Investigations of upper respiratory tract infections (URTI)
- Publication
- Organisation The University of Melbourne
- Researchers Amir Hadjinoormohammadi
This research project investigated upper respiratory tract infections (URTIs) in layer farms. URTIs cost the egg industry $35 million annually through reduced production, medication, vaccination, and mortality.
The two-phase study examined 17 farms cross-sectionally and monitored three farms through complete laying cycles using DNA analysis and conventional bacterial testing. Results showed URTIs result from polymicrobial infections involving twelve primary pathogens, including previously unreported bacteria typically associated with human periodontal disease.
Management practices significantly influenced infection rates. Farms using both slatted and deep litter flooring showed higher infection rates than those with slatted floors only. Flocks with outdoor access exceeding eight hours daily demonstrated increased susceptibility to respiratory infections.
Continuous monitoring revealed distinct pathogen patterns throughout production cycles. Mycoplasma species persist from pullet stage through end of lay, whilst Gallibacterium anatis emerges during rearing and Ornithobacterium rhinotracheale (ORT) appears before laying begins. Complex polymicrobial infections increase during peak production periods.
DNA analysis revealed substantial genetic diversity within ORT populations, with strains forming four distinct groups. Multiple ORT strains detected simultaneously on farms suggest current single-strain vaccines may provide incomplete protection.
A new DNA-based diagnostic protocol was developed detecting all conventional pathogens plus additional organisms, enabling comprehensive pathogen identification in a single test. These findings provide Australian farmers with scientific foundations for more effective disease control strategies.
The two-phase study examined 17 farms cross-sectionally and monitored three farms through complete laying cycles using DNA analysis and conventional bacterial testing. Results showed URTIs result from polymicrobial infections involving twelve primary pathogens, including previously unreported bacteria typically associated with human periodontal disease.
Management practices significantly influenced infection rates. Farms using both slatted and deep litter flooring showed higher infection rates than those with slatted floors only. Flocks with outdoor access exceeding eight hours daily demonstrated increased susceptibility to respiratory infections.
Continuous monitoring revealed distinct pathogen patterns throughout production cycles. Mycoplasma species persist from pullet stage through end of lay, whilst Gallibacterium anatis emerges during rearing and Ornithobacterium rhinotracheale (ORT) appears before laying begins. Complex polymicrobial infections increase during peak production periods.
DNA analysis revealed substantial genetic diversity within ORT populations, with strains forming four distinct groups. Multiple ORT strains detected simultaneously on farms suggest current single-strain vaccines may provide incomplete protection.
A new DNA-based diagnostic protocol was developed detecting all conventional pathogens plus additional organisms, enabling comprehensive pathogen identification in a single test. These findings provide Australian farmers with scientific foundations for more effective disease control strategies.
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