Avian pneumovirus

Avian metapneumovirus (also known as Turkey Rhinotracheitis Virus − Swollen Head Syndrome) is a virus which infects primarily turkeys and, to a lesser extent, chickens. Other domesticated fowl such as pheasants can also be affected.

Transmission is via the respiratory tract and the disease is widespread over most continents. High stocking density allows the virus to spread more easily.