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Aggregate testing for the evaluation of Johne's disease herd status
1New South Wales Agriculture, Queanbeyan.
Australian Veterinary Journal
|January 1, 1996
Summary
Evaluating herd Johne
Area of Science:
- Veterinary epidemiology
- Animal health surveillance
Background:
- Johne's disease (caused by Mycobacterium avium subspecies paratuberculosis) is a significant concern in the cattle industry.
- Accurate herd-level disease status evaluation is crucial for effective control and eradication programs.
Purpose of the Study:
- To examine aggregate testing methods for evaluating herd Johne's disease status in cattle industry surveys.
- To identify key parameters and challenges associated with aggregate testing for Johne's disease.
Main Methods:
- Discussion of aggregate testing, involving imperfect diagnostic tests (e.g., ELISA) on a random sample of cattle from a herd.
- Analysis of critical parameters: sample size, herd-level sensitivity and specificity, positive herd result criteria, and within-herd prevalence.
Main Results:
- Aggregate testing is potentially applicable to various livestock diseases.
- Challenges for Johne's disease include poor diagnostic test sensitivity, low within-herd infection prevalence, and clustering of false positives.
Conclusions:
- Aggregate testing presents specific difficulties when applied to Johne's disease surveillance in cattle.
- Further research may be needed to optimize diagnostic strategies for this disease.
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