header shadow

Johne's ELISA

A  B  C  D  E  F G H  I  J  K  L  M  N  O  P  Q  R  S  T U  V  W    VDPAM INDEX


May 13, 2010

Johne's Antibody Assay

The serology section is now using  Idexx's new Mycobacterium paratuberculosis (M. pt.) ELISA antibody test kit.  This new assay can effectively evaluate M. pt.  antibody levels in bovine serum, plasma, and milk.  The ability to use milk or plasma as acceptable samples  will be new features of  this assay.  Improved sensitivity and the ability to test milk samples  are the major advantage of this assay. 

The data below summarizes three separate studies conducted by Idexx using serum in study 1, plasma in study 2, and milk in study 3.   The ELISA results in the study were compared to M. pt. culture results. Any of the three sample types tested showed improved sensitivity  when compared current antibody assays.  The 74.2% sensitivity when using milk as the test sample is very exciting.  The assay while not approved for use in small ruminants in the United States  is widely used in Europe for the screening of sheep and goat serum  samples for antibodies to M. pt. 


VDL Submission forms  

Fee Schedule


Dr. David Baum
ISU VDL Serology Section Head



Relative Sensitivity and Specificity
using characterized positive and negative samples
Study ID ELISA+/Cul+ ELISA-/Cul+ ELISA+/Cul- ELISA-/Cul- Sample type Relative sens./spec.
1 127 120 5 712 serum vs cul. 51.4% / 99.3%
2 45 37 0 174 plasma vs cul. 54.9% / 100%
3 92 32 1 633 milk vs cul. 74.2% / 99.8%