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Aggregate testing for the evaluation of Johne's disease herd status
Author(s) -
JORDAN D.
Publication year - 1996
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1996.tb09947.x
Subject(s) - herd , false positive paradox , disease , paratuberculosis , aggregate (composite) , veterinary medicine , statistics , medicine , environmental health , mathematics , tuberculosis , pathology , mycobacterium , materials science , composite material
SUMMARY This paper examines methods for evaluating herd Johne's disease status that could be used in a survey of the cattle industry. Emphasis is placed on aggregate testing, a process whereby a random sample of cattle from a herd is assessed using an imperfect test, such as an ELISA for detecting antibody in serum. Important aggregate test parameters discussed include: sample size, herd‐level sensitivity, herd‐level specificity, the number of reactors used for declaring a positive herd result, and the expected within‐herd prevalence of disease. Aggregate testing may be useful for several livestock diseases. However, problems arise when it is applied to Johne's disease because of the poor sensitivity of the available diagnostic tests, the low within herd prevalence of infection, and clustering of false positives within a herd.