Multi-level Interpretation of the New IDEXX M. paratuberculosis ELISA on Serum and Milk Based on Likelihood Ratio Analysis

Authors

  • M. T. Collins Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706
  • N. Djuranovic IDEXX Laboratories, Westbrook, ME 04092
  • Lisa Estey IDEXX Laboratories, Westbrook, ME 04092
  • Valerie Leathers IDEXX Laboratories, Westbrook, ME 04092

DOI:

https://doi.org/10.21423/aabppro20104133

Keywords:

IDEXX ELISA, paratuberculosis, Mycobacterium avium, shedding, likelihood ratio, SIP ratios

Abstract

The new IDEXX ELISA for paratuberculosis measures the concentration of antibody in clinical samples, serum, plasma or milk. ELISA reader results, measured as optical density (OD) units, are transformed to SIP (sample/positive) ratios. Conventional ELISA interpretations employ a single cutoff for interpretation of SIP values as either negative (below the cutoff) or positive (above the cutoff). Prior studies demonstrated a strong correlation of SIP values with the probability animals are shedding Mycobacterium avium subsp paratuberculosis (MAP) in fecal samples collected at the same time as serum samples by likelihood ratio (LR) analysis, highlighting the clinical value of knowing the magnitude of SIP or equivalent transformed ELISA OD values ( Collins et al, 2005).

Cover image of the 43rd Conference Proceedings: Two short-horned cattle grazing in a field, surrounded by a flock of egrets. Yellow background.

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Published

2010-08-19

Issue

2010

Section

Research Summaries 2