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COELOMIC STEATITIS IN TENTACLED SNAKES ( ERPETON TENTACULATUM). J Zoo Wildl Med 2021; 52:1061-1073. [PMID: 34687525 DOI: 10.1638/2020-0210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2021] [Indexed: 11/21/2022] Open
Abstract
A retrospective study revealed seven cases of coelomic steatitis in adult tentacled snakes (Erpeton tentaculatum), including two males and five females, between May 2014 and August 2020. Common clinical signs included death after unusual floating, generalized weakness, inappetence, reduced body condition, coelomic distension, and reproductive pathology in females. Hematology of one specimen revealed marked monocytosis and lymphocytosis with mild heterophilia (chronic and active inflammation). Gross examination identified variable degrees of intracoelomic fat necrosis in all snakes. Consistent histopathologic features included necrotic adipocytes, lipid saponification, lipofuscin/ceroid deposition, granulomatous inflammation, and multinucleated giant cells (Langhans type). Three females exhibited intralesional yolk fluid associated with periovarian steatitis. Hepatic lipidosis was the second most frequent pathologic finding. Thawed frozen lesser sand eels (Ammodytes tobianus) were fed during this period, stored in vacuum-sealed or opened packets at -18°C (frozen). After the death of the last specimen, vitamin E concentrations and peroxide values of the diet were analyzed. For the sealed and opened frozen batches, respectively, vitamin E concentrations were 0.71 and 0.49 mg/100 g (compared with 4 to 8 mg/100 g in average, fresh, raw mixed eel species samples) and peroxide values were 62.5 and 48.6 meq/kg (exceeding the acceptable peroxide values of 8 meq/kg for fish oils). This case study represents the first report of coelomic steatitis in tentacled snakes of unconfirmed etiology but with a putative association with feeding a long-term frozen-stored sand eel diet containing low vitamin E concentrations and fish oils with high peroxide values at time of analysis.
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Huchzermeyer KDA, Woodborne S, Osthoff G, Hugo A, Hoffman AC, Kaiser H, Steyl JCA, Myburgh JG. Pansteatitis in polluted Olifants River impoundments: nutritional perspectives on fish in a eutrophic lake, Lake Loskop, South Africa. JOURNAL OF FISH DISEASES 2017; 40:1665-1680. [PMID: 28493486 DOI: 10.1111/jfd.12633] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 02/10/2017] [Accepted: 02/12/2017] [Indexed: 06/07/2023]
Abstract
This study compares the aetiology of pansteatitis in Lake Loskop, relative to two other impoundments along the Olifants River. Macroscopic and microscopic pathology, age determination and analysis of stomach content, fatty acids and stable isotopes explain the high prevalence of pansteatitis in Oreochromis mossambicus (Peters) and several other species in Lake Loskop. All the dietary indicator comparisons between pansteatitis-affected and healthy fish fail to support a systemic cause. Pansteatitis in Lake Loskop was linked to size and weight of O. mossambicus, but not to ontogenic age. Fish in Lake Loskop showed abnormally high omega-3 to omega-6 fatty acid ratios normally only found in marine fish with no significant difference in degree of assimilation of these fatty acids between pansteatitis-affected and healthy fish. This explains the vulnerability to, but not the occurrence of, pansteatitis. As a cause for the pansteatitis, these results point towards sporadic vitamin E-depleting trigger events, known sporadic fish die-off occurrences that provide surviving fish with a rich source of rancid fats on which to scavenge. The mechanism ties pansteatitis to eutrophication and trophic cascade effects, the intrinsic drivers of the disease and suggests an adaptive management strategy that might be applied by relevant conservation authorities.
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Affiliation(s)
- K D A Huchzermeyer
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
- Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa
| | - S Woodborne
- iThemba LABS, Johannesburg, South Africa
- Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - G Osthoff
- Microbial Biochemical and Food Biotechnology, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein, South Africa
| | - A Hugo
- Microbial Biochemical and Food Biotechnology, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein, South Africa
| | - A C Hoffman
- Scientific Services, Mpumalanga Tourism and Parks Agency, Nelspruit, South Africa
| | - H Kaiser
- Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa
| | - J C A Steyl
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - J G Myburgh
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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Dabrowski J, Oberholster P, Steyl J, Osthoff G, Hugo A, Power DM, van Wyk JH. Thyroid function of steatitis-affected Mozambique tilapia Oreochromis mossambicus from a sub-tropical African reservoir. DISEASES OF AQUATIC ORGANISMS 2017; 125:101-113. [PMID: 28737156 DOI: 10.3354/dao03138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Thyroid function and nutritional indicators were measured in obese, steatitis-affected Mozambique tilapia Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. Plasma thyroid hormones (especially T3) and thyroid follicle histomorphology revealed high levels of activity in every aspect of the thyroid cascade measured in fish from LR compared to a reference population of steatitis-free fish. Concurrent measurements of nutritional state including plasma lipids, liver lipid content and hepatocyte size showed that fish from LR had significant energy stores indicative of abundant nutritional intake. There were distinct sex and seasonal differences, with the highest plasma lipids and T3 levels observed in steatitis-affected females during spring and summer. Positive correlations were observed between plasma lipids (especially cholesterol) and T3 concentrations in fish from both populations, indicating a link between lipid metabolism and thyroid function. There was no direct evidence of thyroid disruption, but this cannot be ruled out until further research determines the factors that underlie the homeostatic shift leading to elevated plasma and liver lipids and T3 levels in steatitis-affected tilapia.
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Affiliation(s)
- J Dabrowski
- Sustainability Research Unit, Nelson Mandela Metropolitan University, Private Bag x6531, George 6530, South Africa
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Bowden JA, Cantu TM, Chapman RW, Somerville SE, Guillette MP, Botha H, Hoffman A, Luus-Powell WJ, Smit WJ, Lebepe J, Myburgh J, Govender D, Tucker J, Boggs ASP, Guillette LJ. Predictive Blood Chemistry Parameters for Pansteatitis-Affected Mozambique Tilapia (Oreochromis mossambicus). PLoS One 2016; 11:e0153874. [PMID: 27115488 PMCID: PMC4846142 DOI: 10.1371/journal.pone.0153874] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/05/2016] [Indexed: 11/19/2022] Open
Abstract
One of the largest river systems in South Africa, the Olifants River, has experienced significant changes in water quality due to anthropogenic activities. Since 2005, there have been various “outbreaks” of the inflammatory disease pansteatitis in several vertebrate species. Large-scale pansteatitis-related mortality events have decimated the crocodile population at Lake Loskop and decreased the population at Kruger National Park. Most pansteatitis-related diagnoses within the region are conducted post-mortem by either gross pathology or histology. The application of a non-lethal approach to assess the prevalence and pervasiveness of pansteatitis in the Olifants River region would be of great importance for the development of a management plan for this disease. In this study, several plasma-based biomarkers accurately classified pansteatitis in Mozambique tilapia (Oreochromis mossambicus) collected from Lake Loskop using a commercially available benchtop blood chemistry analyzer combined with data interpretation via artificial neural network analysis. According to the model, four blood chemistry parameters (calcium, sodium, total protein and albumin), in combination with total length, diagnose pansteatitis to a predictive accuracy of 92 percent. In addition, several morphometric traits (total length, age, weight) were also associated with pansteatitis. On-going research will focus on further evaluating the use of blood chemistry to classify pansteatitis across different species, trophic levels, and within different sites along the Olifants River.
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Affiliation(s)
- John A. Bowden
- National Institute of Standards and Technology (NIST), Material Measurement Laboratory, Chemical Sciences Division, Environmental Chemical Sciences Group, Hollings Marine Laboratory, Charleston, South Carolina, United States of America
- * E-mail:
| | - Theresa M. Cantu
- Departments of Obstetrics and Gynecology, Medical University of South Carolina (MUSC), Charleston, South Carolina, United States of America
| | - Robert W. Chapman
- Marine Resources Research Institute, South Carolina Department of Natural Resources, Hollings Marine Laboratory, Charleston, South Carolina, United States of America
| | - Stephen E. Somerville
- Departments of Obstetrics and Gynecology, Medical University of South Carolina (MUSC), Charleston, South Carolina, United States of America
| | - Matthew P. Guillette
- Departments of Obstetrics and Gynecology, Medical University of South Carolina (MUSC), Charleston, South Carolina, United States of America
| | - Hannes Botha
- Scientific Services, Mpumalanga Tourism and Parks Agency, Nelspruit, South Africa
- Department of Biodiversity, University of Limpopo, Sovenga, South Africa
| | - Andre Hoffman
- Scientific Services, Mpumalanga Tourism and Parks Agency, Nelspruit, South Africa
| | | | - Willem J. Smit
- Department of Biodiversity, University of Limpopo, Sovenga, South Africa
| | - Jeffrey Lebepe
- Department of Biodiversity, University of Limpopo, Sovenga, South Africa
| | - Jan Myburgh
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Danny Govender
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
- Scientific Services, South African National Parks, Skukuza, South Africa
| | - Jonathan Tucker
- Marine Resources Research Institute, South Carolina Department of Natural Resources, Hollings Marine Laboratory, Charleston, South Carolina, United States of America
| | - Ashley S. P. Boggs
- National Institute of Standards and Technology (NIST), Material Measurement Laboratory, Chemical Sciences Division, Environmental Chemical Sciences Group, Hollings Marine Laboratory, Charleston, South Carolina, United States of America
| | - Louis J. Guillette
- Departments of Obstetrics and Gynecology, Medical University of South Carolina (MUSC), Charleston, South Carolina, United States of America
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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Truter JC, van Wyk JH, Oberholster PJ, Botha AM, Luus-Powell WJ. The expression of selected genes linked to metabolic homeostasis in obese pansteatitis-suffering Mozambique tilapia, Oreochromis mossambicus (Peters). JOURNAL OF FISH DISEASES 2016; 39:69-85. [PMID: 25413848 DOI: 10.1111/jfd.12324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 10/06/2014] [Accepted: 10/06/2014] [Indexed: 06/04/2023]
Abstract
The Oreochromis mossambicus (Peters) population inhabiting Lake Loskop, South Africa, is characterized by a high incidence of obesity and pansteatitis. We investigated potential links between the impaired health of Lake Loskop O. mossambicus and the endocrine system by assessing the expression of selected genes associated with the thyroid and adrenal endocrine axes as well as peroxisome proliferator-activated receptor gamma (pparg). Moreover, contaminant-induced thyroid and/or metabolic modulation in Lake Loskop water was evaluated using juvenile O. mossambicus in laboratory exposures. The expression of thyroid hormone receptor alpha (thra) and type 2 deiodinase (dio2) was higher in Lake Loskop O. mossambicus than fish from another population, suggesting a degree of thyroid disruption. The altered gene expression may be a consequence, rather than cause of obesity. Expression of dio2 and pparg was higher in juvenile O. mossambicus exposed to unfiltered compared to filtered lake water, and our data suggest fasting as causative factor. Micro-organism abundance can therefore be a confounding factor in studies applying molecular markers to test for thyroid modulation by environmental waters. Pansteatitis was not a significant source of variance in the expression of any of the genes investigated, suggesting that the disease is not associated with disrupted endocrine signalling.
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Affiliation(s)
- J C Truter
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - J H van Wyk
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - P J Oberholster
- CSIR Natural Resources and the Environment, Stellenbosch, South Africa
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - A-M Botha
- Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - W J Luus-Powell
- Department of Biodiversity, University of Limpopo, Sovenga, South Africa
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PANSTEATITIS OF UNKNOWN ETIOLOGY ASSOCIATED WITH LARGE-SCALE NILE CROCODILE (CROCODYLUS NILOTICUS) MORTALITY IN KRUGER NATIONAL PARK, SOUTH AFRICA: PATHOLOGIC FINDINGS. J Zoo Wildl Med 2013; 44:899-910. [DOI: 10.1638/2012-0264r.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Huchzermeyer KDA, Osthoff G, Hugo A, Govender D. Comparison of the lipid properties of healthy and pansteatitis-affected African sharptooth catfish, Clarias gariepinus (Burchell), and the role of diet in pansteatitis outbreaks in the Olifants River in the Kruger National Park, South Africa. JOURNAL OF FISH DISEASES 2013; 36:897-909. [PMID: 23634747 DOI: 10.1111/jfd.12010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 08/23/2012] [Accepted: 08/24/2012] [Indexed: 06/02/2023]
Abstract
Pansteatitis has been identified in wild populations of sharptooth catfish, Clarias gariepinus (Burchell), and Nile crocodiles, Crocodylus niloticus Laurenti, inhabiting the same waters in the Olifants River Gorge in the Kruger National Park, South Africa. Mesenteric and pectoral fat tissue was investigated microscopically and by fatty acid analysis in healthy and pansteatitis-affected catfish from both captive and wild populations. Variation in fatty acid composition between pectoral and mesenteric fat was noted. Composition of mesenteric fat differed between fish from various localities as a result of differences in diet. Pansteatitis in the captive population, resulting from ingestion of high amounts of dietary oxidized fat, reflected higher levels of unsaturated fatty acids within the mesenteric fat. Mesenteric fat of pansteatitis-affected wild catfish was characterized by an increase in moisture content, a decrease in fat content and a decrease in stearic and linoleic acids. The n-3 to n-6 fatty acid ratio of mesenteric fat was higher in pansteatitis-affected wild catfish than in healthy catfish from the same locality, reflecting higher polyunsaturated fat intake by pansteatitis-affected fish. The possible role of alien, invasive, phytoplankton-feeding silver carp, Hypophthalmichthys molitrix (Valenciennes), in the aetiology of pansteatitis in both catfish and crocodiles in the Olifants Gorge is discussed.
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Affiliation(s)
- K D A Huchzermeyer
- Sterkspruit Veterinary Clinic, Lydenburg, South Africa; Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
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Orós J, Monagas P, Calabuig P, Luzardo OP, Camacho M. Pansteatitis associated with high levels of polychlorinated biphenyls in a wild loggerhead sea turtle Caretta caretta. DISEASES OF AQUATIC ORGANISMS 2013; 102:237-242. [PMID: 23446973 DOI: 10.3354/dao02550] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We describe the morphologic and toxicological findings in a case of pansteatitis in a stranded loggerhead sea turtle Caretta caretta. At necropsy, a large amount of adipose tissue in the celomic cavity showing very firm, yellow to orange irregular formations was observed. Histological lesions ranged from the infiltration of necrotic fat by scarce multinucleated giant cells and numerous macrophages containing xylene-insoluble lipopigment inclusions to the presence of several granulomas characterized by an irregular central necrotic area consisting of lipopigment surrounded by numerous multinucleated giant cells. Microbiological cultures were negative. Celomic fat was analyzed for PCBs and DDTs, resulting in very high levels of PCB 138, 153, 180 209 (3170, 2830, 980 and 1190 ng g-1, respectively). Although a nutritional cause cannot be ruled out, the high levels of PCBs detected in the celomic fat could have induced lipid peroxidation in adipocytes, resulting in cell damage, deposition of ceroid pigment and inflammatory response. This is the first report of pansteatitis in a wild sea turtle.
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Affiliation(s)
- J Orós
- Department of Morphology, University of Las Palmas de Gran Canaria, Las Palmas, Spain
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Huchzermeyer KDA. Prevalence of pansteatitis in African sharptooth catfish, Clarias gariepinus (Burchell), in the Kruger National Park, South Africa. J S Afr Vet Assoc 2012; 83:916. [PMID: 23327137 DOI: 10.4102/jsava.v83i1.916] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 08/31/2012] [Accepted: 09/11/2012] [Indexed: 11/01/2022] Open
Abstract
Pansteatitis was confirmed in sharptooth catfish, Clarias gariepinus (Burchell), from three main locations within the Kruger National Park (KNP); the Olifants River Gorge, Engelhard Dam on the Letaba River and from the Sabie River in the Sabiepoort. An increasing prevalence of pansteatitis was observed in catfish during repeated samplings from the Olifants Gorge from 2009 to 2011 and co-existence of old and recent lesions indicated on-going incitement of pansteatitis. Only a low prevalence of pansteatitis was observed in catfish sampled from the Olifants River upstream of the Gorge in the KNP and no pansteatitis was observed in catfish sampled from a rain-filled dam not connected to the Olifants River. Common to both the Olifants Gorge and the Sabiepoort is the damming of the rivers in Mozambique to form lakes Massingir and Corumana respectively. Anthropogenic activities resulting in potential pollution of the rivers differ greatly between these two catchments, providing argument against a primary pollution-related aetiology of the pansteatitis found at these two sites. Compared with other sites, analysis of stomach contents of catfish from the Olifants Gorge and the Sabiepoort strongly suggested that consumption of a predominantly fish diet was associated with the development of pansteatitis in these fish. In a farmed population of catfish used as positive control, development of pansteatitis could be ascribed to consumption of rancid fish waste from a trout slaughterhouse. In the Olifants Gorge, alien invasive silver carp, Hypophthalmychthys molitrix (Valenciennes), seasonally migrate upstream out of Lake Massingir to spawn. This schooling species is an obligate phytoplankton feeder with consequent high levels of adipose tissue n-3 polyunsaturated fatty acids. In the Olifants Gorge, at least, this may explain seasonal exposure to levels of polyunsaturated fats in the diets of catfish and crocodiles to which these animals are not adapted. The possible roles of diet, membrane lipid composition and metabolic rate of fish, sediment pollution and seasonal drop in environmental temperature in the pathogenesis of pansteatitis in the catfish are discussed. Further studies are needed to verify some of these speculations.
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Woodborne S, Huchzermeyer KDA, Govender D, Pienaar DJ, Hall G, Myburgh JG, Deacon AR, Venter J, Lübcker N. Ecosystem change and the Olifants River crocodile mass mortality events. Ecosphere 2012. [DOI: 10.1890/es12-00170.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
Under intensive culture conditions, fish are subject to increased stress owing to environmental (water quality and hypoxia) and health conditions (parasites and infectious diseases). All these factors have negative impacts on fish well-being and overall performance, with consequent economic losses. Though good management practices contribute to reduce stressor effects, stress susceptibility is always high under crowded conditions. Adequate nutrition is essential to avoid deficiency signs, maintain adequate animal performance and sustain normal health. Further, it is becoming evident that diets overfortified with specific nutrients [amino acids, essential fatty acids (FAs), vitamins or minerals] at levels above requirement may improve health condition and disease resistance. Diet supplements are also being evaluated for their antioxidant potential, as fish are potentially at risk of peroxidative attack because of the large quantities of highly unsaturated FAs in both fish tissues and diets. Functional constituents other than essential nutrients (such as probiotics, prebiotics and immunostimulants) are also currently being considered in fish nutrition aiming to improve fish growth and/or feed efficiency, health status, stress tolerance and resistance to diseases. Such products are becoming more and more important for reducing antibiotic utilization in aquafarms, as these have environmental impacts, may accumulate in animal tissues and increase bacterial resistance. This study reviews knowledge of the effect of diet nutrients on health, welfare and improvement of disease resistance in fish.
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Affiliation(s)
- A Oliva-Teles
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal.
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Huchzermeyer KDA, Govender D, Pienaar DJ, Deacon AR. Steatitis in wild sharptooth catfish, Clarias gariepinus (Burchell), in the Olifants and lower Letaba Rivers in the Kruger National Park, South Africa. JOURNAL OF FISH DISEASES 2011; 34:489-498. [PMID: 21675995 DOI: 10.1111/j.1365-2761.2011.01267.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Large numbers of adult Nile crocodiles, Crocodylus niloticus (Laurenti), died from pansteatitis during autumn and winter 2008 in the lower Letaba and Olifants River gorge in the Kruger National Park, South Africa. Consequently, the health status of fish from these waters was investigated. The study presents the pathological findings in fish inhabiting these rivers within the boundaries of the Park. Changes typical of steatitis were diagnosed in many of the larger specimens of sharptooth catfish, Clarias gariepinus (Burchell), caught within the Olifants River gorge. These fish carried large amounts of mesenteric fat with characteristic small brown granulomata within the adipose tissue. Necrosis and inflammation of the adipose tissues, with characteristic ceroid accumulation within the resultant granulomata and the associated aggregation of ceroid-containing macrophages, were demonstrated histologically and were typical of steatitis. Other changes included mild thickening and pallor of the gill tissues and swollen, orange, fatty livers. Focal hepatic lipidosis was demonstrated histologically, and special stains revealed storage of large amounts of iron in the livers. Blood smears revealed chromatin clumping in erythrocyte nuclei and nuclear and cell membrane irregularities. This is the first record of steatitis in wild-caught C. gariepinus.
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Roberts RJ, Agius C. Pan-steatitis in farmed northern bluefin tuna, Thunnus thynnus (L.), in the eastern Adriatic. JOURNAL OF FISH DISEASES 2008; 31:83-88. [PMID: 18234015 DOI: 10.1111/j.1365-2761.2007.00901.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Clinical, gross and histopathological investigations were carried out into large-scale mortalities on eastern Mediterranean bluefin tuna, Thunnus thynnus (L.), farms. Fish showed only nervous signs and darkened colour. At post-mortem the liver was bronze coloured and the pyloric area waxy in consistency. There was no evidence of any other gross pathology. Histopathology showed severe hepatic necrosis and lipidosis. Peri-pancreatic lipoid tissue was heavily infiltrated with an inflammatory round cell infiltrate. Fish on all three farms had been fed on a North African pilchard diet rather than traditional local or Baltic species. Once the diet was modified, losses ceased. A diagnosis of pan-steatitis as seen in other farmed fish species, as well as in terrestrial animals, on particular fish-based diets was made, although the actual factor within the diet which induced the inflammatory effect is not known.
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Affiliation(s)
- R J Roberts
- Hagerman Fish Culture Experiment Station, University of Idaho, Hagerman, ID 83332, USA.
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