| Title |
Estimating the true prevalence of paratuberculosis from the apparent prevalence when test sensitivity is not constant. |
| Author(s) |
Sockett DC,
Carr DJ,
Collins MT.
|
| Institution(s) |
School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706 and Wisconsin Department of Agriculture Trade and Consumer Protection, Madison, WI 53705 USA.
|
| Source |
Third International Colloquium on Paratuberculosis
|
| Section |
1:
Laboratory Diagnosis
|
| Abstract |
Samples from the National Repository for Paratuberculosis specimens were analyzed to determine if the prevalence of disease affected the sensitivity of the diagnostic tests. Logistic regression indicated that the prevalence of paratuberculosis significantly affected the sensitivity of conventional and radiometric fecal culture, a commercial DNA probe (IDEXX Corporation) and two commercial ELISA tests (Allied Laboratories and Commonwealth Serum Laboratories) (p less than 0.03). The standard complement fixation test (pless than 0.07) and commercial agarose immunodiffusion test (ImmuCell) (p less than 0.10) were not significantly affected. In addition, as the prevalence of paratuberculosis increased, the proportion of animals shedding M. paratuberculosis in their feces also increased (p less than 0.0001). This observed drop in test sensitivity as the prevalence of paratuberculosis declines has important implications for Johne's disease control programs.
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