veterinarias, en Esperanza (Santa Fe, Argentina), donde fueron colectados e identificados. Resultados: se brinda una descripción de L. cyprinacea y se detallan antecedentes del ectoparasito en ésta y otras regiones. Conclusiones: la presencia de este parásito constituye evidencia de introducción de una especie exótica mediante la comercialización de sus hospedadores naturales y de la potencial colonización por patógenos introducidos en ambientes naturales, lo cual amenaza la integridad de estos ecosistemas.

Background: Lernaea cyprinacea was introduced in South America with cyprinids. To the best of our knowledge, this ectoparasite has not been reported in Santa Fe province (Argentina). Objective: To report Lernaea cyprinacea presence in Rhamdia quelen under hatchery conditions in Santa Fe province (Argentina). Methods: In May 2014, samples of L. cyprinacea attached to the fins and flanks of R. quelen were obtained in the Chronobiology Laboratory of the Veterinary Sciences School at Esperanza (Santa Fe, Argentina) where they were collected and identified. Results: A description of L. cyprinacea is presented along with detailed records previously reported in this and other regions. Conclusions: Presence of this parasite constitutes evidence of the introduction of exotic species through commercialization of their natural hosts and the potential pathogen colonization of natural environments, which constitutes a threat to the integrity of aquatic ecosystems., Resumo Antecedentes: Lernaea cyprinacea foi introduzido na América do Sul através de ciprinídeos, não sendo registrado na província de Santa Fe. Objetivo: relatar a sua presença no Rhamdia quelen, em condições de crescimento. Método: em maio de 2014, foram obtidas individuos de L. cyprinacea, parasitando nadadeiras e flancos em R. quelen, no Cronobiologia Laboratório da Faculdade de Ciências Veterinárias, Esperanza (Santa Fe, Argentina), que foram coletados e identificados. Resultados: uma descrição de L. cyprinacea é relatada, e detalhes prévios da presença deste parasito na região. Conclusões: a presença neste parasito é evidência de introdução de espécies exóticas através da comercialização de seus hospedeiros naturais. O potencial de colonização de patógenos introduzidos em ambientes naturais é uma ameaça à integridade dos ecossistemas., Resumen Antecedentes: la Lernaea cyprinacea fue introducida en América del Sur a través de los ciprínidos, no habiendo siendo previamente registrada en la provincia de Santa Fe (Argentina). Objetivo: reportar la presencia de Lernaea cyprinacea en Rhamdia quelen en condiciones de acuicultivo. Método: en mayo de 2014, se obtuvieron ejemplares de L. cyprinacea, parasitando aletas y flancos de R. quelen en el laboratorio de Cronobiología de la Facultad de Ciencias Veterinarias, en Esperanza (Santa Fe, Argentina), donde fueron colectados e identificados. Resultados: se brinda una descripción de L. cyprinacea y se detallan antecedentes del ectoparasito en ésta y otras regiones. Conclusiones: la presencia de este parásito constituye evidencia de introducción de una especie exótica mediante la comercialización de sus hospedadores naturales y de la potencial colonización por patógenos introducidos en ambientes naturales, lo cual amenaza la integridad de estos ecosistemas.