Epizootic Ulcerative Syndrome Research Articles

Epidemiology and Economics Support Decisions about Freedom from Aquatic Animal Disease.

In this study, we review the application of epidemiology and economics to decision-making about freedom from aquatic animal disease, at national and regional level, and recent examples from Europe. Epidemiological data (e.g. pathogen prevalence and distribution) determine the technical feasibility and cost of eradication. The eradication of pathogens which exist in wild populations, or in a latent state, is technically difficult, uncertain and expensive. Notably, the eradication of diseases of molluscs is rarely attempted because host populations (farmed and wild) cannot be completely removed from open water systems. Doubt about the success of eradication translates into uncertain ex-ante cost estimates. Additionally, the benefits of an official disease-free status cannot be estimated with any accuracy. For example, in Europe, official freedom from epizootic ulcerative syndrome and white spot syndrome virus has not been pursued, arguably because the evidence does not exist for the benefits (reduced risk of disease in wild populations) to be estimated and thus weighed against the costs of maintaining disease freedom (e.g. restriction on imports). Economic analysis must assess not only whether the benefits of disease freedom outweigh costs, but whether it is the economically optimal disease control option. Government may also want to compare investment in aquatic animal health with other opportunities. As resources become scarce, governments have sought to share costs of disease control with industry, and thus to ensure equity, the distribution benefits must be known so costs can be borne by those who benefit. The economic principles to support decisions about disease freedom are well established, but their application is constrained by lack of epidemiological data, which may explain the lack of economic analysis in support of aquatic animal management in Europe. The integration of epidemiology and economics in disease control planning will identify research aimed at improving the underpinning evidence base.

Investigation on culture and health status of Mrigal Cirrhinus cirrhosus from the farming system of Mymensingh region

Indian major carp, Cirrhinus cirrhosus was considered to monitor culture and health status in farm condition from Bhaluka and Muktagacha of Mymensingh region of Bangladesh for a period of seven months starting from September, 2010 to March, 2011. Monthly sampling was carried out for growth and health condition. Samples of skin and muscle, gill, liver and kidney were observed by clinical and histological techniques. Water temperature was at unfavorable levels but, dissolved oxygen, pH, alkalinity, ammonia and nitrite of water were within the favorable range for fish culture during the months of December and January. Clinically weak body, rough skin, scale loss, thick gill filaments, ulcer and gray brownish color were observed. Among the affected fish organs like skin, muscle and gill were found to be more affected than those of the internal organs, liver and kidney. Major pathologies in the skin and muscle were loss of epidermis and dermis, presence of fungal granuloma, fungal hyphae, necrosis, hemorrhages, vacuums and melanocytes. Protozoan cysts, clubbing, hemorrhages, necrosis and hypertrophy were found in the gill. Necrosis, hemorrhage, pyknosis and vacuums were observed in liver. Common pathological signs like necrosis, hemorrhage, pyknosis, vacuums and degenerated kidney tubules were noticed in kidney. Overall, in the clinical and histopathological studies fishes were found to be more affected during the colder months i.e., December and January. Whereas, in the month of February the pathological condition of fish gradually started to heal up. In histopathological observation, fishes of Bhaluka farms were more affected than that of Muktagacha fish farms. Epizootic ulcerative syndrome (EUS) and protozoan diseases were noticed in Bhaluka fish farms. DOI: http://dx.doi.org/10.3329/jbau.v11i2.19947 J. Bangladesh Agril. Univ. 11(2): 391-397, 2013

Investigation on fish health and diseases in rural pond aquaculture in three districts of Bangladesh

The present study was conducted to know the culture strategies and fish health and disease problems in pond aquaculture in Mymensingh, Bogra and Pabna districts of Bangladesh. Questionnaire interview and participatory rural appraisal tools like focus group discussion (FGD) were conducted with selected fish farmers. In total 90 farmers were interviewed and 9 FGD sessions were conducted. Most of the respondents practiced carp and pangas polyculture and they had disease problems in their ponds. Prevalence of fish disease varied with cultured species and locations. The most prevalent diseases as reported by the farmers were pop eye (57.78%), ventral reddening (55.55%), tail and fin rot (48.89), hemorrhagic lesion over the body surface (45.56%), dropsy (40%), gill rot (40%), white spot (40%) and epizootic ulcerative syndrome or EUS (33.33%). According to farmers opinion most susceptible species to disease was silver carp, Hypophthalmichthys molitrix (57.78%); followed by mrigal, Cirrhinus cirrhosus (50%); catla, Catla catla (47.78%); sarputi, Barbodes gonionotus (47.78%); rui, Labio rohita (42.22%) and pangas, Pangasianodon hypophthalmus (42.22%). Higher mortality was found in pangas (53.56%). Clinically, pangas, koi and sarputi were found severely affected. Most of the farmers used some treatment measures against disease problems. This study also highlited some fish health management problems in pond aquaculture. Further studies should include identification and characterization of pathogens involved in different types of diseases in pond aquaculture. DOI: http://dx.doi.org/10.3329/jbau.v11i2.19944 J. Bangladesh Agril. Univ. 11(2): 377-384, 2013

Emergence of Epizootic Ulcerative Syndrome: Large-Scale Mortalities of Cultured and Wild Fish Species in Uttar Pradesh, India

Epizootic ulcerative syndrome (EUS), a disease listed by World Organisation for Animal Health (OIE) has been reported in 26 countries across 4 continents. Till date, 94 fish species have been found to be naturally infected with EUS and its host range is gradually expanding. In the year 2010-11, outbreaks resulting in heavy fish mortality were recorded in wetland districts of Uttar Pradesh, India, and EUS was confirmed as the cause of mortality on the basis of histopathology, isolation of Aphanomyces invadans , bioassay and PCR. A prevalence of ∼69% (371/540) was recorded and 13 fish species were found to be infected. Interestingly, EUS was observed in seven new species ( Aristichthys nobilis, Channa punctatus, Wallago attu, Mastacembelus armatus, Mystus cavasius, Anabas testudineus and Puntius conchonius ) for the first time in natural outbreaks. Furthermore, the disease was observed even in the month of May when the mean water temperature was 31.6±0.65°C. This suggests that the disease can result in severe losses even after two decades of its emergence.

Innate immune response of Indian major carp, Labeo rohita infected with oomycete pathogen Aphanomyces invadans

The fish pathogenic oomycete Aphanomyces invadans is the causative agent of epizootic ulcerative syndrome (EUS), a fish disease of international significance and reportable to the World Organisation for Animal Health. In spite of the current and potential impact of A. invadans infection on fisheries and aquaculture sectors of the world, very little is known about the host-A. invadans interactions. In the present study, following experimental infection with A. invadans in one of the Indian major carps, Labeo rohita, sequential changes in various innate immune parameters were monitored. The results indicated that at early stages of infection, no significant changes in any of the studied innate immune parameters were observed. However, at the advanced stages of infection from 6 to 12 days post infection (dpi), the respiratory burst and alternate complement activity were significantly higher whereas lysozyme, antiproteases and α-2 macroglobulin values were significantly lower than the control group and also from the infected group at earlier stages of infection. Since, the possibility of vaccination of fish against A. invadans appears remote due to difficulties in eliciting a specific antibody response, the information generated in the present study could be useful for developing strategies for improving resistance to A. invadans infection by stimulating the innate immunity through immunomodulation.

A murrel interferon regulatory factor-1: molecular characterization, gene expression and cell protection activity.

In this study, we have reported a first murrel interferon regulatory factor-1 (designated as Murrel IRF-1) which is identified from a constructed cDNA library of striped murrel Channa striatus. The identified sequence was obtained by internal sequencing method from the library. The Murrel IRF-1 varies in size of the polypeptide from the earlier reported fish IRF-1. It contains a DNA binding domain along with a tryptophan pentad repeats, a nuclear localization signal and a transactivation domain. The homologous analysis showed that the Murrel IRF-1 had a significant sequence similarity with other known fish IRF-1 groups. The phylogenetic analysis exhibited that the Murrel IRF-1 clustered together with IRF-1 members, but the other members including IRF-2, 3, 4, 5, 6, 7, 8, 9 and 10 were clustered individually. The secondary structure of Murrel IRF-1 contains 27% α-helices (85 aa residues), 5.7% β-sheets (19 aa residues) and 67.19% random coils (210 aa residues). Furthermore, we predicted a tertiary structure of Murrel IRF-1 using I-Tasser program and analyzed the structure on PyMol surface view. The RNA structure of the Murrel IRF-1 along with its minimum free energy (-284.43 kcal/mol) was also predicted. The highest gene expression was observed in spleen and its expression was inducted with pathogenic microbes which cause epizootic ulcerative syndrome in murrels such as fungus, Aphanomyces invadans and bacteria, Aeromonas hydrophila, and poly I:C, a viral RNA analog. The results of cell protection assay suggested that the Murrel IRF-1 regulates the early defense response in C. striatus. Moreover, it showed Murrel IRF-1 as a potential candidate which can be developed as a therapeutic agent to control microbial infections in striped murrel. Overall, these results indicate the immune importance of IRF-1, however, the interferon signaling mechanism in murrels upon infection is yet to be studied at proteomic level.

Impact of diseases on fish production of baors in Jessore, Bangladesh

The study was carried out to assess the impact of diseases on fish production in baors of Jessore district, Bangladesh from March 2012 to January 2013. Studied baors were selected randomly from each sub-district which covered 39.22% of total baors and 71.87% baor areas in Jessore district. All the surveyed baors were affected more or less by various diseases and in 80% baors noticeable production loss occurred almost every year. The main diseases were epizootic ulcerative syndrome (EUS), dropsy, gill rot and fin rot; out breaking time ranged from November to February each year. EUS was recorded in 85% baors whereas other diseases were found in various baors at various percentages: dropsy (75%), gill rot (45%) and fin rot (55%). Conferring to the number of affected fishes, 31.25% were affected by EUS, 37.5% by dropsy, 12.5% by gill rot and 18.75% by fin rot. In the year 2012, 0.513% loss of production has occurred that designated 0.7599 million BDT. Through successful work on disease control and management, production loss may be minimized.

Impact of diseases on fish production of baors in Jessore, Bangladesh

The study was carried out to assess the impact of diseases on fish production in baors of Jessore district, Bangladesh from March 2012 to January 2013. Studied baors were selected randomly from each sub-district which covered 39.22% of total baors and 71.87% baor areas in Jessore district. All the surveyed baors were affected more or less by various diseases and in 80% baors noticeable production loss occurred almost every year. The main diseases were epizootic ulcerative syndrome (EUS), dropsy, gill rot and fin rot; out breaking time ranged from November to February each year. EUS was recorded in 85% baors whereas other diseases were found in various baors at various percentages: dropsy (75%), gill rot (45%) and fin rot (55%). Conferring to the number of affected fishes, 31.25% were affected by EUS, 37.5% by dropsy, 12.5% by gill rot and 18.75% by fin rot. In the year 2012, 0.513% loss of production has occurred that designated 0.7599 million BDT. Through successful work on disease control and management, production loss may be minimized.

Biosecurity risks associated with epizootic ulcerative syndrome and iridovirus in ornamental fish imported into the European Union

Aphanomyces invadans is the main causative agent of epizootic ulcerative syndrome (EUS), a seasonal epizootic condition, which is associated with morbidity and mortality in farmed and wild fish worldwide (Roberts...

Epizootic ulcerative syndrome (EUS) in fish: history and current status of understanding

Epizootic ulcerative syndrome (EUS) is one of the most important diseases affecting more than 100 species of wild and cultured finfish. EUS was first reported in farmed ayu (Plecoglossus altivelis) from Japan in 1971 and has since then spread across different countries of four continents including Asia, Australia, North America and Africa. The spread of the disease, especially in Asia–Pacific region and Africa has led to substantial damage to the fish resources and livelihood of the fish farmers. No reports are available confirming the outbreak of the disease from Europe and South America. The latest outbreak of EUS has been reported from Canada in a new susceptible species brown bullhead, Ameiurus nebulosus. It seems that the disease has potential to spread further, owing to the epizootic nature of the disease and broad susceptible host range. Considering the global importance of this disease, this review provides the current status of understanding about the etiology, process of diseases development, species affected, diagnostic methods as well as control and preventive measures, in light of the historical developments in those areas.

Aeromonas veronii infection in the cultured snakehead fish, Ophiocephalus argus (Cantor)

Aeromonas veronii has been identified as a causative agent of fish and human disease outbreaks. However, there is no definitive data on A. veronii infection in cultured snakehead fish Ophiocephalus argus (Cantor). In this study, a virulent strain S-L was isolated from the farmed snakehead fish suffering from epizootic ulcerative syndrome, and identified as an A. veronii strain using ARIS 2X system. Its taxonomic position was further determined through nucleotide blast search in NCBI website and phylogenetic analysis. The constructed phylogenetic tree using neighbor-joining method further showed that the S-L isolate was the A. veronii strain (GenBank accession no. JQ301790), which was also previously isolated from diseased freshwater fish. In addition, five genes encoding aerolysin, haemolysin, serine protease and two cytotonic enterotoxins were all found present in the S-L isolate which further confirmed its potential virulence. As far as we know, this is the first report of farmed snakehead fish infected with A. veronii. Key words: Ophiocephalus argus (Cantor), Aeromonas veronii, epizootic ulcerative syndrome, identification.

Gold-nanoparticle based electrochemical DNA sensor for the detection of fish pathogen Aphanomyces invadans

Epizootic ulcerative syndrome (EUS) is a devastating fish disease caused by the fungus, Aphanomyces invadans. Rapid diagnosis of EUS is needed to control and treat this highly invasive disease. The current diagnostic methods for EUS are labor intensive. We have developed a highly sensitive and specific electrochemical genosensor towards the 18S rRNA and internal transcribed spacer regions of A. invadans. Multiple layers of latex were synthesized with the help of polyelectrolytes, and labeled with gold nanoparticles to enhance sensitivity. The gold-latex spheres were functionalized with specific DNA probes. We describe here the novel application of this improved platform for detection of PCR product from real sample of A. invadans using a premix sandwich hybridization assay. The premix assay was easier, more specific and gave higher sensitivity of one log unit when compared to the conventional method of step-by-step hybridization. The limit of detection was 0.5 fM (4.99 zmol) of linear target DNA and 1 fM (10 amol) of PCR product. The binding positions of the probes to the PCR amplicons were optimized for efficient hybridization. Probes that hybridized close to the 5' or 3' terminus of the PCR amplicons gave the highest signal due to minimal steric hindrance for hybridization. The genosensor is highly suitable as a surveillance and diagnostic tool for EUS in the aquaculture industry.

Immune response and status of epizootic ulcerative syndrome (EUS) affected fishes Channa punctatus and Clarias magur

In Epizootic ulcerative syndrome (EUS) affected Channa punctatus and Clarias magur, the serum total proteins were decreased by 24.63% and 38.75% respectively along with A:G ratio. During immune response, the antibodies produced were found to be positively exponential with the amount of antigens (bacteria, fungus and viruses). The present changes may be because of the changing environmental conditions especially temperature fluctuations producing stress conditions in the fishes.

Use of low-cost chemotherapeutic and medicinal plants against Thai silver barb (Barbonymus gonionotus)

Studies were conducted to select and apply the effective low-cost chemotherapeutic and medicinal plants against diseased fish under laboratory and field condition. Thai silver barbs (Barbonymus gonionotus) weighing 20-25 gm were experimentally infected with a virulent bacterial pathogen (Aeromonas hydrophila) and a fungal pathogen (Aphanomyces invadans). Based on the previous studies, four chemotherapeutics, viz., salt + lime, alum, doxycycline and oxytetracycline were selected and applied to observe the therapeutic effects under laboratory and field condition. In the case of medicinal plants, leaves/ bulb / seeds/ rhizome of neem (Azadirachta indica), akand (Calotropis gigantea), garlic (Allium sativum), turmeric (Curcuma longa), shoti (Curcuma zedoaria), Indian sorrel (Oxalis corniculata), guava (Psidum guajava) and kalijira (Nigella sativa) were screened out and applied to the infected fish in laboratory and field condition to determine their efficacies. The antibiotics, both oxytetracycline and doxycycline were found to be very efficient followed by salt + lime and alum. For fungal infection, alum was excellent followed by salt + lime both under laboratory and field condition. Even in the pond trial, alum and salt + lime successfully checked the occurrence of epizootic ulcerative syndrome (EUS) and similar diseases. In the case of medicinal plants, neem and akand together reduced the occurrence bacterial and fungal disease. Garlic was very efficient to check bacterial infection but weak against fungal disease. Turmeric and arrowroot were found to be highly effective against fungal disease but moderately effective against bacterial disease. Field trial revealed that Indian sorrel and guava were highly efficient against bacterial disease but poorly efficient against fungal disease. On the other hand, arrowroot and black cumin were highly efficient against fungal disease but moderately efficient against bacterial disease. The results would be useful to the all concerned for proper health management of cultured fishes.DOI: http://dx.doi.org/10.3329/jbau.v10i2.14932 J. Bangladesh Agril. Univ. 10(2): 385-390, 2012

Environmental Impact Assessment of Fish Diseases on Fish Production

The present research work was conducted from July 2008 to June 2009 to investigate intensity of infestation of parasites in freshwater fishes and the impact of fish diseases on fish production in northern region of Bangladesh. Possibility of out break of diseases due to deterioration of environmental factors of water bodies was included in this study. The diseases identified were ulcer diseases, EUS (Epizootic Ulcerative Syndrome), Ichthyophthiriasis, Trichodiniasis, Chilodoneliasis, Myxoboliasis, Dactylogyrosis, Gyrodactylosis, Argulosis, Pernicious anaemia, Red spot disease, Red Pest of freshwater eel, Mouth fungus, Branchiomysis, Abdominal dropsy and whirling disease. The infestation more occurred in young fishes than in adult fishes. The overall water qualities of water bodies fluctuated from July 2008 to June 2009. Physicochemical parameters have more or less significant combined effect on the deterioration of water quality as well as fish diseases. Gills were the most affected sites and parasites damaged gill filaments by rupturing blood capillaries, causing necrosis, coagulation and hemorrhage. The present study revealed the prevalence of different organisms in fishes, which are potential pathogen for them. Fishes were infested by parasites and other pathogens. From overall study it was observed that the parasites, bacteria and fungus were most important pathogen for outbreak of diseases. It was also observed that there was a direct relation between disease outbreak among fishes and environmental factors. Low alkalinity reduces the buffer capacity of water and badly affects the pond ecosystem, which in turn cause stress to the fish and become more susceptible to diseases. In case of low aquatic environmental temperature fish reduces metabolic activities, which in turn makes the fish more susceptible during the winter period towards parasitic infection. DOI: http://dx.doi.org/10.3329/jsf.v9i1-2.14655 J. Sci. Foundation, 9(1&2): 125-131, June-December 2011

Use of Aqua-chemicals in the Hatcheries and Fish Farms of Greater Noakhali, Bangladesh

This study was carried out in greater Noakhali region (Lakshmipur, Noakhali and Feni) to evaluate the type of aqua-chemicals used in aquaculture activities where data were collected through questionnaire interview, Focus Group Discussion (FCD), personal contact with fish farmers, hatchery and nursery owner, farm workers. A variety of aqua drugs and chemicals including antibiotics have been using in the region by farmers for fish health management and increasing production. Aqua-chemicals were commonly used for pond preparation, disease control and treatment of the carps, tilapia, prawns and weed fishes. Carps show very positive results when they were treated against the diseases, Motile Aeromonas Septicaemia (MAS), Epizootic Ulcerative Syndrome (EUS), Saprolegniasis, Argulosis, Fin rot, Dropsy, Ichthyophthiriasis with oxytetracycline, potassium permanganate, sumithione, malachite green, dipterex, pillar sulfan, secofon, timsen, geolite and lime. The study also identified the problems associated with the use of chemicals which included lack of knowledge regarding the use of chemicals, appropriate dose, method of application and indiscriminate use of chemicals.

General properties of water of Baidya fish pond, Tankisinwari, Nepal

In the present study, ranges and correlation among different physicochemical parameters viz., air temperature, water temperature, pH, turbidity, total dissolved solids, conductivity, dissolved carbon dioxide, ammonia, nitrate, dissolved oxygen, biological oxygen demand, chloride, total alkalinity, total hardness and phosphate were taken into consideration. The water quality of Baidya fish pond was normal except high fluctuation of chloride 1±0.241 to 29.84±0.260 mg/l and ammonia 1.55±0.088 to 18.7±0.061 mg/l during manuaring period and casual addition of wastes like toilet cleaners, caustic potash etc. Outbreak of epizootic ulcerative syndrome (EUS) was observed at the periphery of Baidya fish farm during winter months when polluted cold water from Koshi canal was added. The affected fishes developed several lesions around the body and fin rot. Due to sudden fall in dissolve oxygen, less than 4 mg/l during April and May, 2010 mass mortality of fishes Labeo rohita, Cirrhina mrigala, Hypothalamichthys molitrix, Aristichthys nobilis occurred. When chicken droppings were added in pond, ammonia was raised up to 18.7 mg/l which led to mass mortality of fish (Pangasius) during August. DOI: http://dx.doi.org/10.3126/njbs.v2i0.7490 Nepalese Journal of Biosciences 2 : 55-63 (2012)

Effect of probiotic on haematogical paramaters of diseased fish (Cirrihinus mrigal)

Epizootic ulcerative syndrome (EUS) is a dreadful disease of several aquatic animals including mrigal (Cirrhinus mrigala Ham.). Prevention of the disease with the help of chemical compo-unds may prove harmful for the fish as well as the end consumer. Now-a-days the use of pro-biotics has become firmly established due to their beneficial effects at the nutritional as well as therapeutic levels. Therefore, research efforts have been concentrated on optimizing production with eco-friendly alternatives to the therapeutic use of antimicrobials. Commercially available probiotics were used for controlling this disease in mrigal in the present study. The effect of probiotic on four haemotogical parameters viz. amount of haemoglobin (Hb), hemocrit / pac-ked cell volume (PCV), total erythrocyte count (TEC), and total leucocytes count (TLC) were studied over a period of eight weeks. The level of these parameters decreased significantly in the blood of fish treated with pathogenic bacteria. The fish administrated with probiotics showed significant increase in the hematological parameters thus contributing towards overall health of the fish.

Development and standardization of a monoclonal antibody-based rapid flow-through immunoassay for the detection ofAphanomyces invadansin the field

A monoclonal antibody-based flow-through immunoassay (FTA) was developed using a nitrocellulose membrane placed on the top of adsorbent pads enclosed in a plastic cassette with a test zone at the center. The FTA could be completed within 10 min. Clear purple dots against a white background indicated the presence of Aphanomyces (A.) invadans. The FTA limit of detection was 7 µg/mL for A. invadans compared to 56 µg/mL for the immunodot. FTA and polymerase chain reaction (PCR) could detect A. invadans in fish tissue homogenates at a 10-11 dilution compared to a 10-8 dilution by immunodot. In fish suffering from natural cases of epizootic ulcerative syndrome (EUS) collected from Mangalore, India, FTA and PCR could detect A. invadans in 100% of the samples compared to 89.04% detected by immunodot. FTA reagents were stable and produced expected results for 4 months when stored at 4~8℃. This rapid test could serve as simple and cost-effective on-site screening tool to detect A. invadans in fish from EUS outbreak areas and in ports during the shipment of live or frozen fish.

Detection of Aphanomyces invadans and epizootic ulcerative syndrome in the Murray‐Darling drainage

Epizootic ulcerative syndrome was diagnosed, and the presence of Aphanomyces invadans confirmed, from an outbreak of clinical disease in wild-caught bony bream (Nematalosa erebi) from the Darling River near Bourke, in New South Wales, Australia, during 2008. This confirms a significant extension of the agent beyond its historical range.