Changes

|kingdom            = Protista

|kingdom            = Protista

|sub-kingdom        =

|sub-kingdom        =

|phylum            = Protozoa

|phylum            = [[:Category:Protozoa|Protozoa]]

|super-class        = Sarcomastigophora

|super-class        = Sarcomastigophora

|class              =

|class              =

|species            =

|species            =

}}

}}

 

Caused By: '''''Cryptobia branchialis — C. iubilans — C. salmositica — C. bullocki — C. borreli''

Caused By – ''Cryptobia branchialis= C. iubilans – C. salmositica – C. bullocki – C. borreli''

==Introduction==

==Introduction==

Cryptobia species are '''bi-flagellated [[Protozoa|protozoan]] pathogens''' that infect a range of vertebrate and invertebrate hosts but 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'''. Blood parasites have ectoparasitic life stages on the external body surface.

Cryptobia species are '''bi-flagellated [[Protozoa|protozoan]] pathogens''' that infect a range of vertebrate and invertebrate hosts but 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'''. Blood parasites have ectoparasitic life stages on the external body surface.

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>

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>

==Distribution==

==Distribution==

''C. bullocki'' is isolated in marine fish in the '''USA and Northern Gulf of Mexico'''.

''C. bullocki'' is isolated in marine fish in the '''USA and Northern Gulf of Mexico'''.

''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 excreted in '''mucus'''. ''C salmositica'' has been diagnosed where no leeches were found so is more 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>. 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 fish are separated by wire screens.

''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 excreted in '''mucus'''. ''C. salmositica'' has been diagnosed where no leeches were found so is more 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>. 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 fish are separated by wire screens.

==Signalment==

==Signalment==

''C. bullocki'' causes disease and mortality in '''marine''' fish. ''C. salmositica'' has also been found on fish in sea water. The rest of the pathogenic species are '''usually parasitic to freshwater species'''.

''C. bullocki'' causes disease and mortality in '''marine''' fish. ''C. salmositica'' has also been found on fish in sea water. The rest of the pathogenic species are '''usually parasitic to freshwater species'''.

Leech numbers increase in '''November''' and so prevalence and severity of parasitaemia are higher in haematozoic infections during the northern hemisphere Winter.<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>

Leech numbers increase in '''November''' and so prevalence and severity of parasitaemia are higher in haematozoic infections during the northern hemisphere Winter.<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>

==Clinical Signs and Pathology==

==Clinical Signs and Pathology==

=== ''C. branchialis'' – Respiratory Ectoparasite ===

=== ''C. branchialis'' – Respiratory Ectoparasite ===

'''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.

'''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.

=== ''C. iubilans'' – Gastrointestinal Endoparasite ===

=== ''C. iubilans'' – Gastrointestinal Endoparasite ===

=== ''C. salmositica'' – Haematozoic Endoparasite ===

=== ''C. salmositica'' – Haematozoic Endoparasite ===

'''Exophthalmia, splenomegaly, hepatomegaly, oedema, ascites, [[Anaemia|anaemia]] and marked emaciation''' are signs of infection with the blood-borne ''C. salmositica''. [[Anaemia|anaemia]] is usually '''microcytic and hypochromic''', caused by '''haemolytic action of parasitic secretions (haemolysin)''' 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.

'''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)''' 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.

Infected fish are also '''more sensitive to environmental hypoxia''' due to 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>

Infected fish are also '''more sensitive to environmental hypoxia''' due to 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>

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.'''

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.'''

=== ''C. borreli'' – Haematozoic Endoparasite ===

=== ''C. borreli'' – Haematozoic Endoparasite ===

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.

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.

=== ''C. bullocki'' - Haematozoic Endoparasite ===

=== ''C. bullocki'' - Haematozoic Endoparasite ===

==Treatment and Control==

==Treatment and Control==

'''Isometamidium chloride''' is effective against ''C. salmositica'' in Chinook salmon and can also be used prophylactically. it has also been used against other species.

'''Isometamidium chloride''' is effective against ''C. salmositica'' in Chinook salmon and can also be used prophylactically. It has also been used against other species.

A '''live vaccine''' is available which provides protection against ''C. bullocki'' and ''C. salmositica'' for 2 years.  

A '''live vaccine''' is available which provides protection against ''C. bullocki'' and ''C. salmositica'' for 2 years.  

Woo, P. T. K (2001) '''Cryptobiosis and its control in North American fishes'''. International Journal for Parasitology, 31(5/6):566-574.

Woo, P. T. K (2001) '''Cryptobiosis and its control in North American fishes'''. International Journal for Parasitology, 31(5/6):566-574.

[[Category:To Do - CABI review]]

 

[[Category:CABI Expert Review]]