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Infectious Bursal Disease (view source)

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{{Podcasts
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|link = https://bloomsbury.mediacore.tv/podcasts/wikivet-english/infectious-bursal-disease
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{{Taxobox
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|name              = Infectious Bursal Disease Virus (IBDV)
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|kingdom            =
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|sub-kingdom        =
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|phylum            =
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|super-class        =
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|class              =
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|order              =  RNA Viruses
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|sub-order          =
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|super-family      =
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|family            = Birnaviridae
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|sub-family        =
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|genus              = Avibirnavirus
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|species            =
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}}
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Also Known As: '''''Gumboro Disease''''' — '''''Infectious Avian Nephrosis''''' — '''''Infectious Bursitis'''''
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Caused By: '''''Infectious Bursal Disease Virus — IBD — IBDV'''''
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==Introduction==
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Infectious bursal disease is a '''highly contagious [[Viruses | viral]]''' disease of birds caused by an avibirnavirus.
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The virus can survive in a wide range of environmental conditions, remains viable from pH 2-12 and is inactivated only in 70⁰C for 30 minutes. It is also resistant to some disinfectants.
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IBDV can '''survive''' in poultry houses for '''122 days''' after removal of infected birds and in contaminated water or feed for 52 days.
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Of the two known serotypes of IBDV, only '''Serotype 1''' is pathogenic, causing bursal disease in '''chicks''' by '''selectively''' infecting the cells of the '''[[Bursa of Fabricius]]'''.
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==Signalment==
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IBDV can infect chickens, turkeys, ducks, geese and guineafowl but only '''chickens''' show clinical signs of disease.
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Lethal infection is usually seen in chicks '''3-6 weeks old''' due to IBDV being restricted to cells at a certain stage of development.
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==Distribution==
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The virus is present worldwide.
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The main route of transmission is '''faecal-oral''' and the virus is shed for up to 2 weeks post-infection in large amounts.
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The role of wild birds as a mechanical vector is poorly understood. IBDV can also be spread by the [[Nematodes |nematode]] parasite, ''Alphitobius diaperinus''.
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IBD is not thought to be zoonotic.
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==Clinical Signs==
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One of the main effects of IBDV infection is '''mortality'''. This can be in chicks at 3-6 weeks old or later on as a result of severe '''immunosuppression''' allowing other disease to proliferate, in particular, [[Escherichia coli |''E. coli'']] and gangrenous dermatitis.
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The virulence varies massively and so can disease severity. Initial outbreaks are usually the most severe and recurrent disease is milder with lower mortality.
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'''[[Diarrhoea]]''', recumbency, '''dehydration''', neurological signs and ruffling of the feathers form a typical presentation of IBDV.
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==Diagnosis==
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Acute disease is usually recognised in a flock by '''rapid onset, high morbidity''' ([[Diarrhoea |diarrhoea]]) with a spike in mortality and '''rapid recovery'''. Diagnosis is confirmed by post-mortem or laboratory testing.
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===Post-mortem===
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On '''post-mortem examination''', carcasses are '''dehydrated''', often with '''darkened pectoral muscles'''. Many '''petechiae''' may be present in the thigh and pectoral muscle masses.
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Mucus may also be present within the [[Avian Intestines - Anatomy & Physiology|intestines]]. In advanced disease, renal changes may be evident due to prolonged dehydration.
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Grey foci may also be present on an enlarged spleen.
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The [[Bursa of Fabricius|'''bursa of fabricius''']] will usually initially be '''enlarged, oedematous and haemorrhagic.''' Its colour turns from white to cream and a '''yellow transudate''' covers its serosa early in infection.
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From 7-8 days following infection, the bursa '''atrophies''' and becomes approximately '''1/3''' of its original weight.
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===Laboratory Tests===
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IBDV antigen can be detected in cloacal bursa or splenic samples by '''Agar Gel Precipitation''' or '''[[Immunofluorescence]]'''. RT-PCR is commonly used to detect IBDV.
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'''Antibody [[ELISA testing|ELISA]]''' can be used for serological diagnosis within a flock. A mimimum of 30 samples is required.
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==Treatment==
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'''No treatment''' is available and recovery is usually rapid in an infected flock.
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==Control==
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'''Hygienic''' measures with appropriate disinfectants are imperative.
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'''Vaccination''' is also usually required. Both live and inactivated forms are available. Timing is difficult due to interference of maternally-derived antibody, but oil adjuvanted vaccines can extend maternal immunity to 5 weeks. Vaccination can cause immunosuppression and a degree of bursal damage.
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{{Learning
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|flashcards = [[Infectious Bursal Disease Flashcards]]
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}}
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==References==
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Eterradossi, N. and Saif, Y.M. (2008) '''Infectious Bursal Disease'''. In: '''Diseases of Poultry, 12th Edition''' (eds. Saif, Y.M., Fadly A.M., Glissen J.R., McDougald L.R., Nolan L.K., Swayne D.E.) ''Wiley-Blackwell'', pp 185-208
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van den Berg, T. (2007) '''Birnaviridae'''. In: '''Poultry Diseases, 6th Edition''' (eds. Pattison, M., McMullin, P., Bradbury, J., Alexander, D.) ''Saunders, Elsevier'', pp 359-366
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{{CABI source
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|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=80665&loadmodule=datasheet&page=2144&site=160 infectious bursal disease] and [http://www.cabi.org/ahpc/?compid=3&dsid=79279&loadmodule=datasheet&page=2144&site=160 infectious bursal disease virus]
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|date =5 June 2011
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}}
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<br><br>
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{{Dave Cavanagh
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|date = 23 August 2011
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}}
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{{OpenPages}}
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[[Category:Avian Viruses]]
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[[Category:Birnaviridae]]
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[[Category:Lymphoreticular and Haematopoietic Diseases - Birds]]
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[[Category:CABI Expert Review Completed]][[Category:CABI AHPC Pages]]
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