Concomitant Ornithobacterium rhinotracheale and Newcastle disease infection in broilers in South Africa.

Ornithobacterium rhinotracheale was first isolated from broilers in South Africa in 1991. The importance of O. rhinotracheale infections has been established, with growth suppression, respiratory symptoms, and arthritis commonly seen as complications. Dual infection with Newcastle disease and O. rhinotracheale in 28-day-old broilers led to more severe respiratory lesions and higher mortality rates than in birds with only Newcastle disease. It was concluded that the pathogenicity of Newcastle disease virus was enhanced when occurring in combination with O. rhinotracheale. Also of interest was the first isolation of O. rhinotracheale from the liver.