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At least 19 recordsLinked to original sources

PubMed2004

Gross pathology and its relationship with histopathology of amoebic gill disease (AGD) in farmed Atlantic salmon, Salmo salar L.

Gross pathological assessment of amoebic gill disease (AGD) is the only non-destructive, financially viable method for rapid and broad-scale disease management of farmed Atlantic salmon, Salmo salar L., in Tasmania. However, given the presumptive nature of this diagnosis, the technique has been considered questionable. This study investigated the degree of conformity between clinical signs and histological lesions observed in a commercial setting. Three groups of Atlantic salmon (n = 42, 100 and 100, respectively) were collected from various farm sites in southern Tasmania between December 2001 and April 2003. Micro-stereoscopic analysis showed that grossly affected tissue regions correspond to areas of hyperplastic lamellar fusion, generally in association with attached Neoparamoeba sp. Agreement between gross signs of AGD and histopathological diagnosis was compared. Kappa analysis indicated moderate to good agreement between methods (kappa = 0.52-0.74). Individual cases of disagreement were further scrutinized and several factors were found to influence the level of agreement between the two methods. Stage of disease development, lesions derived from other pathogens, assessor interpretation/experience, sampling methods, histological technique and/or experience were potential confounding factors. It was concluded that clinical diagnosis is acceptable as a farm-monitoring tool only. Removal of grossly affected tissue and subsequent histological examination is recommended to improve diagnostic accuracy.

Amebiasis↗

PubMed2003

In vitro evaluation of the susceptibility of Edwardsiella ictaluri, etiological agent of enteric septicemia in channel catfish, Ictalurus punctatus (Rafinesque), to florfenicol.

In vitro studies were conducted to assess the sensitivity of Edwardsiella ictaluri, the etiological agent of enteric septicemia of catfish (ESC), to the antibacterial drug florfenicol (FFC). Twelve different E. ictaluri isolates from cases submitted between 1994 and 1997 to the Thad Cochran National Warmwater Aquaculture Center fish diagnostic laboratory (Stoneville, MS) were used for testing. These isolates originated from channel catfish (Ictalurus punctatus) infected with E. ictaluri through natural outbreaks of ESC in the commercial catfish ponds in Mississippi. Seven hundred sixty-seven additional cultures of E. ictaluri were obtained from channel catfish infected experimentally with E. ictaluri. In some of these experimental infections, FFC was used for treatment. These cultures of E. ictaluri were identified by morphological and biochemical tests. Kirby-Bauer zones of inhibition (in mm) for FFC against E. ictaluri were determined using standard methods. The minimum inhibitory concentration (MIC) of FFC was determined for the natural outbreak E. ictaluri isolates and arbitrarily selected experimental cultures. The zones of inhibition for FFC tested with E. ictaluri ranged from 31 to 51 mm. The MIC for FFC tested with E. ictaluri was consistently 0.25 microg/ml. Edwardsiella ictaluri tested in these studies were highly sensitive to FFC in vitro.

Animals↗

PubMed2005

Viruses of pet fish.

Investigation of a fish kill should begin with water quality analysis and use of standard necropsy techniques to rule out the role of parasites or bacteria. The presence of a virus does not mean necessarily that it is a pathogen. Another point to consider is the potential influence of water temperature on pathogenicity; this may be an important factor in developing disease. A list of laboratories that is approved by the USDA to conduct diagnostic testing of aquaculture species can be found at: http://www.aphis.usda.gov/vs/nvsl/labcertification/aquaapplab.htm.

Animals↗

PubMed2006

Application of molecular diagnostic methods to penaeid shrimp diseases: advances of the past 10 years for control of viral diseases in farmed shrimp.

The most important diseases of farmed penaeid shrimp have infectious aetiologies. Among these are diseases with viral, rickettsial, bacterial, fungal and parasitic aetiologies. Diagnostic methods for these pathogens include the traditional methods of gross pathology, histopathology, classical microbiology, animal bioassay, antibody-based methods, and molecular methods using DNA probes and DNA amplification. While methods using clinical chemistry and tissue culture are standard methods in veterinary and human diagnostic laboratories, the former has not been routinely applied to the diagnosis of penaeid shrimp diseases and the latter has yet to be developed, despite considerable research and development efforts that have spanned the past 40 years. No continuous shrimp cell lines, or lines from other crustaceans, have been developed. Hence, when molecular methods began to be routinely applied to the diagnosis of infectious diseases in humans and domestic animals in the mid- to late 1980s, the technology was applied to the diagnosis of certain important diseases of penaeid shrimp for which only classical diagnostic methods were previously available. A DNA hybridization assay for the parvovirus IHHNV was the first molecular test developed for a shrimp disease. This was followed within a year by the first PCR test for MBV, an important baculovirus disease of shrimp. Today, shrimp disease diagnostic laboratories routinely use molecular tests for diagnostic and surveillance purposes for most of the important penaeid shrimp diseases.

Animal Diseases↗

PubMed2005

Comparison of lethal versus non-lethal sample sources for the detection of infectious salmon anemia virus (ISAV).

The emergence of infectious salmon anemia virus (ISAV) in Canada and the USA has led to the establishment of ISAV surveillance programs for cultured Atlantic salmon (Salmo salar L.) and wild fish species, including Atlantic salmon. Current testing procedures for ISAV consist of viral culture, reverse-transcription polymerase chain reaction (RT-PCR) and indirect fluorescent antibody testing (IFAT), and require lethal sampling. As the focus of this study, blood was evaluated as a possible non-lethal sample source for ISAV diagnostic screening by viral culture and RT-PCR. Tissue samples (consisting of kidney/spleen for viral culture or kidney only for RT-PCR), blood and, to a lesser extent, mucus were tested from Atlantic salmon survivors of laboratory ISAV infection trials and moribund fish from marine salmon grow-out facilities participating in a USDA-sponsored surveillance program. The trial fish represented a potential carrier population, while the surveillance fish were composed of moribund individuals from ISA clinical sites. Sample sources and diagnostic techniques were compared. Blood compared well to tissue samples for viral culture and produced a greater number of positives than did kidney samples for ISAV detection by RT-PCR. RT-PCR using both kidney and blood samples was determined to be a more sensitive assay than viral isolation. Mucus did not perform well in either assay compared to the other sample sources. Blood appears to be a reliable non-lethal sample source for the detection of ISAV by viral culture and RT-PCR in both moribund and asymptomatic fish.

Animals↗

PubMed2004

Eye fluke-induced cataract formation in fish: quantitative analysis using an ophthalmological microscope.

We examined the parasite-induced cataract formation in rainbow trout (Oncorhynchus mykiss) using slit-lamp microscopy to determine the relationship between cataract intensity and number of Diplostomum spathaceum parasites that were established in the lens. Cataract intensity increased significantly with parasite burden, but was also affected by the pattern of exposure to the parasite cercariae. The slit-lamp methodology proved useful in scoring the cataracts since it provides a 3-dimensional view into the lens and gives an actual picture of the location and intensity of the cataracts, which allows detailed investigations of mechanisms underlying cataract formation in various fish species. Potential applications of the method in fish farming and parasitological studies are discussed.

Animals↗

PubMed2001

Age-related changes in hematology and plasma chemistry values of hybrid striped bass (Morone chrysops X Morone saxatilis).

Hybrid striped bass (Morone chrysops X Morone saxatilis ) are an important aquaculture species yet there are few diagnostic tools available to assess their health. Hematology and clinical chemistry analyses are not used extensively in fish medicine due to the lack of reference intervals for various fish species, and because factors such as age can affect blood values. There is little published information regarding age-related changes in blood values of juvenile fish. It is important to evaluate juvenile fish, as this is the time they are raised in aquaculture settings. Determining age-related changes in the blood values of fishes would further develop clinical pathology as a diagnostic tool, enhancing both fish medicine and the aquaculture industry. The results of standard hematology and clinical chemistry analysis were evaluated in juvenile hybrid striped bass at 4, 6, 9, 15, and 19 months of age. Values for PCV and RBC indices were significantly lower, and plasma protein concentration was significantly higher in younger fish. Total WBC and lymphocyte counts were significantly higher in fish at 6 and 9 months of age, while neutrophil and monocyte counts were higher at 6, 9, and 15 months. Eosinophil counts were significantly higher in 9-month-old fish. The majority of hematologic values fell within previously established reference intervals, indicating that only slight modification to the intervals is necessary for evaluating hematologic results of hybrid striped bass at different ages. The following analytes deviated sufficiently from adult reference intervals to warrant separate reference values: plasma protein concentration at 4 months, WBC and lymphocyte counts at 15 and 19 months, and thrombocyte-like-cells at 9 months of age. Values for most biochemical analytes were significantly different among age groups except for creatinine and potassium concentrations. Comparisons with reference intervals were not made for biochemical analytes, because established reference intervals were not available. Age-related changes in hematologic and biochemical values of striped bass were similar to those reported for rainbow trout and mammals.

Journal Article↗

PubMed1995

Future of biotechnology-based control of disease in marine invertebrates.

Infectious disease is the single most devastating problem in mollusc and shrimp aquaculture. Pathogens causing the greatest problems have been identified as viruses, prokaryotes, and protozoans. Two approaches employing methods of biotechnology have been proposed to prevent, manage, and control mollusc and shrimp diseases. The first is development of a diagnostic scheme for detection and identification of pathogens, using molecular probes. This offers the opportunity for prophylactic measures to be taken. Molecular probes have been prepared for the major pathogens of molluscs, but in the case of shrimp pathogens, only a few are available. Monoclonal antibodies have also been prepared and are used in immunodiagnosis, e.g., immunofluorescence detection. Such diagnostic tools are relatively new to aquaculture, but have enormous potential. A second approach to the control of disease in marine invertebrates, notably shrimp, involves use of genetically transformed strains resistant to specific pathogens. Pathogen-resistant transgenic animals have been developed, but such research has only just begun for molluscs and shrimp. Transfection methods applied to mollusc and shrimp embryos have been successful, with preliminary data showing efficiency of heterologous promoters in controlling expression of reporter genes. Other transformation systems also show promise, including transposable elements and densoviruses.

Animal Diseases↗

PubMed2002

Penaeid (Penaeus japonicus) lymphoid cells replicate by cell division in vitro.

Penaeid cell culture has gained much attention as a potential model to facilitate researches on the characterization of the virus and to develop more sophisticated and improved diagnostic procedures for use in the aquaculture industry. However, to date, cell division processes of cultured penaeid cells have not been found, which is suggested as one of the reasons that block the establishment of the continuous penaeid cell lines. We reported here the cell division processes of cultured lymphoid cells of Penaeus japonicus. The culture medium used was based on M199 and was modified by supplementing saline components. Cultures were incubated at 25 degrees C, and 5% CO2 was supplemented. In primary cultured lymphoid cells, dividing cells in different shapes were found. Cell division processes of 12 dividing lymphoid cells were tracked. After cell division, their daughter cells turned into fibroblast-like or epithelioid cells. These results proved that the culture conditions used were suitable for lymphoid cells of I japonicus to proliferate in vitro and that cultured lymphoid cells still had the ability to carry out cell division. These findings would give light to the establishment of continuous penaeid cell lines and would also provide us with the knowledge of cell division processes of the penaeid.

Animals↗

PubMed2000

Diagnosis of Penaeus monodon-type baculovirus by PCR and by ELISA of occlusion bodies.

The black tiger prawn Penaeus monodon is a valuable aquaculture product in Taiwan. Two specific diagnostic methods were established for P. monodon-type baculovirus, one using polymerase chain reaction (PCR) technology and the other enzyme-linked immunosorbent assay (ELISA) technology. Monodon-type baculovirus (MBV) was purified by sucrose gradient centrifugation from occlusion bodies of MBV-infected postlarvae of P. monodon. MBV DNA was subsequently purified from the occlusion bodies and its presence was confirmed by PCR using primers of the polyhedrin gene. Based on conserved sequences of the DNA polymerase genes of Autographa californica nuclear polyhedrosis virus (AcMNPV) and Lymantria dispar nuclear polyhedrosis virus (LdMNPV), primers were designed and synthesized to yield a 714 bp PCR fragment from MBV. However, the sequence of this fragment revealed low homology with that of LdMNPV and AcMNPV. From the DNA sequence of this fragment, a second set of primers was designed, and using these primers, a 511 bp DNA fragment was amplified only when MBV DNA was the template. DNA templates from AcMNPV, white spot syndrome diseased shrimp, or PMO cells (a cell line derived from the Oka organ of Penaeus monodon) did not give any amplified DNA fragment. Therefore, this primer pair was specific for the diagnosis of MBV. By using intraspleenic immunization of rabbits with purified MBV occlusion bodies, a polyclonal rabbit antiserum against MBV was obtained. This antiserum could detect nanogram levels of MBV, but did not cross react with white spot syndrome virus (WSSV), homogenates of PMO cells, postlarvae, hepatopancreatic tissue or intestinal tissue of black tiger prawns by competitive ELISA. This sensitive method could detect MBV even in tissue homogenates.

Animals↗

PubMed2026

Gravity-driven millifluidic platform for magnetic solid-phase extraction of Enterocytozoon hepatopenaei DNA from complex shrimp hepatopancreas.

Effective detection of Enterocytozoon hepatopenaei (EHP) in aquaculture is currently hindered by the lack of field-deployable extraction methods capable of processing complex, inhibitor-rich hepatopancreatic tissue. This study presents a gravity-driven millifluidic platform for the rapid extraction of EHP genomic DNA using an optimized, surfactant-compatible magnetic solid-phase extraction (MSPE) chemistry. Utilizing 5% PEG 8000 and 2.0 M NaCl, the platform facilitates the selectively capture of DNA from inhibitor-rich crustacean lysates. The 3D-printed device employs a tilting rocking plate to generate passive, gravity-driven flow, maintaining homogeneous magnetic bead suspension and maximizing solid-phase capture efficiency without external pumps. The integrated platform achieved a DNA yield of 2804.33 ± 15.31 ng/μL, a 5.9-fold increase over manual magnetic bead extraction. TaqMan quantitative PCR (qPCR) validation targeting the EHP SSU rRNA gene was developed. Using a standard curve spanning 101 to 107 plasmid copies (Ct = -3.611 log10 [copy] + 42.309, R2 = 0.998, amplification efficiency 89.2%), the on-chip MSPE achieved a validated analytical limit of detection (LOD) of 1 spore per reaction (100% detection rate, n = 21), whereas a commercial CTAB-based DNA extraction kit failed to achieve a validated LOD even at 10 spores (85.7%, 18/21). Nested PCR targeting the SWP gene was employed for field evaluation. A pilot study across two cohorts (N = 40) demonstrated consistent detection of confirmed EPH-positive cases; however, the small sample size precludes definitive diagnostic accuracy claims. With a total processing time under 30 min, this platform provides a high-efficiency extraction module. Future work will couple the device with isothermal amplification (e.g., LAMP or RPA) to realize a sample-to-answer system for resource-limited aquaculture.

Aquaculture diagnostics↗

PubMed2002

Quantitative assay for measuring the Taura syndrome virus and yellow head virus load in shrimp by real-time RT-PCR using SYBR Green chemistry.

Taura syndrome virus (TSV) and yellow head virus (YHV) are the two RNA viruses infecting penaeid shrimp (Penaeus sp.) that have caused major economic losses to shrimp aquaculture. A rapid and highly sensitive detection and quantification method for TSV and YHV was developed using the GeneAmp 5700 Sequence Detection System and SYBR Green chemistry. The reverse transcriptase polymerase chain reaction (RT-PCR) mixture contained a fluorescent dye, SYBR Green, which exhibits fluorescence enhancement upon binding to double strand cDNA. The enhancement of fluorescence was found to be proportional to the initial concentration of the template cDNA. A linear relationship was observed between input plasmid DNA and cycle threshold (C(T)) values for 10(6) down to a single copy of both viruses. To control for the variation in sample processing and in reverse transcription reaction among samples, shrimp beta-actin and elongation factor-1alpha (EF-1alpha) genes were amplified in parallel with the viral cDNA. The sensitivity and the efficiency of amplification of EF-1alpha was greater than beta-actin when compared to TSV and YHV amplification efficiency suggesting that EF-1alpha is a better internal control for the RT-PCR detection of TSV and YHV. In addition, sample to sample variation in EF-1alpha C(T) value was lower than the variation in beta-actin C(T) value of the corresponding samples. The specificity of TSV, YHV, EF-1alpha and beta-actin amplifications was confirmed by analyzing the dissociation curves of the target amplicon. The C(T) values of TSV and YHV samples were normalized against EF-1alpha C(T) values for determining the absolute copy number from the standard curve of the corresponding virus. The method described here is highly robust and is amenable to high throughput assays making it a useful tool for diagnostic, epidemiological and genetic studies in shrimp aquaculture.

Actins↗

PubMed2004

Detection of white spot syndrome virus in shrimp by loop-mediated isothermal amplification.

Loop-mediated isothermal amplification (LAMP) method is a novel, sensitive and rapid technique which can be applied for disease diagnosis in aquaculture. Using the LAMP method, a highly specific and sensitive diagnostic system for white spot syndrome virus (WSSV) detection was designed. A set of four primers, two outer and two inner primers, were designed from WSSV genome DNA. Reaction time and temperatures were optimized for 60 min at 65 degrees C, respectively. The detection limit (DL) using the LAMP method was up to 1 fg, when compared to 10 fg by nested polymerase chain reaction (PCR). Thus, standardized LAMP procedure was used to detect the presence of WSSV in the heart, stomach and lymphoid organ from infected shrimp. The study has developed a diagnostic procedure which is a rapid and highly sensitive for WSSV detection in shrimp.

Animals↗

PubMed2005

Study of perkinsosis in the carpet shell clam Tapes decussatus in Galicia (NW Spain). II. Temporal pattern of disease dynamics and association with clam mortality.

Temporal dynamics of the infection by Perkinsus olseni in a clam (Tapes decussatus) bed was studied over 5 yr (March 1996 to December 2000). Diagnostic techniques were compared to assess their suitability for epizootiological purposes. A technique based on incubation of 2 gill lamellae in Ray's fluid thioglycollate medium (RFTM) was more sensitive, quicker and cheaper than examination of histological sections. Incubation of the whole-clam soft tissues in RFTM allowed detection of very light infections that were not detected with incubation of only 2 gill lamellae. Nevertheless, the correlation between the infection intensity estimated by both RFTM incubations was high. Infection intensity was significantly and positively correlated with clam size/age. No infected clam smaller than 20 mm was found. There was an annual pattern of infection involving lower mean infection intensity and prevalence in winter and higher values for both variables from spring to autumn, with 2 main annual peaks in spring and late summer-early autumn. This temporal pattern was significantly associated with the seawater temperature. The annual spring peak of infection intensity occurred when seawater temperature was around 15 degrees C. Monthly mortality in the clam bed peaked in spring and summer--after peaks of P. olseni infection intensity and concurrently with high seawater temperature. A comparison of percentage mortality between clams from 2 sources (a perkinsosis-affected and a non-affected area) placed in the same clam bed revealed significantly higher mortality in the clams originating from the perkinsosis-affected area.

Age Factors↗

PubMed2005

Sensitive and rapid detection of infectious hypodermal and hematopoietic necrosis virus (IHHNV) in shrimps by loop-mediated isothermal amplification.

A method for nucleic acid amplification, loop-mediated isothermal amplification (LAMP) is a novel, sensitive and rapid technique, which can be applied for disease diagnosis in aquaculture. Using the LAMP method, a highly specific and sensitive diagnostic system for infectious hypodermal and hematopoietic necrosis virus (IHHNV) detection was designed. A set of four primers was designed by targeting the IHHNV genome DNA. By the detection system, target DNA was amplified and visualized on agarose gel within 60min under isothermal condition at 64 degrees C. Without gel electrophoresis, the LAMP amplicon was visualized directly in the reaction tube by addition of SYBR Green I for a naked-eye inspection. The LAMP reaction was also assessed by the white turbidity of magnesium pyrophosphate (a by-product of LAMP) in the tube. The assay had a detection limit of 5-500 copies of DNA template with gel electrophoresis, SYBR Green I and white turbidity with naked-eye inspection. The detection sensitivity of LAMP was 100-fold higher than the PCR. A diagnostic procedure which is rapid and highly sensitive was developed for IHHNV detection.

Animals↗

PubMed2001

The role of epidemiology in the prevention, diagnosis, and control of infectious diseases of fish.

Epidemiologic methods are essential to understanding infectious diseases in aquaculture. Unfortunately, many of these methods are poorly understood or not utilized by fish-health scientists and aquaculturists -- often because of the lack of contact with epidemiologists who are willing to investigate fish diseases. In this paper, we describe direct interactions between epidemiologists and fish-health specialists that have resulted in an improved understanding of the causes and management of infectious diseases in aquaculture. We focus on risk-factor studies, risk analysis and infectious-disease modeling, evaluation of diagnostic tests and experimental studies. We also describe characteristics of confined fish populations that make them ideal for developing and testing epidemiologic models and the theoretical and practical challenges of designing and conducting epidemiologic studies in fish farms. Throughout our presentation, emphasis is given to characteristics, opportunities and problems associated mainly with conducting epidemiologic studies to intensive aquaculture systems. We conclude that the development of increased cooperation among epidemiologists, fish-health scientists and aquaculturists will be mutually beneficial and, therefore, efforts for such collaboration should be initiated from all parties involved.

Animal Diseases↗

PubMed2005

Disease and health management in Asian aquaculture.

Asia contributes more than 90% to the world's aquaculture production. Like other farming systems, aquaculture is plagued with disease problems resulting from its intensification and commercialization. This paper describes the various factors, providing specific examples, which have contributed to the current disease problems faced by what is now the fastest growing food-producing sector globally. These include increased globalization of trade and markets; the intensification of fish-farming practices through the movement of broodstock, postlarvae, fry and fingerlings; the introduction of new species for aquaculture development; the expansion of the ornamental fish trade; the enhancement of marine and coastal areas through the stocking of aquatic animals raised in hatcheries; the unanticipated interactions between cultured and wild populations of aquatic animals; poor or lack of effective biosecurity measures; slow awareness on emerging diseases; the misunderstanding and misuse of specific pathogen free (SPF) stocks; climate change; other human-mediated movements of aquaculture commodities. Data on the socio-economic impacts of aquatic animal diseases are also presented, including estimates of losses in production, direct and indirect income and employment, market access or share of investment, and consumer confidence; food availability; industry failures. Examples of costs of investment in aquatic animal health-related activities, including national strategies, research, surveillance, control and other health management programmes are also provided. Finally, the strategies currently being implemented in the Asian region to deal with transboundary diseases affecting the aquaculture sector are highlighted. These include compliance with international codes, and development and implementation of regional guidelines and national aquatic animal health strategies; new diagnostic and therapeutic techniques and new information technology; new biosecurity measures including risk analysis, epidemiology, surveillance, reporting and planning for emergency response to epizootics; targeted research; institutional strengthening and manpower development (education, training and extension research and diagnostic services).

Animals↗

PubMed2005

Characterization and mapping of monoclonal antibodies against the Sleeping disease virus, an aquatic alphavirus.

Sleeping disease virus (SDV) is an emerging pathogen in salmonid aquacultures, the impact of which is underestimated to date due to the lack of efficient diagnostic tools. To better characterize this new aquatic alphavirus and to make molecular tools available, a panel of monoclonal antibodies (mAbs) directed against SDV non-structural and structural proteins has been generated by immunizing mice with SDV-specific recombinant proteins overexpressed in Escherichia coli as antigens. So far, mAbs against nsP1, nsP3, E2 and E1 SDV proteins have been produced and their reactivity has been characterized by Western blot, radioimmunoprecipitation and indirect immunofluorescence assays. In addition, protein domains recognized by each mAb have been determined by immunofluorescence assay on truncated expressed SDV-derived proteins. Finally, one mAb directed against the E1 glycoprotein has been evaluated as a potential tool to be used in immunohistochemistry assay on experimentally infected trout.

Alphavirus↗