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.
Avian pneumovirus infections (swollen head syndrome)
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).