Control Of Fish Diseases Research Articles

Non-specific immune potentiating activity of fucoidan from a tropical brown algae (Phaeophyceae), Sargassum cristaefolium in tilapia (Oreochromis niloticus)

Fucoidan mainly produced by brown algae is a sulfated polysaccharide with fucose as a main molecule backbone. The objective of this research was to evaluate the non-specific immune potentiating activity of fucoidan from a tropical brown alga, Sargassum cristaefolium indigenous to the Gunungkidul coast, Yogyakarta, Indonesia. Fucoidan was extracted by acidic extraction, separated from alginate by CaCl2 precipitation and precipitated with ethanol. To know the component of fucoidan, acid hydrolysis was conducted and analyzed by using silica gel thin layer chromatography. In these analyses, a commercial fucoidan from Fucus vesiculosus was used as a standard fucoidan. Fucoidan isolated from S. cristaefolium was composed by monosaccharide components of fucose and galactose. The result revealed that injection of fucoidan increased phagocytic activity, total plasma protein, leukocrit and leukocyte count significantly (p < 0.05). The immunomodulating activity of fucoidan from S. cristaefolium was comparable to that of fucoidan standard from F. vesiculosus. However, administration of fucoidan did not affect the phagocytic index and leukocyte differentiation. Injection of fucoidan from S. cristaefolium effectively increased innate immunity parameters of tilapia at doses of 0.4–0.6 mg/kg fish suggested that this fucoidan was potential use for immunostimulant to control fish diseases.

Balık Beslemede Biyoteknolojik Uygulamalar

In order to put cultured species on the market with high quality and few casualties, many important studies are carried out. Most of the researches are conducted in the development of feed and feed ingredients 30-60% of the production cost in farming. Therefore, in aquaculture, an interest in alternative feed ingredients is moving at a very fast rate. In this context, the use of enzymes, probiotics and prebiotics in animal feed has steadily increased in recent years with reasons such as effective control of fish diseases and prevention of infection, strengthening the immune system of fish, increase of the digestibility, reduction of the feed cost, reduction of larval-term mortality, provision of increase in growth, live weight gain, and getting rid of the negative effects of stress.

魚類ウイルス病の防除に関する研究

魚類ウイルス病の防除に関する研究

AEROMONAS HYDROPHILA SENSITIVITY TO DISINFECTANTS

The aim of the present study was to determine the sensitivity of Aeromonas hydrophila to dis-infectants and to propose an efficient method for control of fish diseases caused by this patho-gen The tested A. hydrophila strains were inactivated by the combinations of glutaraldehyde, formaldehyde and quaternary ammonium salts (HMI® Glicofin) and glutaraldehyde, (ethylene-dioxy) dimethanol and benzalkonium chloride (Aldesept®). Iodine (Desinfekt B®), n-alkyl-dimethyl-benzyl-ammonium chloride (HMI® Roda Super), ethanol (40%, 50% and 70%) and potassium permanganate (1000 mg/l) were also found effective against A. hydrophila. At a concentration of 5 mg/L, potassium permanganate reduced A. hydrophila (?TCC 7965) counts by 3% (log10 0.25), while the strain was completely inactivated by 100 mg/L. Under the influ-ence of 5 mg/L and 100 mg/L potassium permanganate, the clinical A. hydrophila isolate counts were reduced by 0.7% (log10 0.06), and 2.3% (log10 0.19), respectively. Most tested disinfectants were effective against A. hydrophila, with the exception of potassium permanga-nate at 5 mg/L.

Edwardsiella tarda의 특이 Bacteriophage와 Bacillus subtilis KM-1혼합액이 Edwardsiella tarda 에 미치는 항균효과

본 연구는 E. tarda에 대한 특이박테리오phage와 생균제의 일종인 B. subtilis KM-1의 혼합제가 E. tarda에 대한 항균활성에 미치는 효과를 알아보고자 수행되었다. 가장 효과적인 혼합제의 항균활성을 보인 phage의 적정 수는 B. subtilis 가 <TEX>$2{\times}10^5$</TEX> CFU/ml의 농도로 존재할 때 배양 36시간째 <TEX>$2{\times}10^5$</TEX> PFU/ml로 나타났다. B. subtilis의 경우 <TEX>$2{\times}10^5$</TEX> PFU/ml의 phage가 존재할 때 첨가량에 비례하는 항균활성을 보여주었다. phage와 B. subtilis의 혼합투여는 phage나 B. subtilis 각각을 투여한 그룹보다 훨씬 높은 항균활성을 나타냈다. 본 연구의 결과는 수산양식에서 대두되고 있는 양식어류의 E. tarda 감염성 질병 치료를 위한 항생제 대체제로서의 사료첨가제 개발 가능성을 제시하고 있다. The present study was performed to investigate an antibacterial activity of specific bacteriophage (phage) and Bacillus subtilis KM-1 (B. subtilis) mixture against Edwardsiella tarda (E. tarda). An appropriate number of phage showing the most effective antibacterial activity was <TEX>$2{\times}10^5$</TEX> PFU/ml with <TEX>$1{\times}10^7$</TEX> CFU/ml of B. subtilis 36 h post incubation. On the other hand, B. subtilis showed a dose dependant manner in inducing antibacterial activity in the presence of phage (<TEX>$2{\times}10^5$</TEX> PFU/ml). The phage and B. subtilis mixture showed higher antibacterial activity against E. tarda than phage or B. subtilis only. These results suggest that the phage and B. subtilis mixture could be utilized as an alternative to antibiotics in the control of fish diseases caused by E. tarda.

Detection of the presence Aeromonas sp on nile tilapia cultured in floating net cage in lake Tondano

The purpose of this study was to detect the presence of bacteria Aeromonas sp in tilapia (Oreochromis niloticus). Nine fish with an average body weight of 150-200 g were used in this study as samples. Sampling was conducted at three different locations which were representative of fish culture sites located on Lake Tondano. The number of sample gathered from each location was and 3 fish which were taken randomly. Fish samples were taken by using a scoop, then the samples were taken alive by placing in an oxygen-filled plastic separately and taken direcly to lab Fish Disease Control and Environmental Center, Tateli, Department of Marine and Fisheries of North Sulawesi province, for examination the presence of bacteria. Isolation of bacteria were conducted by taking samples from gill and kidney. This study was carried out from April - July 2013. Identification of the presence of bacteria was done through a series of observations of colony morphology and gram staining of bacteria, followed by a series of biochemical tests: oxidase test , catalase test , test TSIA , H2S production test , indole test , motility test , citrate test, and test O/F. It could be concluded that 22.22 % of farmed nile tilapia in Lake Tondano were infected with the Aeromonas sp with the following percentage from each site: Paleloan village 7.40% , 7.40% Toulimembet village, and 7.40% Eris village. Keywords: Aeromonas sp, isolation, nile tilapia, floating net cage, Lake Tondano

Fish health status, research and management in East Africa: past and present

This paper reviews the state of research on fish pathogens in Burundi, Kenya, Rwanda, Tanzania and Uganda from the early 1900s, the period when fisheries management started in the region, to date, and evaluates the current policy, regulatory frameworks, management practices and frameworks for addressing fish health issues in East African Community countries. Host pathogens and their distributions are listed. To date, fish health research has focused on the occurrence and taxonomy of parasites mainly in wild hosts. Very limited research output and knowledge exist on bacterial, viral and fungal disease agents and on fish culture systems, as well as on parasites’ life cycles and/or vectors, epidemiology, pathogenicity, prevention and control. The current fish disease control and preventive strategies and diagnostic facilities are basic and non-specific. Although the five countries have legislation for the management of fisheries that clearly mention the restriction of movement of fish and fish products, they lack comprehensive policy and regulatory provisions to ensure an appreciable level of disease prevention and control. With the intensifying fish farming in the region, the research gaps in fish pathology, the potential impacts of the pathogens and the lack of appropriate management framework for fish diseases highlight the need to strengthen aquatic biosecurity.

海産魚介類の親魚養成と疾病防除に関する技術開発

海産魚介類の親魚養成と疾病防除に関する技術開発

An in vitro screening method to evaluate chemicals as potential chemotherapeutants to control Aeromonas hydrophila infection in channel catfish

To develop an in vitro screening method to be used for identifying potential effective chemotherapeutants to control Aeromonas hydrophila infections. Using catfish gill cells G1B and four chemicals (hydrogen peroxide, sodium chloride, potassium permanganate and D-mannose), the feasibility of using an in vitro screening method to identify potential effective chemotherapeutants was evaluated in this study. In vitro screening results revealed that, at concentration of 100 mg l⁻¹, H₂O₂ was the only chemical tested that was able to completely abolish the attachment and invasion of Aer. hydrophila to catfish gill cells. In vivo virulence studies using live channel catfish through bath immersion confirmed that H₂O₂ was the only chemical tested that was able to significantly (P < 0·001) reduce the mortality (from 90 or 100% to 0 or 20%) caused by Aer. hydrophila infections. The in vitro screening method using catfish gill cells G1B could be used to initially identify potential effective chemotherapeutants to control Aer. hydrophila. An in vitro screening method using catfish gill cells to identify potential effective chemotherapeutants described here will cut cost in research compared with the method of using live fish to screen lead compounds for fish disease control.

Immunological Control of Fish Diseases

All metazoans possess innate immune defence system whereas parameters of the adaptive immune system make their first appearance in the gnathostomata, the jawed vertebrates. Fish are therefore the first animal phyla to possess both an innate and adaptive immune system making them very interesting as regards developmental studies of the immune system. The massive increase in aquaculture in recent decades has also put greater emphasis on studies of the fish immune system and defence against diseases commonly associated with intensive fish rearing. Some of the main components of the innate and adaptive immune system of fish are described. The innate parameters are at the forefront of immune defence in fish and are a crucial factor in disease resistance. The adaptive response of fish is commonly delayed but is essential for lasting immunity and a key factor in successful vaccination. Some of the inherent and external factors that can manipulate the immune system of fish are discussed, the main fish diseases are listed and the pathogenicity and host defence discussed. The main prophylactic measures are covered, including vaccination, probiotics and immunostimulation. A key element in the immunological control of fish diseases is the great variation in disease susceptibility and immune defence of different fish species, a reflection of the extended time the present day teleosts have been separated in evolution. Future research will probably make use of molecular and proteomic tools both to study important elements in immune defence and prophylactic measures and to assist with breeding programmes for disease resistance.

KocuriaSM1 controls vibriosis in rainbow trout (Oncorhynchus mykiss, Walbaum)

To develop probiotics for the control of vibriosis caused by Vibrio anguillarum and Vibrio ordalii in finfish. Kocuria SM1, isolated from the digestive tract of rainbow trout, was administered orally to rainbow trout (Oncorhynchus mykiss) for 2 weeks at a dose equivalent to c. 10(8) cells per g of feed and then challenged intraperitoneally with V. anguillarum and V. ordalii. Use of SM1 led to a reduction in mortalities to 15-20% compared to 74-80% mortalities in the controls. SM1 stimulated both cellular and humoral immune responses in rainbow trout, by elevation of leucocytes (5.5 +/- 0.8 x 10(6) ml(-1) from 3.7 +/- 0.8 x 10(6) ml(-1)), erythrocytes (1.2 +/- 0.1 x 10(8) ml(-1) from 0.8 +/- 0.1 x 10(8) ml(-1)), protein (23 +/- 4.4 mg ml(-1) from 16 +/- 1.3 mg ml(-1)), globulin (15.7 +/- 0.2 mg ml(-1) from 9.9 +/- 0.1 mg ml(-1)) and albumin (7.3 +/- 0.2 mg ml(-1) from 6.1 +/- 0.1 mg ml(-1)) levels, upregulation of respiratory burst (0.05 +/- 0.01 from 0.02 +/- 0.01), complement (56 +/- 7.2 units ml(-1) from 40 +/- 8.0 units ml(-1)), lysozyme (920 +/- 128.8 units ml(-1) from 760 +/- 115.3 units ml(-1)) and bacterial killing activities. Kocuria SM1 successfully controlled vibriosis in rainbow trout, and the mode of action reflected stimulation of the host innate immune system. Probiotics can contribute a significant role in fish disease control strategies, and their use may replace some of the inhibitory chemicals currently used in fish farms.

Immunostimulants: The best alternative to vaccination and antibiotics in aquaculture

Immunostimulants comprise a group of biological and synthetic compounds that enhance the non-specific cellular and humoral defense mechanism in animals. These substances such as levamisole and glucan, peptidoglycon, chitin, chitosan, yeast and vitamin combinations as well as various products derived from plants and animals are effective in prevention of diseases. Use of expensive chemotherapeutants and antibiotics for controlling disease have widely been criticized for their negative impact like residual accumulation in the tissue, development of the drug resistance and immunosuppression, thus resulting in reduced consumer preference for food fish treated with antibiotics (Anderson,1992). Hence, instead of chemotherapeutic agents, increasing attention is being paid to the use of immunostimulants for disease control measures in aquaculture. The use of immunostimulants for the prevention of fish diseases is considered an attractive and promising approach. These immunostimulants mainly promote the function of phagocytes and increase their microbicidal power. They also enhance production of acute phase proteins that trigger the innate defence mechanism of the host. However, a controversy exists over the use of these substances, as in a few cases they have failed to render enhanced protection or increase in immunity. Long-term exposure, over and under dosing problems, timing and method of application of these substances are discussed here. This review article mainly considers the recent developments in this area to control fish diseases describing all different types and sources of immunostimulants, their characteristics, objective and evaluation of the mode of work.Key words: Immunostimulants, disease control, alternative, fish, antibiotics, aquaculture

Homogeneity among Lactococcus garvieae isolates from striped jack, Pseudocaranx dentex (Bloch &amp; Schneider), and its ectoparasites

Keywords: Benedenia sp., biased sinusoidal field gelelectrophoresis, Caligus longipedis, ectoparasites,Lactococcus garvieae, striped jack.Infectious diseases have become more serious inaquaculture with the rapid development of intensiveculture systems and the increase in fish and shellfishspecies cultured. Transmission of pathogenic micro-organisms to fish is mainly because of horizontalmechanisms. Among co-habiting fish, direct trans-mission of pathogens through the water is the mostimportant, especially when macroscopic and micro-scopic injuries occur on fish body surfaces, becom-ing potential portals of entry for bacterial pathogens(Kanno, Nakai & Muroga 1989; Amaro, Biosca,Fouz, Alcaide & Esteve 1995). Injuries on the skinand gills of fish are frequently caused by ectopar-asites, such as copepods and monogeneans, feedingon host mucus, tissue and blood (Cusack & Cone1986; Nylund, Bjorknes & Wallace 1991; Nylund,Wallace & Hovland 1993). By these feedingactivities, ectoparasites become effective mechanicalvectors, potentially transferring pathogens frominfected to non-infected fish (Ahne 1985; Cusack& Cone 1986; Donoghue 1986; Cusack, Rand C Nylund et al. 1991; Xu, Shoemaker K Bandilla, Valtonen, Suom-alainen, Aphalo & Hakalahti 2006; Pylkko, Soum-alainen, Tiirola & Valtonen 2006; Xu et al. 2007),but none of these studies showed a clear similaridentity between pathogens in both ectoparasitesand fish.The present study was designed to determine ifectoparasites carry the same pathogen as that ofdiseased fish. We targeted Lactococcus garvieae, oneof the major Gram-positive cocci pathogenic forfish as well as animals and humans (Wang, Shie,Chen, Huang, Hsieh, Wen, Lin & Wu 2007). InJapan, L. garvieae infection has caused severemortalities to cultured fish belonging to the familyCarangidae, such as the yellowtail, Seriola quinqu-eradiata Temminck & Schlegel, greater amberjack,Seriola dumerili (Risso), yellowtail amberjack, Seri-ola lalandi Valenciennes, and striped jack, Pseudo-caranx dentex Bloch & Schneider, since 1974 (Kitao1982; Kusuda, Kawai, Salati, Banner & Fryer 1991;Eldar, Ghittino, Asanta, Bozzeta, Goria, Prearo &Bercovier 1996). We used biased sinusoidal field gelelectrophoresis (BSFGE) to differentiate L. garvieaeisolates from different origins.During August 2006, two diseased striped jack of27–28 cm standard length were collected from afish farm and examined at the Fish Disease Control

Tri-Trophic Linkages in Disease: Pathogen Transmission to Rainbow Trout Through Stonefly Prey

Relationships between macroinvertebrates and microorganisms in aquatic environments are only poorly understood despite the fact that many aquatic macroinvertebrates feed on microbial biofilms during some life stage. Better understanding of trophic interactions between microbial biofilms, macroinvertebrates, and fish may also help control fish diseases and loss of natural resources. It has also been suggested that pollution, habitat fragmentation, and poor water quality may contribute to increased pathogenesis and mortality in fish. Increased disease incidence is difficult to assess, however, in part because of the complexity of pathogen transmission dynamics. Several environmental pathogens exist whose reservoir(s) and means of transmission remain poorly understood, highlighting the need to study pathogen ecology and interactions with organisms other than susceptible hosts. Aeromonas salmonicida is rarely isolated from freshwater sediments. However, stonefly nymphs were found to frequently harbor A. salmonicida and were shown to preferentially feed on the bacterium. Rainbow trout juveniles were presented with different feeding regimes to determine the transmission capacity of nymphs, and all fish fed stoneflies harboring A. salmonicida expressed symptoms of disease. Although current rates of furunculosis in freshwater ecosystems are unknown, trout primarily feed on stoneflies when water oxygen levels are high and temperatures are low (winter months), which is presumed to correspond to high resistance to the pathogen. Given that furunculosis is associated with physiological stress and higher water temperatures, its natural incidence may change in response to global or regional climatological effects.

Use of bacterial lipopolysaccharide (LPS) as an immunostimulant for the control ofAeromonas hydrophilainfections in rainbow troutOncorhynchus mykiss(Walbaum)

To determine the effect of lipopolysaccharide (LPS) for the prevention of infection by Aeromonas hydrophila in rainbow trout (Oncorhynchus mykiss Walbaum) fingerlings. Rainbow trout fingerlings were fed with 0 mg (= controls), 1.875 mg, 3.75 mg, 7.5 mg and 15 mg of LPS per 100 g of commercial feed for 14 days before experimental challenge with A. hydrophila. The results revealed a reduction in mortalities to 5% in the two lowest doses and 15% in the group, which received 15 mg LPS per 100 g of feed, compared with 45% mortalities in the control. LPS exerted a powerful oxidative burst effect and was a potent mediator of phagocytic, lysozyme, bactericidal and antiprotease activities and total protein. However, whereas there were increases in specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) in LPS-treated fish, the data were not significantly (P > 0.05) different. LPS was effective at preventing disease caused by A. hydrophila and in stimulating the innate immune response of rainbow trout. The results of this study highlight the role of LPS in fish disease control.

The use of immunostimulating herbs in fish. An overview of research

The use of immunostimulants as an alternative to the drugs, chemicals and antibiotics currently being used to control fish diseases in fish culture is attracting the attention of many researchers. In this context, many have focused on the use of medicinal plant products as potential therapeutic measures for modulating the immune response and, specifically, on the use of herbs to prevent and control fish diseases. Medicinal plants (plant remedies) are a deeply rooted component of the cultural heritage of many people from diverse cultures and countries and are, as such, closely linked to the maintenance of good health. The aim of this paper is to review research currently being carried out on the herbs and herbal extracts that have been shown to modulate the immune system of fish. Special attention is given to the use of Chinese and Indian herbs.

Potential of Psidium guajava Supplemented Fish Diets in Controlling Aeromonas hydrophila Infection in Tilapia (Oreochromis niloticus)

Fourteen herbs were extracted in water, 95% ethanol, and ether, and tested in vitro for antimicrobial activities against Aeromonas hydrophila, a fish pathogen causing motile Aeromonas septicemia. Using swab paper disc assays and minimal inhibitory concentration (MIC) determinations, we noted that the ethanol extract of Psidium guajava leaf exhibited the strongest antimicrobial activity. The extract allowed growth-inhibited A. hydrophila cells to regrow in fresh BHI broth indicating a bacteriostatic mode of action. In a pathogenicity test, the median lethal dose (LD(50)) of A. hydrophila for tilapia (Oreochromis niloticus) by intraperitoneal injection was 3.44 x 10(6) CFU/ml. In vivo experiments showed that fish diets containing either dry leaf powder of P. guajava or dried ethanol extract of P. guajava leaf reduced mortality of A. hydrophila infected tilapia with no detected adverse effect on the fish. This study suggests that P. guajava leaf has the potential to control fish diseases caused by A. hydrophila.

Sensibilidade antimicrobiana de bactérias isoladas de Jundiá (Rhamdia quelen)

Objetivando o delineamento do perfil de sensibilidade dos agentes bacterianos causadores de enfermidades em peixes, 51 isolados bacterianos provenientes de Jundiá e pertencentes aos gêneros Acinetobacter spp. (8), Aeromonas spp. (15), Edwardsiella spp. (2), Enterobacter spp. (2), Klebsiella spp. (1), Plesiomonas spp. (5), Pseudomonas spp. (1), Staphylococcus spp.(11) e Vibrio spp. (6) foram testados frente aos antimicrobianos utilizados no tratamento de enfermidades em peixes. Dos 51 isolados bacterianos obtidos de exemplares de Jundiá (Rhamdia quelen) 51 (100%) foram sensíveis a gentamicina, 49 (96,08%) ao sulfazotrim, 47 (92,16%) ao cloranfenicol, 43 (84,31%), a tetraciclina, 43 (84,31%) ao ácido nalidíxico, 31 (60,78%) à nitrofurantoina, 22 (43,14%) à eritromicina, 22 (43,14%) à ampicilina, 15 (29,41%) à espiramicina, 13 (25,50%) à colistina e 5 (3%) foram sensíveis a penicilina G. Com exceção de um isolado do gênero Staphylococcus spp., as bactérias analisadas no presente estudo foram resistentes a um ou mais agentes antimicrobianos testados. O conhecimento do perfil de sensibilidade das bactérias envolvidas em processos infecciosos nos peixes permitirá aos técnicos à adoção de uma antimicrobianoterapia racional, que contribuirá para o controle das enfermidades em Rhamdia quelen, sem causar grandes riscos à saúde pública e ao meio ambiente.

Detection and Identification of Fish Pathogens: What is the Future?

Fish diseases pose a universal threat to the ornamental fish industry, aquaculture, and public health. They can be caused by many organisms, including bacteria, fungi, viruses, and protozoa. The lack of rapid, accurate, and reliable means of detecting and identifying fish pathogens is one of the main limitations in fish pathogen diagnosis and disease management and has triggered the search for alternative diagnostic techniques. In this regard, the advent of molecular biology, especially polymerase chain reaction (PCR), provides alternative means for detecting and iden- tifying fish pathogens. Many techniques have been developed, each requiring its own protocol, equipment, and expertise. A major challenge at the moment is the development of multiplex assays that allow accurate detection, identification, and quantification of multiple pathogens in a single assay, even if they belong to different superkingdoms. In this review, recent advances in molecular fish pathogen diagnosis are discussed with an emphasis on nucleic acid-based detec- tion and identification techniques. Major features and applications of current predominant meth- ods and promising methods likely to impact future fish disease control and prevention are out- lined.

Genetic analysis of infectious pancreatic necrosis virus from Scotland

Infectious pancreatic necrosis (IPN) is a highly contagious disease of young salmonid fish, and is one of the most serious economic diseases in aquaculture. In Scotland, an increase in IPN virus (IPNV) outbreaks in seawater Atlantic salmon, Salmo salar, has been reported in recent years. The aim of this study was to analyse the VP2 gene from recent IPNV isolates from Scotland, to determine whether there are epidemiological links between IPNV isolates from farms (13), wild fish (17) and the environment (6) in order to investigate potential wild and farmed fish interactions. Comparison of the nucleotide sequence of the VP2 gene revealed that 34 of 36 isolates were 97.1-100% similar and the deduced amino acid sequences showed 97-100% identity. Two isolates from wild fish exhibited the most divergence at 85-87.3% similarity to the other isolates at the nucleotide level and 88.2-90.8% identity at the deduced amino acid level. Phylogenetic analyses revealed that 34 of 36 of the isolates from Scotland were genetically closely related to the A2 (Sp) serotype of IPNV. The two wild isolates from seatrout, Salmo trutta, and flounder, Platichthys flesus, were most closely related to the European A5 (Te) serotype. This study represents a comprehensive IPNV phylogenetic study that indicates that there are closely related or identical isolates in circulation in the marine environment, which adds evidence that disease interactions between wild and farmed fish may occur. This type of analysis is a useful tool in the management and control of fish diseases because it can assist in the identification of epidemiological links and highlight potential risks to aquaculture.