Current status on the role of Ornithobacterium rhinotracheale (ORT) in respiratory disease complexes in poultry Derzeitiger Stand der Kenntnisse über die Bedeutung von Ornithobacterium rhinotracheale (ORT) bei Atemwegserkrankungen des Geflügels

Respiratory disease conditions are continuing to cause heavy economic losses in the poultry industry by increased mortality rates, increased medication costs, drops in egg production, reduction of egg shell quality, and decreases of hatchability . Since Dec. 1991 respiratory manifestations with different clinical courses have been observed in poultry flocks in different countries (Table 1 ). Bacteriological examinations have resulted in isolation of pleomorphic gramnegative rods (PGNR) from the lungs and airsacs of infected birds. Further identification using classical methods have failed to identify the organism. The described bacterium could not be isolated from poultry and avian materials exatnined in the Stuttgart State Veterinary Lab. from 1981 to 1991. Similar bacteria were isolated in the USA (CHARLTON et al., 1994) from chickens and turkeys suffering from respiratory diseases. In South Africa Du PREEZ (1992) described mild respiratory disease conditions accompanied with air sac turbidity in broilers between 26th and 30th day of age with mortality rate ranging between 12%. Bacteriological examination resulted in isolation of a similar micro-organism. The detected bacteria were designated as Pasteurella-like-organism or Taxon 28 until 1994. V ANDAMME et al. (1994) carried out further identification of isolates obtained from the respiratory tract of different avian species from different countries (Table 2) using genetic taxonomic methods and designated that bacterium as Ornithobacterium rhinotracheale gen. nov„ sp. nov. in the rR A-Superfamily V.