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[[Category:To Do - Jaimie Meagor]]
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{{Podcasts
|link = https://bloomsbury.mediacore.tv/podcasts/wikivet-english/edwardsiella-tarda
}}
{{Taxobox
|name =''Edwardsiella tarda''
|kingdom =[[:Category:Bacteria|Bacteria]]
|sub-kingdom =
|phylum = Proteobacteria
|super-class =
|class = Gammaproteobacteria
|sub-class =
|super-order =
|order = Enterobacteriales
|sub-order =
|super-family =
|family = [[Enterobacteriaceae]]
|sub-family =
|genus = Edwardsiella
|species = Edwardsiella tarda''
}}
Also known as: ''''' Edwardsiella septicaemia — ES — Edwardsiella tarda infection '''''— '''''Edwardsiellosis'''''— ''''' Emphysematous putrefactive disease of catfish '''''— ''''' Fish gangrene'''''— ''''' Red disease in eels'''''.
==Introduction==
''Edwardsiella tarda'' belongs to the '''[[Enterobacteriaceae]]''' family and is a '''motile Gram negative, small, straight rod with peritrichous flagella''' and measures 1 × 2-3mm. It is '''cytochrome oxidase negative''', and '''ferments glucose''' and is classified as '''facultatively anaerobic'''.
''Edwardsiella tarda'' infects '''freshwater and marine fishes, reptiles and amphibians and mammals throughout the world'''. It causes '''''Edwardsiella septicemia (ES)''''' which is also known as '''''fish gangrene, emphysematous putrefactive disease of catfish or red disease in eels'''''. It causes serious systemic infection in cultured channel fish in the USA and in eels and flounders in Japan. '''Pale skin, petechiation and necrotic abscesses within the muscle of fish (that have a putrid odour when incised) are characteristic of ES'''. Mortality rates can depend on the amount of stress that the fish are kept under and high temperature, poor water quality and high organic fertility probably contribute to the onset and severity of the disease.
Unlike ''E. ictaluri'', '''''E. tarda'' is zoonotic''' and can infect humans. [[Edwardsiella ictaluri|'''''E. ictaluri''''']] causes '''''enteric septicaemia of catfish (ESC)''''' and '''only infects fish species''', whereas '''''Edwardsiella hoshinae'' infects birds and reptiles'''.
==Signalment==
'''Wild hosts''' include European and Japanese eels, largemouth bass, striped sea bass, Atlantic salmon, Marble goby, snakes and birds.
'''Domestic hosts''' include '''Japanese Eels, channel catfish''', Siamese fighting fish, carp species including catla and rosy barb, crimson and European seabass, black tetra, Asian seabass (barramundi), rainbow trout, chinook salmon, Nile tilapia, red seabream, turbot, and Angel fish.
Other fish hosts that have been documented are perch-like species including Cichlidae, Chrysophrys unicolor, flathead mullet , bastard halibut, flounders, and mozambique tilapia. '''''E. tarda'' can also be found in zoo animals, zebu, cattle, pigs, reptiles, marine mammals, members of the Alligatoridae family (alligators and caimans) and humans.'''
==Clinical Signs==
Clinical signs vary between fish species; consequently they are generally of little use except to indicate a bacterial infection.
All life stages of fish are affected by ''E. tarda'' and '''haemorrhaging of the body cavity, muscle, and organs including liver and kidneys''' are commonly seen. Within the '''kidneys and spleen''', necrotic '''white/grey lesions''' can be seen on the surface of the organs.
In adult fish, a variety of clinical sign can be seen including '''organomegaly, pale inflamed gills, exophthalmia and cataracts, haemorrhagic red lesions (ecchymosis) on the skin and fins, erosion of the skin, systemic oedema and ascites'''. The anal region of certain species can become swollen and hyperaemic and '''rectal prolapses''' can occur.
General '''behavioural changes''' include '''loss of balance, bursts of abnormal activity, and increased food consumption'''.
'''In humans''' it causes '''diarrhoea, gastroenteritis''', while extraintestinal infections may produce '''typhoid-like illness, peritonitis with sepsis, cellulitis and meningitis'''.
==Epidemiology==
''E.tarda'' commonly resides in the '''intestine of fish and other aquatic animals''' and in the bottom '''mud''' of many bodies of water. Within the USA, ''E.tarda'' has been '''isolated from the mud, water samples, frogs, turtles and crayfish from catfish ponds'''. The bacteria are transmitted through infected water and mud from '''carrier animal faeces''', and most probably infect susceptible fish through trauma of the epithelium or via the intestines. The infection can be enhanced by water temperatures of 20-30°C.
Humans have been known to be infected with ''E. tarda'' by '''eating infected fish meat'''.
==Distribution==
''E.tarda'' is a ubiquitous organism and is predominantly found in fish cultured in the '''USA, Venezuela, Japan, Taiwan, Korea, India, Thailand, Egypt, Israel and many developing countries''' including '''Africa and South and Central America'''. It has also been found in wild fish from '''Canada, USA and Australia'''.
==Pathology==
Histopathology shows suppurative interstitial '''nephritis in adult eels''', with masses of degenerate neutrophils containing bacteria. Within early stages of infection small abscesses are present. These enlarge and liquefy, spreading bacteria to surrounding tissues and vessels, causing '''ulceration of the dermis and emboli''' and infecting the spleen, liver, epicardium, stomach, gill and musculature.
In the '''hepatitis form, micro-abscesses can also develop in the liver''' and in different species, such as Japanese flounders, red sea bream, Japanese eels and tilapia, show predominantly '''granulomatous inflammation'''.
At least some ''E. tarda'' isolates produce '''toxic extracellular products (ECP)''' which may play a role in their virulence. Its '''haemolytic activity''', which is partially '''regulated by iron concentration''', could contribute to the pathogenicity of this bacteria to humans.
==Diagnosis==
''E. tarda'' can be '''isolated on brain–heart infusion (BHI) agar''' or '''trypton soya agar (TSA)''' with inocula from infected internal organs or muscle. It forms '''small, round, convex transparent colonies''' (0.5 mm in diameter) after 24-48 hours. On '''''Edwardsiella'' isolation media (EIM)''', it forms '''small green colonies with black centres'''.
'''Indirect [[FAT]] (detecting antibodies) and enzyme-linked immunosorbent assay ([[ELISA testing|ELISA]]) test ''' is used to confirm the presence of ''E. tarda''. There is no serological cross-reactivity between ''E. tarda'' and ''E. ictaluri''. More recently, a '''loop-mediated isothermal amplification (LAMP)''' for rapid and sensitive detection of ''E. tarda'' has been developed <ref name="Savan et al, 2004">Savan, R., Igarashi, A., Matsuoka, S., Sakai, M., (2004) '''Sensitive and rapid detection of edwardsiellosis in fish by a loop-mediated isothermal amplification method'''. ''Applied and Environmental Microbiology'', 70(1):621-624.</ref>.
==Treatment==
'''Oxytetracycline, sulfadimethoxine or methoprim''' have been used to treat ES. The '''latter two can cause cessation of feeding''' in some fish species.
Antibiotic resistant strains have been isolated e.g. in Taiwan. Some of these resistant strains can be treated with the addition of '''oxalinic acid''' or '''miloxacin''' in their feed.
==Control==
ES may be controlled by the '''immersion of fish in formalin-killed whole cells (FKC), lipopolysaccharide (LPS) culture filtrates or whole cell bacterins vaccines'''. The two former vaccination may be administered via intramuscular injection and can cause death to some fish species.
{{Learning
|flashcards = [[Edwardsiella tarda Flashcards|''Edwardsiella tarda'' Flashcards]]
}}
==References==
<references/>
Evans, J., Klesius, P.H., Plumb, J.A. , Shoemaker, C.A. (2011). '''Edwardsiella Septicaemias.''' In: '''Fish Diseases and Disorders, Volume 3''', 2nd edition (eds. P.T.K. Woo and D.W. Bruno), ''CABI'', Wallingford, UK. pp. 512-569.
{{CABI source
|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=84399&loadmodule=datasheet&page=2144&site=160 ''Edwardsiella tarda''] and [http://www.cabi.org/ahpc/Default.aspx?site=160&page=2144&LoadModule=datasheet&CompID=3&dsID=84398 Edwardsiella septicaemia (Edwardsiella tarda infection)]
|date =10 July 2011
}}
<br><br>
{{Patrick Woo
|date = 15 September 2011
}}
{{OpenPages}}
[[Category:Zoonoses]]
[[Category:Fish Diseases]]
[[Category:Enterobacteriaceae]]
[[Category:CABI Expert Review Completed]][[Category:CABI AHPC Pages]]