Changes

{{Taxobox

{{Taxobox

|name              = ''Yersinia ruckeri''

|name              = ''Yersinia ruckeri''

|sub-order          =

|sub-order          =

|super-family      =

|super-family      =

|family            = Enterobacteriaceae

|family            = [[:Category:Enterobacteriaceae|Enterobacteriaceae]]

|sub-family        =

|sub-family        =

|genus              = Yersinia

|genus              = [[:Category:Yersinia species|Yersinia]]

|species            = ''Y. ruckeri''

|species            = ''Y. ruckeri''

}}

}}

Also Known As – '''''ERM – Redmouth – Redthroat - Yersiniosis'''''

Caused By: '''''Yersinia ruckeri''

 

Caused By – ''Yersinia ruckeri''

==Introduction==

==Introduction==

'''Enteric redmouth disease''' is a disease of fish caused by the '''gram negative, rod shaped, slightly curved [[Bacteria|bacterium]]''', '''''Yersinia ruckeri'''''. Most of the bacteria are '''motile''' due to their having '''seven or eight flagellae''', although they only function at temperatures above 9⁰C and below 35⁰C .  

'''Enteric redmouth disease''' is a disease of fish caused by the '''gram negative, rod shaped, slightly curved [[Bacteria|bacterium]]''', '''''Yersinia ruckeri'''''. Most of the bacteria are '''motile''' due to having '''seven or eight flagellae''', although they only function at temperatures above 9⁰C and below 35⁰C .  

There are six known serovars of ''Y. Ruckeri''. Many fish species involve a '''carrier state''' and are only detected when '''stressed''', becoming a significant source of disease.

There are six known serovars of ''Y. ruckeri''. Many fish species involve a '''carrier state''' and are only detected when '''stressed''', becoming a significant source of disease.

ERM can be '''acute or chronic'''. Economic losses due to the disease can be significant.

ERM can be '''acute or chronic'''. Economic losses due to the disease can be significant.

==Distribution==

==Distribution==

Europe, North and South America and Australia.

Europe, North and South America, Africa, Asia and Australia.

ERM can be '''transmitted via water''' and it is poorly understood whether this is due to saprophytic function or merely prolonged survival in the presence of sediment and organic matter facilitating transmission and infection.<ref>Romalde, J. L., Barja, J. L., Magarinos, B., Toranzo, A. E (1994) '''Starvation-survival processes of the bacterial fish pathogen Yersinia ruckeri'''. Systematic and Applied Microbiology, 17:161-168</ref> The bacterium is '''shed in the faeces''' of infected fish and the quantity '''increases exponentially with stress'''. Once infected, a population can maintain the disease indefinitely.

ERM can be '''transmitted via water''' and it is poorly understood whether this is due to saprophytic function or merely prolonged survival in the presence of sediment and organic matter facilitating transmission and infection.<ref>Romalde, J. L., Barja, J. L., Magarinos, B., Toranzo, A. E (1994) '''Starvation-survival processes of the bacterial fish pathogen ''Yersinia ruckeri'''''. ''Systematic and Applied Microbiology'', 17:161-168</ref> The bacterium is '''shed in the faeces''' of infected fish and the quantity '''increases exponentially with stress'''. Once infected, a population can maintain the disease indefinitely.

==Signalment==

==Signalment==

The disease is primarily of '''cultured salmonid fish''' but a number of other fish families have been found to be infected leading to the belief that its '''host range is quite diverse'''.

The disease is primarily of '''cultured salmonid fish''' but a number of other fish families have been found to be infected leading to the belief that its '''host range is quite diverse'''.

Young fish '''1-5months old''' are more susceptible to ERM than adults and '''brook trout''' appear to be most vulnerable.<ref> Good, C. M., Thorburn, M. A., Stevenson, R. M. W (2001) '''Host factors associated with the detection of Aeromonas salmonicida and Yersinia ruckeri in Ontario, Canada government fish hatcheries'''. Preventive Veterinary Medicine, 49(3/4):165-173</ref>

Young fish '''1-5 months old''' are more susceptible to ERM than adults and '''brook trout''' appear to be most vulnerable.<ref> Good, C. M., Thorburn, M. A., Stevenson, R. M. W (2001) '''Host factors associated with the detection of ''Aeromonas salmonicida'' and ''Yersinia ruckeri'' in Ontario, Canada government fish hatcheries'''. ''Preventive Veterinary Medicine'', 49(3/4):165-173</ref>

Infections have not been reported below 10⁰C.

Infections have not been reported below 10⁰C.

The '''reddening of the throat and mouth''' that give the disease its name are caused by '''subcutaneous haemorrhage''' and are common but not always present. This can progress to '''erosion of the jaw and palate if untreated'''.

The '''reddening of the throat and mouth''' that give the disease its name are caused by '''subcutaneous haemorrhage''' and are common but not always present. This can progress to '''erosion of the jaw and palate if untreated'''.

Affected fish also have generally '''darkened skin and fins''' with haemorrhagic lesions around the '''gill tips, vent and fins and are lethargic and inappetant'''. They may have a '''distended abdomen''' leading to a “pot-bellied” appearance. Fish are often pale around the gills and may demonstrate '''exopthalmos''' with periorbital oedema. They may be seen to be swimming close to the surface.

Affected fish also have generally '''darkened skin and fins''' with haemorrhagic lesions around the '''gill tips, vent and fins and are lethargic and inappetant'''. They may have a '''distended abdomen''' leading to a “pot-bellied” appearance. Fish are often pale around the gills and may demonstrate [[Exopthalmos - Fish|'''exopthalmos''']] with periorbital oedema. They are anorexic and may swim close to the surface.

'''Mortalities are frequent and variable. They may occur in small fry with virtually no preceding signs'''.<ref>Kawula, T. H., Lelivelt, M. J., Orndorff, P. E (1996) '''Using a new inbred fish model and cultured fish tissue cells to study Aeromonas hydrophila and Yersinia ruckeri pathogenesis'''. Microbial Pathogenesis, 20(2):119-125; 12</ref> Losses of 15% over a cycle are not uncommon and can reach 90% on small scale units.

'''Mortalities are frequent and variable. They may occur in small fry with virtually no preceding signs'''.<ref>Kawula, T. H., Lelivelt, M. J., Orndorff, P. E (1996) '''Using a new inbred fish model and cultured fish tissue cells to study '''Aeromonas hydrophila''' and '''Yersinia ruckeri''' pathogenesis'''. ''Microbial Pathogenesis'', 20(2):119-125; 12</ref> Losses of 15% over a cycle are not uncommon and can reach 90% on small scale units.

==Diagnosis==

==Diagnosis==

Diagnosis is often presumed from '''history at a site and clinical signs but these are not specific''' and represent many other gram negative septicaemic diseases.   

Diagnosis is often presumed from '''history at a site and clinical signs but these are not specific''' and represent many other gram negative septicaemic diseases.   

Confirmation is most easily made by '''culture from tissue samples of the spleen, heart and kidney'''. Media such as '''tryptone soya''' are widely available and very effective. They can be supplemented with 5% blood to increase success. The bacterium can then be '''serologically diagnosed by traditional methods, monoclonal or polyclonal antibody testing and antigen [[ELISA testing|ELISA]]'''.

Confirmation is most easily made by '''culture from tissue samples of the spleen, heart and kidney'''. Media, such as '''tryptone soya''', are widely available and very effective. They can be supplemented with 5% blood to increase success. The bacterium can then be '''serologically diagnosed by traditional methods, monoclonal or polyclonal antibody testing and antigen [[ELISA testing|ELISA]]'''.

'''Antibodies''' to ERM can be detected using '''[[Agglutination|Latex Agglutination]]''' and can also detect subclinical infections.<ref>Romalde, J. L., Magarinos, B., Fouz, B., Bandín, I., Núnez, S., Toranzo, A. E (1995) '''Evaluation of BIONOR mono-kits for rapid detection of bacterial fish pathogens'''. Diseases of Aquatic Organisms, 21(1):25-34; 32</ref>

'''Antibodies''' to ERM can be detected using '''[[Agglutination|latex agglutination]]''' and can also detect subclinical infections.<ref>Romalde, J. L., Magarinos, B., Fouz, B., Bandín, I., Núnez, S., Toranzo, A. E (1995) '''Evaluation of BIONOR mono-kits for rapid detection of bacterial fish pathogens'''. ''Diseases of Aquatic Organisms'', 21(1):25-34; 32</ref>

The most recent method is '''PCR''' and is capable of detecting very low levels of Y. Ruckeri but is insensitive and not commercially available.

The most recent method is '''PCR''' and is capable of detecting very low levels of ''Y. ruckeri'' but is insensitive and not commercially available. It is recommended that identification of pure cultures be based on amplification and sequencing of the 16S rRNA gene using universal bacterial primers 27F and 1492R.

At '''necropsy''', there is '''congestion of blood vessels''' throughout the peritoneum and white-grey patches of necrosis and '''petechial haemorrhages''' are found in the liver, swim bladder, pancreas, lateral muscles and adipose tissue. '''Serosanguinous fluid often accumulates''' in the body cavities and muscle which become yellow and mucoid within the intestinal tract. There may also be severe damage of the haematopoietic renal tissues.

At '''necropsy''', there is '''congestion of blood vessels''' throughout the peritoneum and white-grey patches of necrosis and '''petechial haemorrhages''' are found in the liver, swim bladder, pancreas, lateral muscles and adipose tissue. '''Serosanguinous fluid often accumulates''' in the body cavities and muscle which become yellow and mucoid within the intestinal tract. There may also be severe damage of the haematopoietic renal tissues.

'''Acute anaemia with a haematocrit as low as 23%''' has also been noted<ref>Lehman, J., Sturenberg, F. J., Mock, D (1987) '''The changes in haemogram of rainbow trout (Salmo gairdneri, Richardson) to an artificial and natural challenge with Yersinia ruckeri'''. Journal of Applied Ichthyology, 3:174-183 </ref> and is thought to be due to '''endotoxic effects'''.<ref> Miller, T (1983) '''Blood coagulation in ERM infected trout: role of bacterial endotoxin'''. In: Proceedings of the 8th Annual FHS/AFS Workshop, ''Kearneysville, West Virginia, USA'',48</ref>

'''Acute anaemia with a haematocrit as low as 23%''' has also been noted<ref>Lehman, J., Sturenberg, F. J., Mock, D (1987) '''The changes in haemogram of rainbow trout (''Salmo gairdneri'', Richardson) to an artificial and natural challenge with ''Yersinia ruckeri'''''. ''Journal of Applied Ichthyology'', 3:174-183 </ref> and is thought to be due to '''endotoxic effects'''.<ref> Miller, T (1983) '''Blood coagulation in ERM infected trout: role of bacterial endotoxin'''. In: Proceedings of the 8th Annual FHS/AFS Workshop, ''Kearneysville, West Virginia, USA'',48</ref>

==Treatment==

==Treatment==

ERM responds well to '''antibiotic treatment with oxolinic acid, oxytetracycline, sulphamerazine and tribrissen'''.  

ERM responds well to '''antibiotic treatment with oxolinic acid, oxytetracycline, sulphamerazine and tribrissen'''. '''Amoxicillin''' is now licenced for use in the UK.

'''Vaccines''' can also be used as treatments for infected fish.

'''Vaccines''' can also be used as treatments for infected fish.

'''Good husbandry and water quality are key to minimising the stress''' that precipitates disease.

'''Good husbandry and water quality are key to minimising the stress''' that precipitates disease.

'''Two very effective vaccines''' are also available but may not provide comprehensive cross-protection in all situations.<ref> Erdal, J. I (1989) '''Vaccination against common infectious disease of fish'''. Norsk Veterinærtidsskrift, 101(6):489-495; 4</ref>

'''Two very effective vaccines''' are also available but may not provide comprehensive cross-protection in all situations.<ref> Erdal, J. I (1989) '''Vaccination against common infectious disease of fish'''. ''Norsk Veterinærtidsskrift'', 101(6):489-495; 4</ref>

{{Learning

{{Learning

==References==

==References==

<references/>

<references/>

Animal Health & Production Compendium, '''Enteric Redmouth Disease datasheet''', accessed 13/07/2011 @ http://www.cabi.org/ahpc/

Barnes, A.C. 2011. '''Enteric Redmouth Disease (ERM) (Yersinia ruckeri)'''. In: '''Fish Diseases and Disorders Volume 3''': Viral, Bacterial and Fungal Infections (eds. P.T.K. Woo and D.W. Bruno), ''CABI'', Walingford, UK, pp. 484-511.

|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=83811&loadmodule=datasheet&page=2144&site=160 enteric redmouth disease] and [http://www.cabi.org/ahpc/Default.aspx?site=160&page=2144&LoadModule=datasheet&CompID=3&dsID=59813 ''Yersinia ruckeri'']

 

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