Avian pneumovirus infections (swollen head syndrome)

Occurrence: Europe, South Africa, Middle East, Asia.
Species affected: Chickens and turkeys.
Age affected: All.
Causes: Pneumovirus is a single-stranded, 80-200nm RNA virus.
Effects: Sneezing and nasal discharge, foamy conjunctivitis, swelling of infra-orbital sinuses, submandibular oedema, torticollis and cerebral disorientation may occur. Drop in egg production in layers. Mortality 0-10%.
Special note: Swollen Head Syndrome is a common problem in broiler breeders and occasionally in broilers and layers in Europe and South Africa.



Swollen head syndrome is a chronic disease affecting chickens and turkeys of all ages. Avian pneumovirus is a non-hemagglutinating, nonsegmented, enveloped single stranded RNA virus of the family Paramyxoviridae family with helical capsid symmetry (80-200 nm). It is spread by airborne and mechanical routes (feed, water, and equipment). Immunosuppression plays a role, and E. coli is a common secondary invader. Swollen heads are typically seen following a severe reaction to NDV-IBV vaccination in stressed immunosuppressed birds. In the United States turkey rhinotracheitis is caused by a bacteria (Bordetella avium).

Clinical signs

Signs include snicking, rales, sneezing, nasal discharge, foamy conjunctivitis, and swelling of the infraorbital sinuses. Submandibular oedema, mortality 0-10%, torticollis, and cerebral disorientation may occur. A drop in egg production, whitish colour of eggs and morbidity approaching 100% of the flock may also be seen.

Postmortem lesions

Yellow oedema and/or haemorrhaging in nasal turbinates, larynx, trachea and subcutaneous layer of skin around head can be evident.


Viral isolation from the trachea, lungs or nasal exudate in embryonating turkey eggs, chicken organ cultures, and PCR are diagnostic. Serological tests include virus neutralisation, and ELISA. It simulates many respiratory diseases including influenza, bronchitis, mycoplasma, E. coli, and infectious coryza.

Treatment & control

Live vaccines are usually given by spray or drinking water for broiler breeders and broilers and/or killed vaccines for broiler breeders and breeding turkeys are available in Europe, the Middle East, and Latin America.

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