Changes

|sub-order          =

|sub-order          =

|super-family      =

|super-family      =

|family            = Enterobacteriaceae

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

|sub-family        =

|sub-family        =

|genus              = Edwardsiella

|genus              = Edwardsiella

|species            = ''Edwardsiella ictaluri''

|species            = ''Edwardsiella ictaluri''

}}

}}

Also known as: ''''' Enteric septicaemia of catfish '''''—'''''Hole in the head disease'''''.

Also known as: ''''' Enteric Septicaemia of Catfish — Hole in the Head Disease — ESC'''''.

==Introduction==

==Introduction==

'''''Edwardsiella ictaluri''''' belongs to the '''''Enterobacteriaceae''''' family and is a '''Gram negative''', short, pleomorphic '''rod''', measuring 0.75 × 1.5-2.5 µm, which is '''weakly motile''' at 25-30°C, but not at higher temperatures. It has peritrichous flagella and occasionally pili that can be seen with a scanning electron micrographs and can have between one to three '''plasmids''' depending on their molecular mass. It is generally considered an '''obligate pathogen''', although it can survive in steralised pond bottom mud for over 90days but does not compete well with other microbes. The organism is '''lactose negative, catalase-positive, cytochrome oxidase-negative, glucose fermentative and reduces nitrate to nitrite'''.<ref name="Shotts and Teska, 1989">Shotts, E.B., Teska, J.D., (1989) '''Bacterial pathogens of aquatic vertebrates'''. In: Austin B, Austin DA, eds. ''Methods for the Microbiological Examination of Fish and Shellfish'''. Chichester, UK: Ellis Horwood, 164-186.</ref>.

'''''Edwardsiella ictaluri''''' belongs to the '''''[[Enterobacteriaceae]]''''' family and is a '''Gram negative''', short, pleomorphic '''rod''', measuring 0.75 × 1.5-2.5 µm, which is '''weakly motile''' at 25-30°C, but not at higher temperatures. It has peritrichous flagella and occasionally pili that can be seen with a scanning electron micrographs and can have between one to three '''plasmids''' depending on their molecular mass. It is generally considered an '''obligate pathogen''', although it can survive in sterilised pond bottom mud for over 90 days but does not compete well with other microbes. The organism is '''lactose negative, catalase-positive, cytochrome oxidase-negative, glucose fermentative and reduces nitrate to nitrite'''.<ref name="Shotts and Teska, 1989">Shotts, E.B., Teska, J.D., (1989) '''Bacterial pathogens of aquatic vertebrates'''. In: Austin B, Austin DA, eds. ''Methods for the Microbiological Examination of Fish and Shellfish'''. Chichester, UK: Ellis Horwood, 164-186.</ref>

''E. ictaluri'' '''affects fish species only''' and '''causes enteric septicaemia of catfish (ESC)''' and various other species of fish. ESC is considered one of the '''most important infectious disease''' problems in the '''commercial catfish industry''' in the '''USA'''. [[Edwardsiella tarda|'''''Edwardsiella.tarda''''']] causes '''Edwardsiella septicemia (ES)''' which is also known as '''fish gangrene, emphysematous putrefactive disease of catfish''' or '''red disease in eels''' and it '''can affect other animals'''.  Whereas '''''E. hoshinae'' infects birds and reptiles'''.  

''E. ictaluri'' '''affects fish species only''' and causes '''enteric septicaemia of catfish (ESC)''' and various other species of fish. ESC is considered one of the '''most important infectious disease''' problems in the '''commercial catfish industry''' in the '''USA'''. Other species of ''Edwardsiella'' include [[Edwardsiella tarda|'''''E. tarda''''']], which causes septicemia in fish and can affect other animals, whereas '''''E. hoshinae'' infects birds and reptiles'''.  

Within '''channel catfish''' species the bacteria causes '''two forms of ESC'''; an '''acute septicaemia''' and '''chronic encephalitis'''. In the latter form the infection spreads from the olfactory sacs, and migrates along the olfactory nerves to the brain, generating granulomatous inflammation. In the acute form of ESC the disease is thought to develop from the intestinal mucosa causing a bacteremia.  

Within '''channel catfish''' species the bacteria cause '''two forms of ESC'''; an '''acute septicaemia''' and '''chronic encephalitis'''. In the latter form the infection spreads from the olfactory sacs, and migrates along the olfactory nerves to the brain, generating granulomatous inflammation. In the acute form of ESC, the disease is thought to develop from the intestinal mucosa causing a bacteremia.  

==Signalment==

==Signalment==

[[File:Channel Catfish.jpg|thumb|200px|right|Channel Catfish]]

[[File:Channel Catfish.jpg|thumb|200px|right|Channel Catfish]]

With '''acute forms of ESC''' you can see '''petechial haemorrhages '''around the buccal area, throat, abdomen and the fin base, that progress to '''depigmented ulcers'''. Fish generally suffer from '''moderate pale inflamed gills, exophthalmia, anaemia, haemorrhagic enteritis, systemic oedema, dropsy, ascites and splenomegaly'''. General '''behavioural changes''' include loss of balance, swimming near the surface, lethargy and cessation of feeding.   

With the '''chronic form of ESC''' clinical signs include, '''altered mentation, listlessness''' and '''chaotic swimming with ‘head-up, tail-down’ posture, circling''' and '''mortality'''.  In later stages the '''dorsum of the head swells''' and '''ulcerates revealing areas of the brain''' (hence the name ‘hole in the head disease’).  With '''acute forms of ESC''' you can see '''petechial haemorrhages around the buccal area, throat, abdomen and the fin base, that progress to depigmented ulcers'''. Fish generally suffer from '''moderate pale inflamed gills, exophthalmia, anaemia, haemorrhagic enteritis, systemic oedema, dropsy, ascites and splenomegaly'''. General '''behavioural changes''' include '''loss of balance, swimming near the surface, lethargy and cessation of feeding'''.   

==Epidemiology==

==Epidemiology==

The  bacteria can survive in pond sediment and once a population of fish have recovered from an infection of ECS, they can become '''carriers'''. It can be found in the kidneys of fishes and is thought to be shed in the faeces of fish.  

The  bacteria can survive in pond sediment and once a population of fish have recovered from an infection of ECS, they can become '''carriers'''. They can be found in the kidneys of fishes and are thought to be shed in the faeces of fish.  

'''Outbreaks''' are mainly '''seasonal''' and '''occur within a set temperature range of  18-28°C''', primarily in spring and autumn.  This temperature limitation precludes the bacterium from being a pathogen for humans or other warm-blooded animals <ref name="Janda et al., 1991">Janda, J., Abbott, S.L., Kroske-Bystrom, S., Cheung, W.K., Powers, C., Koka, R.P., Tamura, K., (1991)  '''Pathogenic properties of Edwardsiella species'''. ''Journal of Clinical Microbiology'', 29:1997-2001.</ref> and is not therefore zoonotic. Other '''environmental factors''' have been '''linked to outbreaks''' and include '''poor water quality, high stocking density and other stressors'''.   

 

'''Outbreaks''' are mainly '''seasonal''' and occur within a set temperature range of  '''18-28°C''', primarily in spring and autumn.  This temperature limitation precludes the bacterium from being a pathogen for humans or other warm-blooded animals <ref name="Janda et al., 1991">Janda, J., Abbott, S.L., Kroske-Bystrom, S., Cheung, W.K., Powers, C., Koka, R.P., Tamura, K., (1991)  '''Pathogenic properties of Edwardsiella species'''. ''Journal of Clinical Microbiology'', 29:1997-2001.</ref> and is not therefore zoonotic. Other '''environmental factors''' have been linked to outbreaks and include poor water quality, high stocking density and other stressors.   

''E.ictaluri''  can '''invade the, gill mucosa, olfactory organ and nasal epithelium and nerve, brain meninges, skull and capillaries in the dermis of the skin'''.  

''E.ictaluri''  can '''invade the, gill mucosa, olfactory organ and nasal epithelium and nerve, brain meninges, skull and capillaries in the dermis of the skin'''.  

==Pathology==  

==Pathology==  

'''Histological examination''' reveals a '''systemic infection of all organs''' and '''skeletal muscles''', with the most severe changes being '''diffuse interstitial necrosis''' of the anterior and posterior '''kidney and systemic haemorrhages'''. '''Focal necrosis in the liver''' and '''spleen''' are also generally seen as '''pale grey/white lesions'''.  Skeletal muscle and areas of necrosis within internal organ tissue can be '''infiltrated with macrophages''', that phagocytose the bacteria but do not destroy it <ref name="Miyazaki and Plumb, 1985">Miyazaki, T., Plumb, J,A., (1985) '''Histopathology of Edwardsiella ictaluri in channel catfish, Ictalurus punctatus (Rafinesque)'''. ''Journal of Fish Diseases'', 8(4):389-392.(</ref>, <ref name="Klesius et al., 1991">Klesius, P., Johnson, K., Durborow, R., Vinitnantharat, S., (1991)  '''Development and evaluation of an enzyme-linked immunosorbent assay for catfish serum antibody to Edwardsiella ictaluri'''. ''Journal of Aquatic Animal Health'', 3(2):94-99.</ref>, <ref name="Klesius, 1993">Klesius, P.H., (1993)   '''Rapid enzyme-linked immunosorbent tests for detecting antibodies to Edwardsiella ictaluri in channel catfish, Ictalurus punctatus, using exoantigen'''. ''Veterinary Immunology and Immunopathology'', 36(4):359-368.</ref>.

'''Histological examination''' reveals a '''systemic infection of all organs''' and '''skeletal muscles''', with the most severe changes being '''diffuse interstitial necrosis''' of the anterior and posterior '''kidney and systemic haemorrhages'''. '''Focal necrosis in the liver''' and '''spleen''' are also generally seen as '''pale grey/white lesions'''.   

 

Skeletal muscle and areas of necrosis within internal organ tissue can be '''infiltrated with macrophages''', that phagocytose the bacteria but do not destroy them <ref name="Miyazaki and Plumb, 1985">Miyazaki, T., Plumb, J,A., (1985) '''Histopathology of Edwardsiella ictaluri in channel catfish, Ictalurus punctatus (Rafinesque)'''. ''Journal of Fish Diseases'', 8(4):389-392.(</ref>, <ref name="Klesius et al., 1991">Klesius, P., Johnson, K., Durborow, R., Vinitnantharat, S., (1991)  '''Development and evaluation of an enzyme-linked immunosorbent assay for catfish serum antibody to Edwardsiella ictaluri'''. ''Journal of Aquatic Animal Health'', 3(2):94-99.</ref>, <ref name="Klesius, 1993">Klesius, P.H., (1993) '''Rapid enzyme-linked immunosorbent tests for detecting antibodies to Edwardsiella ictaluri in channel catfish, Ictalurus punctatus, using exoantigen'''. ''Veterinary Immunology and Immunopathology'', 36(4):359-368.</ref>.

==Diagnosis==

==Diagnosis==

'''Clinical signs''' are quite '''pathognomonic for ESC''' but '''PCR''' is used to confirm the presence of ''E. ictaluri'' in blood and tissues but other methods have been used such as '''indirect FAT (detecting antibodies)''' and '''ELISA''' test.

'''Clinical signs''' are quite '''pathognomonic '''for ESC but '''PCR''' is used to confirm the presence of ''E. ictaluri'' in blood and tissues but other methods have been used such as '''indirect [[FAT]] (detecting antibodies)''' and [[ELISA testing|'''ELISA''' test]].

The organism is '''slow growing''' and '''forms small, translucent, greenish colonies on Edwardsiella isolation media (EIM)''', while inhibiting Gram-positive and most Gram-negative contaminating organisms. ''E. ictaluri'' can be separated from [[Edwardsiella tarda|''E.tarda'']] because it is '''indole-negative''' and '''does not produce H2S on triple sugar iron (TSI) agar'''.  

 

The organism is '''slow growing''' and '''forms small, translucent, greenish colonies on ''Edwardsiella'' isolation media (EIM)''', while inhibiting Gram-positive and most Gram-negative contaminating organisms. ''E. ictaluri'' can be separated from [[Edwardsiella tarda|''E.tarda'']] because it is '''indole-negative''' and '''does not produce H₂S on triple sugar iron (TSI) agar'''.  

==Treatment==

==Treatment==

[[Category:To Do - CABI review]]

[[Category:CABI Expert Review]]