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| − | {{Podcasts
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| − | |link = https://bloomsbury.mediacore.tv/podcasts/wikivet-english/cryptobiosis}}
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| − | {{Taxobox
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| − | |name = ''Cryptobia spp.''
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| − | |kingdom = Protista
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| − | |shttp://en.wikivet.net/index.php?title=Cryptobiosis&action=editub-kingdom =
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| − | |phylum = [[:Category:Protozoa|Protozoa]]
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| − | |super-class = Sarcomastigophora
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| − | |class =
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| − | |sub-class =
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| − | |super-order =
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| − | |order = Kinetoplastida
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| − | |sub-order =
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| − | |super-family =
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| − | |family = Cryptobiidae
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| − | |sub-family =
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| − | |genus = ''Cryptobia spp.''
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| − | |species =
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| − | }}
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| − | Caused By: '''''Cryptobia branchialis — C. iubilans — C. salmositica — C. bullocki — C. borreli''
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| − | ==Introduction==
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| − | Cryptobia species are '''bi-flagellated [[Protozoa|protozoan]]''' that infect a range of vertebrate and invertebrate hosts. A few species are known for causing disease as both '''endoparasites and ectoparasites of fish'''. ''C. branchialis'' is the only '''ectoparasite''' of the five pathogenic species listed above. They may be found on the '''body surface or gills''' of host fish while endoparasitic species may reside within the '''intestine or the blood'''. A couple of blood parasites have ectoparasitic life stages on the external body surface.
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| − | The parasites are '''oval or ribbon-like''' in shape with both flagellae attached to their anterior end. One flagellum is '''recurrent''' and ends freely at the posterior end of the cell. They also have a very prominent kinetoplast. Replication is by binary fission.<ref>Woo, P. T. K (1987) '''Cryptobia and cryptobiosis in fishes'''. ''Advances in Parasitology'', 26:199-237</ref>
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| − | ==Distribution==
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| − | '''Asia, North America and Eastern Europe''' and also in the '''Atlantic''' ocean in wild species.
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| − | ''C. bullocki'' is isolated in marine fish in the '''USA and Northern Gulf of Mexico'''.
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| − | ''C. iubilans'' is associated with the '''intestine''' and therefore transmitted '''faecally''', while ''C. salmositica, C. bullocki'' and ''C. borreli'' are '''haematozoic species''' and therefore '''transmitted by bloodfeeding leeches'''. Some are also found in surface '''mucus'''. ''C. salmositica'' has been diagnosed where no leeches were found so transmission is poorly understood<ref> Becker, C. D., Katz, M (1965) '''Distribution, ecology, and biology of the salmonid leech, Piscicola salmositica (Rhynchobdellae: Piscicolidae)'''. ''J Fisheries Research Board of Canada'', 22:1175-1195</ref>. It has been suggested that parasites enter the recipient fish via '''surface lesions or the gills'''. Transmission via the water in shared tanks is efficient and is only slightly reduced when infected and non-infected fish are separated by wire screens.
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| − | ==Signalment==
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| − | Many species of both '''marine and freshwater''' fish are infected. Although salmonids are often of prime concern, resident fish, such as flatfish in Chesapeake Bay are also affected. Interestingly, these native fish survive the disease if kept in water maintained at 10-13⁰C after infection but die if water is 5⁰ or below.
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| − | ''C. bullocki'' causes disease and mortality in '''marine''' fish. ''C. salmositica'' has also been found on fish in sea water. The remaining pathogenic species are '''parasitic to freshwater fish'''.
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| − | Leech numbers increase in '''November''' and so prevalence and severity of parasitaemia are higher in haematozoic infections during late Autumn and Winter in the northern hemisphere.<ref>Bower, S. M., Margolis, L (1984) '''Detection of infection and susceptibility of different Pacific salmon stocks (Oncorhynchus spp.) to the haemoflagellate Cryptobia salmositica'''. ''J Parasitology'', 70(2):273-278</ref>
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| − | ==Clinical Signs and Pathology==
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| − | === ''C. branchialis'' – Respiratory Ectoparasite ===
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| − | '''Gills''' of fish infected with ''C. branchialis'' are abnormally '''red''', their bodies are '''covered with copious mucus''' which often '''darkens''' shortly before death. Fish are '''anorexic''' and swim close to the water’s surface.<ref>Kuperman, B. I., Matey, V. E., Barlow, S. B (2002) '''Flagellate Cryptobia branchialis (Bodonida: Kinetoplastida), ectoparasite of tilapia from the Salton Sea'''. ''Hydrobiologia'', 473:93-102</ref> The parasite attaches to the gill epithelium using its '''recurrent flagellum'''. Death eventually occurs due to '''thrombus''' formation.
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| − | === ''C. iubilans'' – Gastrointestinal Endoparasite ===
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| − | ''C. iubilans'' causes '''lethargy, anorexia, stunted growth, emaciation and mortality''', which can take variable amounts of time, as short as one week, but usually less than 3 months. Multifocal '''granulomas''' form in the liver, spleen, kidney, stomach and intestine.
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| − | === ''C. salmositica'' – Haematozoic Endoparasite ===
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| − | '''Exophthalmia, splenomegaly, hepatomegaly, oedema, ascites, [[Anaemia|anaemia]] and marked emaciation''' are signs of infection with the blood-borne ''C. salmositica''. Anaemia is usually '''microcytic and hypochromic''', caused by '''haemolytic action of parasitic secretions (haemolysin, subsequently identified as a metalloprotease)''' and '''antigen release''' after immune destruction (immune complex driven). Obvious lesions are present in '''haematopoietic tissues''' of infected fish. '''Immunosuppression''' is also marked. Anorexia can be an important contributor to immunosuppression.
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| − | Infected fish are also '''more sensitive to environmental hypoxia''' due to the anaemia and occlusion of blood vessels by parasites and consequently impaired perfusion. This can be an important exacerbating factor of mortality when oxygen supply is already restricted due to overcrowding, slow flow or algal blooms.<ref>Woo, P. T. K., Wehnert, S. D (1986) '''Cryptobia salmositica: susceptibility of infected rainbow trout, Salmo gairdneri, to environmental hypoxia'''. ''Journal of Parasitology'', 72(3):392-396</ref>
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| − | Histopathological features include '''focal haemorrhages, vascular congestion and occlusion and oedematous changes''' in the renal glomeruli. Lesions can be present in the liver, gills and spleen also, and generalised inflammation progresses to mononuclear infiltration after 3 weeks. After this point, '''parasites are found extravascularly where they cause tissue necrosis.'''
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| − | === ''C. borreli'' – Haematozoic Endoparasite ===
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| − | This parasite also causes '''[[Anaemia|anaemia]]. Diffuse degenerate changes''' are seen on pathological examination, with glomerulitis and tubulonephrosis and necrotic foci in the liver. Infection eventually destroys 40% of the renal tubules, causing '''renal and osmoregulatory failure'''. Mitochondrial deterioration is seen in late infection.
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| − | === ''C. bullocki'' - Haematozoic Endoparasite ===
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| − | '''Anaemia, splenomegaly, lethargy and ascites in summer flounders''' is the typical presentation of ''C. bullocki'' infection. Mortality usually occurs within 11 weeks. Ascites and haemorrhaging in the '''ventral musculature''' often also occur around 5 weeks after infection. In acute infections, the parasite can be found extravascularly, often in adipose and haematopoietic tissues.
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| − | '''Necrotic foci''' form in the liver and diffuse splenic necrosis is also seen. '''Ulcers''' may be found in the abdomen and oedema and haemorrhage is common in the gastrointestinal tract. Focal lesions and congestion in the glomeruli may also feature.
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| − | ==Diagnosis==
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| − | Clinical signs and pathology as discussed individually above can be used for preliminary diagnosis.
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| − | Parasites are easily demonstrated in '''wet mounts''' from tissue samples during the '''acute phase''' of disease. Fresh samples from gills, mucus, viscera or blood/ascitic fluid depending on the species implicated, can be examined under cover slips using '''bright field or phase contrast''' microscopy for moving flagellates. Smears can also be fixed in ethanol and stained with Giemsa for confirmation under light microscopy.
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| − | '''Clotting techniques and haematocrit centrifuge''' techniques are useful for detecting '''low level''' parasitaemia of haematozoic species, e.g. in early or chronic disease stages.
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| − | '''Antibodies''' can be detected sensitively by either '''microscopic immunosubstrate enzyme technique (MIDET) or [[Fluorescent antibody testing|Immunofluorescent Antibody Testing (IFAT)]]. [[ELISA testing|ELISA]]''' is also available for ''C. borreli'' in carp and ''C. salmositica'' in salmonid fish.
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| − | ==Treatment and Control==
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| − | '''Isometamidium chloride''' is effective against ''C. salmositica'' in Chinook salmon and can also be used prophylactically. It has also been used against other species.
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| − | A '''live vaccine''' is available which provides protection against ''C. salmositica'' for 2 years.
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| − | '''Selective breeding''' from resistant or asymptomatic breeds is also sensible.
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| − | {{Learning
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| − | |flashcards = [[Cryptobiosis Flashcards]]
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| − | }}
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| − | ==References==
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| − | <references/>
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| − | Woo, P. T. K (2001) '''Cryptobiosis and its control in North American fishes'''. ''International Journal for Parasitology'', 31(5/6):566-574.
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| − | Woo, P.T.K. (2006) '''Diplomonadida (Phylum Parabasalia) and Kinetoplastea (Phylum Euglenozoa)'''. In: '''Fish Diseases and Disorders Volume 1''': Protozoan and Metazoan Infections (ed. P.T.K. Woo), ''CABI'', Walingford, UK, pp. 46-115.
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| − | {{CABI source
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| − | |datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=87608&loadmodule=datasheet&page=2144&site=160 cryptobiosis] and [http://www.cabi.org/ahpc/Default.aspx?site=160&page=2144&LoadModule=datasheet&CompID=3&dsID=102566 ''Cryptobia'']
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| − | |date =15 July 2011
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| − | }}
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| − | <br><br><br>
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| − | {{Patrick Woo
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| − | |date = 24 August 2011}}
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| − | {{OpenPages}}
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| − | [[Category:Fish Diseases]]
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| − | [[Category:CABI Expert Review Completed]][[Category:CABI AHPC Pages]]
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