An upper respiratory disease of commercial chickens resembling infectious coryza, but caused by a V factor‐independent bacterium

Abstract

From early 1989 the emergence of an infectious bacterial disease resembling infectious coryza was seen in several commercial chicken flocks in Natal Province of South Africa. Clinical signs were facial swelling and nasal discharge. An organism was routinely isolated from the infra-orbital sinus or trachea of infected chickens. The organism was found to be a Gram-negative rod, non-motile, V factor (nicotinamide adenine dinucleotide, NAD)-independent, catalase negative, oxidase positive and urease and indole negative. No gas was produced from carbohydrates and acid was produced from glucose, mannitol, inositol and sorbitol. Experimental inoculation of this organism into the infraorbital sinus of SPF chickens and conventional broilers produced an acute upper respiratory disease. The organism could be recovered for up to 7 days post-inoculation. The organism is closely related to Haemophilus paragallinarum, the cause of infectious coryza, but because it is NAD-independent it cannot be classed as an Haemophilus species.