Infection of Ornithobacterium rhinotracheale (ORT) and its signs, importance and pathogenicity in the poultry industry of Iran: a review article

Ornithobacterium rhinotracheale (ORT) infection is a contagious bacterial disease of avian species, primarily chickens and turkeys which associated with respiratory distress, mortality, and increased slaughter condemnation rates, and high economic losses in the poultry industry throughout the world annually. Signs seen in natural and experimental infections, simultaneous infections with other respiratory pathogens and public health and economic importance of the disease have been analyzed and reviewed in this article. Respiratory signs such as pneumonia, nervous signs, reduced growth, Egg drop and ascites have been observed in commercial chickens of Iran. Observation of purulent cast into the trachea and bronchi and heavy mortalities are common signs of natural and or experimental ORT and influenza virus H9N2 co-infection in Iran. This sign or any mortality was not seen in the case of influenza H9N2 virus experimental infection alone. ORT infection has been reported with high prevalence in various breeds of commercial chicken flocks and also in turkeys. Pathogenicity of ORT strains are not the same and so it is possible to emerge strains with high pathogenicity in poultry industry of Iran. Only a few works have described some of the virulence factors of this bacterium such as non-siderophores iron acquisition mechanisms, neurominidase enzymatic activity, and a hemolysin-like protein. To deal with the disease, some ways including vaccination by autogenous vaccine, drug treatment based on antibiogram and stresses and other pathogens management are effective. Lowering the slaughter age in broilers is another way to deal with the heavy losses caused by ORT infections.