Sensitivity of test strategies used in the Voluntary Johne's Disease Herd Status Program for detection of Mycobacterium paratuberculosis infection in dairy cattle herds

Scott J. Wells Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108.

Search for other papers by Scott J. Wells in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACVPM
,
Robert H. Whitlock Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348.

Search for other papers by Robert H. Whitlock in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACVIM
,
Bruce A. Wagner Centers for Epidemiology and Animal Health, USDA:APHIS:VS, Fort Collins, CO 80521.

Search for other papers by Bruce A. Wagner in
Current site
Google Scholar
PubMed
Close
 MS
,
James Collins Department of Diagnostic Medicine, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108.

Search for other papers by James Collins in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
Franklyn Garry Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

Search for other papers by Franklyn Garry in
Current site
Google Scholar
PubMed
Close
 DVM, MS
,
Heather Hirst Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

Search for other papers by Heather Hirst in
Current site
Google Scholar
PubMed
Close
 DVM, MS
,
John Lawrence IDEXX Laboratories, 1 IDEXX Dr, Westbrook, ME 04092.

Search for other papers by John Lawrence in
Current site
Google Scholar
PubMed
Close
 BS
,
William J. A. Saville Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

Search for other papers by William J. A. Saville in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACVIM
, and
Alecia L. Larew Naugle Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

Search for other papers by Alecia L. Larew Naugle in
Current site
Google Scholar
PubMed
Close
 DVM

Abstract

Objective—To evaluate sensitivities at the herd level of test strategies used in the Voluntary Johne's Disease Herd Status Program (VJDHSP) and alternative test strategies for detecting dairy cattle herds infected with Mycobacterium paratuberculosis.

Design—Nonrandom cross-sectional study.

Sample Population—64 dairy herds from Pennsylvania, Minnesota, Colorado, Ohio, and Wisconsin. Fifty-six herds had at least 1 cow shedding M paratuberculosis in feces; the other 8 herds were free from paratuberculosis.

Procedure—For all adult cows in each herd, serum samples were tested for antibodies to M paratuberculosis with an ELISA, and fecal samples were submitted for bacterial culture for M paratuberculosis. Sensitivities at the herd level (probability of detecting infected herd) of various testing strategies were then evaluated.

Results—Sensitivity at the herd level of the testing strategy used in level 1 of the VJDHSP (use of the ELISA to test samples from 30 cows followed by confirmatory bacterial culture of feces from cows with positive ELISA result) ranged from 33 to 84% for infected herds, depending on percentage of cows in the herd with positive bacterial culture results. If follow- up bacterial culture was not used to confirm positive ELISA results, sensitivity ranged from 70 to 93%, but probability of identifying uninfected herds as infected was 89%.

Conclusions and Clinical Relevance—Results suggest that the testing strategy used in the VJDHSP will fail to identify as infected most dairy herds with a low prevalence of paratuberculosis. A higher percentage of infected herds was detected if follow-up bacterial culture was not used, but this test strategy was associated with a high probability of misclassifying uninfected herds. (J Am Vet Med Assoc 2002;220: 1053–1057)

Abstract

Objective—To evaluate sensitivities at the herd level of test strategies used in the Voluntary Johne's Disease Herd Status Program (VJDHSP) and alternative test strategies for detecting dairy cattle herds infected with Mycobacterium paratuberculosis.

Design—Nonrandom cross-sectional study.

Sample Population—64 dairy herds from Pennsylvania, Minnesota, Colorado, Ohio, and Wisconsin. Fifty-six herds had at least 1 cow shedding M paratuberculosis in feces; the other 8 herds were free from paratuberculosis.

Procedure—For all adult cows in each herd, serum samples were tested for antibodies to M paratuberculosis with an ELISA, and fecal samples were submitted for bacterial culture for M paratuberculosis. Sensitivities at the herd level (probability of detecting infected herd) of various testing strategies were then evaluated.

Results—Sensitivity at the herd level of the testing strategy used in level 1 of the VJDHSP (use of the ELISA to test samples from 30 cows followed by confirmatory bacterial culture of feces from cows with positive ELISA result) ranged from 33 to 84% for infected herds, depending on percentage of cows in the herd with positive bacterial culture results. If follow- up bacterial culture was not used to confirm positive ELISA results, sensitivity ranged from 70 to 93%, but probability of identifying uninfected herds as infected was 89%.

Conclusions and Clinical Relevance—Results suggest that the testing strategy used in the VJDHSP will fail to identify as infected most dairy herds with a low prevalence of paratuberculosis. A higher percentage of infected herds was detected if follow-up bacterial culture was not used, but this test strategy was associated with a high probability of misclassifying uninfected herds. (J Am Vet Med Assoc 2002;220: 1053–1057)

All Time Past Year Past 30 Days
Abstract Views 60 0 0
Full Text Views 904 712 45
PDF Downloads 126 56 6
Advertisement