Changes

{{Taxobox

{{Taxobox

|name              = ''Aphanomyces invadans''

|name              = ''Aphanomyces invadans''

|species            = ''A. invadans''

|species            = ''A. invadans''

}}

}}

Also Known As – '''''EUS - Mycotic granulomatoses – MG - Red spot disease - RSD'''''

Caused By: '''''Aphanomyces invadans'''''  — also known as: '''''Aphanomyces invaderis — A. piscicida — EUS related Aphanomyces — ERA''

 

Caused By – ''Aphanomyces invadans – Also Known As – Aphanomyces invaderis – A. piscicida – EUS related Aphanomyces - ERA''

==Introduction==

==Introduction==

==Distribution==

==Distribution==

Disease is present in parts of the '''Asia-Pacific region and Australia'''.

Disease is present in parts of the '''Asia-Pacific region and Australia'''. A similar disease has also been reported in the eastern USA.

==Signalment==

==Signalment==

Over '''100 species''' have been confirmed to be affected by EUS.

Over '''100 species''' have been confirmed to be affected by EUS.

EUS occurs commonly during periods of '''low temperature and heavy rainfall'''.<ref>Bondad-Reantaso, M. G., Lumanlan, S. C., Natividad, J. M., Phillips, M. J (1992) '''Environmental monitoring of the epizootic ulcerative syndrome (EUS) in fish from Munoz, Nueva Ecija in the Philippines'''. In: Shariff, M., Subasinghe, R. P, Arthur, J. R. eds. '''Diseases in Asian Aquaculture 1'''. ''Manila, The Philippines: Fish Health Section, Asian Fisheries Society'', 475-490</ref> These conditions favour sporulation<ref>Lumanlan-Mayo, S. C., Callinan, R. B., Paclibare, J. O., Catap, E. S., Fraser, G. C (1997) '''Epizootic ulcerative syndrome (EUS) in rice-fish culture systems: an overview of field experiments 1993-1995'''. In: Flegel, T. W., MacRae, I. H. eds. '''Diseases in Asian Aquaculture III'''. ''Manila, The Philippines: Fish Health Section, Asian Fisheries Society'', 129–138</ref> and cold temperatures '''delay the inflammatory response''' of the fish to infection.<ref>Catap, E. S., Munday, B. L (1998) '''Effects of variations of water temperature and dietary lipids on the expression of experimental epizootic ulcerative syndrome (EUS) in sand whiting, Sillago ciliata. Gyobyo Kenkyu.''' Fish Pathology, 33(4):327-335</ref>

EUS occurs commonly during periods of '''low temperature and heavy rainfall in tropical and sub-tropical waters'''.<ref>Bondad-Reantaso, M. G., Lumanlan, S. C., Natividad, J. M., Phillips, M. J (1992) '''Environmental monitoring of the epizootic ulcerative syndrome (EUS) in fish from Munoz, Nueva Ecija in the Philippines'''. In: Shariff, M., Subasinghe, R. P, Arthur, J. R. eds. '''Diseases in Asian Aquaculture 1'''. ''Manila, The Philippines: Fish Health Section, Asian Fisheries Society'', 475-490</ref> These conditions favour sporulation<ref>Lumanlan-Mayo, S. C., Callinan, R. B., Paclibare, J. O., Catap, E. S., Fraser, G. C (1997) '''Epizootic ulcerative syndrome (EUS) in rice-fish culture systems: an overview of field experiments 1993-1995'''. In: Flegel, T. W., MacRae, I. H. eds. '''Diseases in Asian Aquaculture III'''. ''Manila, The Philippines: Fish Health Section, Asian Fisheries Society'', 129–138</ref> and cold temperatures '''delay the inflammatory response''' of the fish to infection.<ref>Catap, E. S., Munday, B. L (1998) '''Effects of variations of water temperature and dietary lipids on the expression of experimental epizootic ulcerative syndrome (EUS) in sand whiting, Sillago ciliata. Gyobyo Kenkyu.''' ''Fish Pathology'', 33(4):327-335</ref>

Some species have been shown to be resistant including Chinese carps, milkfish and tilapia.

Some species have been shown to be resistant including Chinese carps, milkfish and tilapia.

In early disease, '''red spots or small haemorrhagic lesions''' are found on the surface of the fish.  

In early disease, '''red spots or small haemorrhagic lesions''' are found on the surface of the fish.  

These progress to '''ulcers and eventually large necrotic erosions'''. Fungal '''mycelium''' is often visible on the top of the ulcers.

These progress to '''ulcers and eventually large necrotic erosions'''. Fungal '''mycelium''' is often visible on the surface of ulcers.

'''Death''' then follows rapidly due to '''visceral granulomata''', septicaemia and failure of osmoregulatory balance.

'''Death''' then follows rapidly due to '''visceral granulomata''', septicaemia and failure of osmoregulatory balance.

==Diagnosis==

==Diagnosis==

Positive diagnosis is made by '''analysis of histological sections demonstrating mycotic granulomas and isolation of the caudal fungus.'''

Positive diagnosis is made by '''analysis of histological sections demonstrating mycotic granulomas and isolation of the causal fungus.'''

Histology of early lesions reveals  '''acute spongiosis and epithelial cell loss'''. Degenerative changes progress through the '''dermis with hyperaemia, haemorrhages and inflammatory infiltration'''. In advanced stages, '''sarcolysis''' is also obvious. Fungal hyphae are enclosed by a '''well defined epithelioid cell layer''' and mycotic granulation spreads through the infected muscle and internal organs. '''Muscle fibres eventually disappear altogether and are replaced by fibrosis, inflammatory cells and new blood vessels'''.<ref>Chinabut, S., Roberts, R. J (1999) '''Pathology and Histopathology of Epizootic Ulcerative Syndrome (EUS)'''. ''Bangkok, Thailand: Aquatic Animal Health Research Institute, Department of Fisheries, Royal Thai Government'', pp 33</ref> These distinct features of EUS ulcers make histological analysis enough for a definitive diagnosis.

Histology of early lesions reveals  '''acute spongiosis and epithelial cell loss'''. Degenerative changes progress through the '''dermis with hyperaemia, haemorrhages and inflammatory infiltration'''. In advanced stages, '''sarcolysis''' is also obvious. Fungal hyphae are enclosed by a '''well defined epithelioid cell layer''' and mycotic granulation spreads through the infected muscle and internal organs. '''Muscle fibres eventually disappear altogether and are replaced by fibrosis, inflammatory cells and new blood vessels'''.<ref>Chinabut, S., Roberts, R. J (1999) '''Pathology and Histopathology of Epizootic Ulcerative Syndrome (EUS)'''. ''Bangkok, Thailand: Aquatic Animal Health Research Institute, Department of Fisheries, Royal Thai Government'', pp 33</ref> These distinct features of EUS ulcers make histological analysis enough for a definitive diagnosis.

'''Squash preparations''' of skeletal muscle from beneath an ulcer will also demonstrate septate fungal hyphae for a rapid provisional diagnosis.

'''Squash preparations''' of skeletal muscle from beneath an ulcer will also demonstrate septate fungal hyphae for a rapid provisional diagnosis.

Moderate, pale, raised lesions are best for '''fungal isolation'''. Muscle should be exposed '''sterilely''' by removing scales and searing the skin with a red hot spatula before dissecting with a sterile scalpel. 2mm samples should be placed in a petri dish containing '''Czapex Dox agar wih penicillin G and oxolinic acid'''. They should be incubated at room temperature and examined daily so that emerging hyphal tips can be transferred onto fresh plates to produce contaminant free cultures.

Moderate, pale, raised lesions are best for '''fungal isolation'''. Muscle should be exposed in a sterile manner by removing scales and searing the skin with a red hot spatula before dissecting with a sterile scalpel. 2mm samples should be placed in a petri dish containing '''Czapex Dox agar with penicillin G and oxolinic acid'''. They should be incubated at room temperature and examined daily so that emerging hyphal tips can be transferred onto fresh plates to produce contaminant free cultures.

   

   

The fungus can then be identified by '''inducing sporogenesis and demonstrating its typical asexual characteristics'''.<ref>Lilley, J. H., Callinan, R. B., Chinabut, S., Kanchanakhan, S., MacRae, I. H., Phillips, M. J (1998) '''Epizootic ulcerative syndrome (EUS) technical handbook'''. ''Bangkok, Thailand: Aquatic Animal Health Research Institute''</ref>

The fungus can then be identified by '''inducing sporogenesis and demonstrating its typical asexual characteristics'''.<ref>Lilley, J. H., Callinan, R. B., Chinabut, S., Kanchanakhan, S., MacRae, I. H., Phillips, M. J (1998) '''Epizootic ulcerative syndrome (EUS) technical handbook'''. ''Bangkok, Thailand: Aquatic Animal Health Research Institute''</ref>

==Treatment==

==Treatment==

Keeping diseased fish in '''good quality, clean water''' may allow recovery, but only if lesions are not too advanced and '''dark scars''' are often left behind.

Keeping diseased fish in '''good quality, clean water''' may allow recovery, but only if lesions are not too extensive and '''dark scars''' are often left behind on healing.

There is '''no effective treatment for advanced disease'''.

There is '''no effective treatment for advanced disease'''.

==References==

==References==

<references/>

<references/>

Animal Health & Production Compendium, '''Epizootic Ulcerative Syndrome datasheet''', accessed 13/07/2011 @ http://www.cabi.org/ahpc/

Bruno, D.W., van West, P. and Beakes, G.W. 2011. '''Saprolegnia and Other Oomycetes'''. 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. 669-720.

|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=83971&loadmodule=datasheet&page=2144&site=160 epizootic ulcerative syndrome] and [http://www.cabi.org/ahpc/Default.aspx?site=160&page=2144&LoadModule=datasheet&CompID=3&dsID=93178 ''Aphanomyces invadans'']

 

 

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