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Also Known As: '''''Turkey Rhinotracheitis Virus — Swollen Head Syndrome — APV — TRTV — TRV'''''
==Introduction==
Avian Pneumovirus is a pneumovirus, a type of '''[[Paramyxoviridae |paramyxovirus]]''' causing '''respiratory disease''' in turkeys and chickens. It is one of the most important [[Viruses |viral]] respiratory diseases of turkeys.
TRV is not zoonotic.
==Distribution==
The virus is widespread in '''Europe'''. It is known to be present in Asia, Africa, the Middle East South America and North America too.
TRTV can replicate in the reproductive and respiratory systems. Its transmission is mainly oral.
==Signalment==
'''Turkeys''' are generally more susceptible to the disease than chickens, and other domesticated species e.g. pheasants, guinea fowl, are affected. '''Intensive''' rearing systems with high stocking density are conducive to spread of the disease.
==Clinical Signs==
Clinical signs usually begin 3 days after infection but are mild initially. '''Mortality''' is highest in turkey '''poults''' and is usually due to secondary bacterial infection.
Respiratory disease is most common and causes '''tachypnoea, nasal discharge, dyspnoea, sneezing and abnormal breathing'''. Clinical disease is usually accompanied by a '''decrease in egg production''' and reproductive failure. Folded egg membranes and egg peritonitis may develop consequentially.
'''Torticollis''', reluctance to move, swelling of the head, face and eyes and head shaking are manifestations of more severe cases.
'''Lack of growth''' and retardation will occur in young birds infected by TRV.
==Diagnosis==
Serological diagnosis can be achieved by '''[[ELISA testing |ELISA]]'''. '''[[Immunofluorescence|Indirect immunofluorescence]]''' and '''viral neutralisation''' can be applied to tissue sections, though detection by RT-PCR is now the most common approach.
'''Viral isolation''' can be attempted from nasal turbinates, trachea or exudates, oesophagus and buccal cavity, and is most successful in turkeys.
'''Necropsy''' findings can also be suggestive:
:'''Turkeys''':
::'''Clear to greyish exudate''' is present in the nasal turbinates and excess '''mucus''' is present in the trachea. Inflammatory exudates is evident microscopically.
::In hens, oviductal infection is represented by '''inspissated albumen''' forming white masses. Misshapen eggs may be present and ovarian regression evident.
:'''Other fowl'''
::'''Turbinate mucosae''' are discoloured '''red-purple''' by petechiation. The subcutaneous tissues covering the head are oedematous with fibrinopurulent inflammation. Pericarditis and perihepatitis are regularly seen.
::Egg peritonitis is also sometimes found.
==Treatment==
There is '''no treatment''' for the viral infection but '''antibiotics''' administered in drinking water may minimise losses by treating secondary bacterial infection.
==Control==
'''[[Vaccines]]''' are available against type A and B TRV for both turkeys and chickens, and are the main form of control in endemic countries. Killed vaccines must be first '''primed''' with a live vaccine to be effective.
Good '''biosecurity''' should always be practised including particular attention to storage and disposal of carcasses on the unit. Air quality should be monitored and maximised and birds of different ages segregated wherever possible.
{{Learning
|flashcards = [[Turkey Rhinotracheitis Virus Flashcards]]
}}
==References==
<references/>
{{CABI source
|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=92920&loadmodule=datasheet&page=2144&site=160 turkey rhinotracheitis virus] and [http://www.cabi.org/ahpc/?compid=3&dsid=60956&loadmodule=datasheet&page=2144&site=160 turkey rhinotracheitis]
|date = 6 June 2011
}}
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[[Category:CABI Expert Review]]
[[Category:Avian Viruses]]
[[Category:Paramyxoviridae]]
[[Category:Respiratory Diseases - Birds]]