Avian Infectious Bronchitis
Also Known As: Infectious Bronchitis
Caused By: Avian Infectious Bronchitis Virus also know as: AIBV — IBV — AIB — IB
IBV is transmitted mainly by aerosols and also by contaminated people/vehicles/equipment.
It can become persistent in a bird and recrudesce with stress, e.g. at point of lay.
Chickens are the only known natural host of IBV. Other birds are affected by genetically similar yet distinct avian coronaviruses.
Disease is most severe in chicks.
Reduced weight gain or egg production and reluctance to move is often the first indicator of disease.
- Sneezing, coughing, dyspnoea, tracheal rales, ingesta present in respiratory passages, nasal discharge, abnormal lung sounds on auscultation
Alimentary and Urinary Signs:
- Wet droppings, dehydration, polydipsia
- Polyuria, Pollakiuria
- Reluctance to move
- Swelling of the head and face
- Conjunctival congestion and increased lacrimation or ocular discharge
- Soft egg shells, thin albumin and watery yolks
In the acute phase, viral isolation can be attempted from tracheal swabs or tracheal/lung biopsies.
If more than one week after initial infection, caecal tonsils or cloacal swabs are more reliable.
RT-PCR can be performed on buccal or oropharyngeal swabs.
Agar Gel Precipitation and Immunofluorescent Antibody (IFAT) tests can also be used to detect the virus.
On post-mortem examination, yellow catarrhal or caseous exudates are present in the trachea, nasal passages, sinuses and air sacs.
On histopathology of the trachea, loss of cilia and sloughing with heterophilic infiltration is evident.
The kidneys are pale and swollen and tubules distended with urates if nephritis is also present. Heterophilic inflammation and degeneration may be evident.
Detection of viral antibodies is also valuable in surveillance and monitoring of vaccination. This can be performed using Agar Gel Immunodiffusion (AGID) , ELISA, Virus Neutralisation (VN) and Haemagglutination-Inhibition (HI).
RT-PCR, VN and HI can also be used to type IBV isolates.
No treatment is available for the viral infection.
Use of antibiotics in drinking water to treat and prevent secondary infection may reduce mortality and losses.
Live and Killed IBV vaccines are available and widely used but cross-protection is poor and numerous serotypes exist so disease is not always prevented. Vaccinations can be administered as intra-muscular injections (killed vaccines) or sprays/drinking water (live vaccines). Killed vaccines used alone do not induce immunity and therefore live vaccines are required to prime immunity first.
Good biosecurity and hygiene protocols are imperative to control this highly contagious disease. Particular efforts should be made with respect to ventilation and air quality.
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Cavanagh, D. and Gelb Jr, J. (2008) Infectious Bronchitis. 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 117-135
Cook, J.K.A. (2007) Coronaviridae. In: Poultry Diseases, 6th Edition (eds. Pattison, M., McMullin, P., Bradbury, J., Alexander, D.) Saunders, Elsevier, pp 340-350
Animal Health & Production Compendium, Avian Infectious Bronchitis datasheet, accessed 04/06/2011 @ http://www.cabi.org/ahpc/
The datasheet was accessed on 25/06/2011.
This article has been expert reviewed by Prof Dave Cavanagh BSc, PhD, DSc
Date reviewed: 23 August 2011
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