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Pathogenicity differences between South African isolates of Ornithobacterium rhinotracheale
A F Travers1, L Coetzee, B Gummow
1Department of Poultry Diseases, Faculty of Veterinary Science, University of Pretoria, South Africa.
The Onderstepoort Journal of Veterinary Research
|September 1, 1996
Summary
Three Ornithobacterium rhinotracheale field isolates caused significant mass loss and disease in broilers. The study highlights the economic impact of O. rhinotracheale infections in poultry farming.
Area of Science:
- Veterinary Microbiology
- Avian Pathology
- Poultry Diseases
Background:
- Ornithobacterium rhinotracheale (ORT) is an emerging pathogen in poultry.
- ORT infections can cause significant economic losses in the poultry industry.
- Understanding the pathogenicity of different ORT isolates is crucial for disease control.
Purpose of the Study:
- To evaluate the pathogenicity of three South African Ornithobacterium rhinotracheale field isolates in broilers.
- To determine the clinical signs, gross lesions, and reisolation potential of ORT from infected birds.
- To compare the pathogenicity and symptomatology among different ORT isolates.
Main Methods:
- Three ORT field isolates were identified and inoculated into 28-day-old broilers via the caudal abdominal airsac.
- Birds were monitored under controlled laboratory conditions for clinical signs and mortality.
- Post-mortem examinations included gross lesion scoring for airsacculitis and arthritis, and bacterial reisolation from various tissues, including the brain.
Main Results:
- All three ORT isolates were capable of causing primary disease, leading to statistically significant mass loss.
- Respiratory signs and arthritis were reproduced, but sinusitis was not observed.
- Significant differences in pathogenicity, airsacculitis and arthritis lesion scores, and symptomatology were observed between the isolates.
- Ornithobacterium rhinotracheale was highly significantly reisolated from the brains of broilers challenged with isolate 2.
Conclusions:
- The selected ORT isolates demonstrated pathogenicity in broilers, causing significant economic losses.
- Pathogenicity and clinical presentation varied among the different ORT isolates.
- The reisolation of ORT from the brain indicates potential for systemic spread and neurological involvement, emphasizing the economic importance of ORT infections in poultry.