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Ornithobacterium rhinotracheale (view source)
Revision as of 09:33, 22 June 2011
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[[Category:To Do - Steph]]
==Introduction==
'''''Ornithobacterium rhinotracheale''''' is a '''gram negative rod shaped [[Bacteria|bacterium]]''' causing '''[[Respiratory System|respiratory]] disease in turkeys and chickens'''. It is the only bacterium currently classified as within the ''Ornithobacterium'' genus.
The bacterium is non-haemolytic and can tolerate a range of aerobic/anaerobic conditions and colonise a variety of agars. Colonies are smooth and non-pigmented. 12 serotypes of O. rhinotracheale have been distinguished, and are mainly defined geographically.
O. rhinotracheale is not zoonotic.
==Distribution==
Worldwide
Transmission is '''vertical through eggs and also aerosolic'''.<ref name="Van Empel">Van Empel, P. C. M., Hafez, H. M (1999) Ornithobacterium rhinotracheale: a review. Avian Pathology, 28(3):217-227.</ref>
==Signalment==
Birds of all ages can be affected.
In turkeys, disease is more severe in '''adult birds from market age''' onwards.<ref>Roepke, D. C., Back, A., Shaw, D. P., Nagaraja, K. V., Sprenger, S. J., Halvorson, D. A (1998) '''Isolation and identification of Ornithobacterium rhinotracheale from commercial turkey flocks in the upper midwest.''' Avian Diseases, 42(1):219-221; 7</ref>
'''Male birds also appear to be more susceptible''' to clinical signs and mortalities.<ref>Zormal- Rojs, O., Zdovc, I., Bencina, D., Mrzel, I (2000) '''Infection of turkeys with Ornithobacterium rhinotracheale and Mycoplasma synoviae.''' Avian Diseases, 44(4):1017-1022.</ref>
Disease is seen primarily in '''broiler chickens and meat turkeys''' but also affects layers. Various wild birds including pheasants, partridges, guinea fowl and rooks have also been found to be infected.<ref>Leroy- Sétrin, S., Flaujac, G., Thénaisy, K., Chaslus-Dancla, E (1998) '''Genetic diversity of Ornithobacterium rhinotracheale strains isolated from poultry in France.''' Letters in Applied Microbiology, 26(3):189-193; 16</ref>
==Clinical Signs==
'''Nasal discharge, dyspnoea, sneezing and a productive cough which may yield blood''' represent the purulent pneumonia caused by ''O. rhinotracheale'' infection. Birds often exhibit '''severe growth retardation''' and mortalities within the flock will increase.
''O. rhinotracheale'' has also been associated with '''hatching problems''' in chickens and turkeys<ref>E-Gohary, A. A (1998) '''Ornithobacterium rhinotracheale (ORT) associated with hatching problems in chicken and turkey eggs.''' Vet Med J Giza, 46(2):183-191; 19</ref> and production of '''soft-shelled misshapen eggs.'''
Infection can also spread haematogenously to the '''joints''' and cause lameness and swelling.
[[Alimentary System|Gastrointestinal]] signs such as [[Diarrhoea|diarrhoea]] and concurrent weight loss and ill thrift are seen in some birds. [[Nervous System|Neurological]] signs may also develop in severe cases, usually consisting of tremors, fasciculations and paresis/paralysis.
==Diagnosis==
''O. rhinotracheale'' is most commonly isolated and cultured from the '''trachea and lungs''', but is possible from other organs. Blood agar is usually used for culture but overgrowth of other bacteria is a common complication. '''PCR<ref name="Van Empel" /> and Immunofluorescence''' are also possible.<ref>Lombardi, G., Vinco, L. J., Belloni, G. P., Alborali, G. L (1999) '''Incidence of Ornithobacterium rhinotracheale (ORT) in some turkey farms in Northern Italy: field observations and diagnosis.''' Selezione Veterinaria, No. 8/9:595-602; 15</ref>
'''Agar gel precipitation''' can be used for serological diagnosis and serotyping. '''[[ELISA testing|ELISA]] and serum agglutination''' can be used to detect antibodies to ''O. rhinotracheale''.
The most common post-mortem signs seen are '''air sacculitis and pneumonia''' but inflammatory suppurative lesions may be seen throughout the respiratory tract. The lungs and air sacs are infiltrated by '''lymphocytes and polymorphonuclear heterophils''' when examined histologically.<ref>Veen, L., Empel, P., Fabri, T (2000). '''Ornithobacterium rhinotracheale, a primary pathogen in broilers.''' Avian Diseases, 44(4):896-900; 6</ref> Degenerative changes may also be seen within the muscles and tendons. In turkeys, a serofibrinous pneumonia is seen and blood is often present in the trachea and bronchi. Coagulative necrosis of the liver is sometimes seen.
==Treatment==
'''No specific treatment is available and resistance to antibiotics is common.''' Therefore culture and sensitivity is recommended where O. rhinotracheale infection is suspected. Single and combination protocols involving '''oxytetracyclines, chlortetracycline, tiamulin, penicillins, spectinomycin and ceftiofur''' have been used but response is unpredictable.
==Control==
'''Vaccinations are under development''' and experimental trials suggest that vaccinating breeders with a bacterin and progeny with a live vaccine at 2-3 weeks old is the most effective method of controlling ''O. rhinotracheale''.
{{Learning
|flashcards = [[Ornithobacterium rhinotracheale Flashcards|''O rhinotracheale'' Flashcards]]
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==References==
<references/>
Animal Health & Production Compendium, '''Ornithobacterium rhinotracheale datasheet''', accessed 22/06/2011 @ http://www.cabi.org/ahpc/
Animal Health & Production Compendium, '''Ornithobacterium rhinotracheale infections datasheet''', accessed 21/06/2011 @ http://www.cabi.org/ahpc/
[[Category:To Do - CABI review]]