Histopathological studies on the experimental infection of chickens with Ornithobacterium rhinotracheale "ORT"

Abstract

Respiratory affections are major problems in poultry industry . causing heavy economic losses through condemenation rate, mortality and medication costs. Several pathogens either singly or in combination are known to be able to induce pathological changes in the respiratory system. Among these pathogens are many bacteria, e.g pasteurella, B-Coli, Salmonella, haemophilus and mycoplasma. Many viruses are also responsible for affections of the respiratory system, examples are avian infleunza, avian infectious laryngeotracheitis, avian infectious bronchitis, New Castle disease virus (NCDV) , avian reovirus, avian pneumovirus and avian adenovirus. Other microorganisms are cryptosporidia and fungi.

In 1994, Van beek etal. reported respiratory disease of broiler chickens in

South Africa that presented unusual clinical signs.

Gram negative pleomorphic rod-shaped organisms were isolated. They were initially • designated as pasteurella-like • and later named ornithobacterium rhinotracheale (ORT) a name proposed by Vandamme etal. (1994) has recently been recognized in many countries world wide and incriminated as a possible additional causative agent in respiratory disease complex (Van Empel and Hafez • 1999). ORT is an acute contagious disease of Chickens and Turkeys. The severity are extermely variable and are infleunced by many enviromental factors such as poor management, inadequate ventilation, high stockingdensity, poor litter condition, poor hygiene, high amonia level, concurrent diseases and type of secondry infection.