A comparison between and within two commercial ELISAs for bovine paratuberculosis

Authors: Venkatesh KM, Lopez-Villalobos N, Gupta SK, Udy G, Laven R, Sayoji V, Dukkipati R
Publication: Proceedings of the Epidemiology, Food Safety, Animal Welfare and Biosecurity, and Industry Branches of the NZVA, Volume 2025 Proceedings, pp 35-38, Jun 2025
Publisher: New Zealand Veterinary Association

Animal type: Cattle
Article class: Conference paper

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Abstract:

Bovine paratuberculosis is a chronic enteric disease caused by Mycobacterium avium subspecies paratuberculosis. This disease causes a considerable economic loss to the New Zealand dairy industry. Although the diagnostic tests for paratuberculosis are suboptimal, it is vital to evaluate the existing commercial diagnostic tests for their agreement, as they may contribute to disease surveillance programmes. This study compared (using kappa statistics) two enzyme-linked immunosorbent assay (ELISA)-based bovine paratuberculosis commercial antibody detection kits (IDEXX Paratuberculosis Screening Ab Test and ID Screen® Paratuberculosis Indirect Screening ELISA) using milk and serum samples from dairy cattle in New Zealand. A total of 1169 animals with mixed age and breed composition with at least one ELISA test were used in the present study. Finally, 930 scores of IDVet and Idexx milk ELISAs, 935 for IDVet serum ELISA, and 1121 of Idexx serum ELISA were used in the analysis. The results of the study were anonymised (kit A and kit B) to avoid conflicts of interest. The suspect outcome of the ELISA results was considered negative (case 1) and omitted from the analysis (case 2). The within-kit (milk vs. serum) agreement was higher for kit B (k = 0.84, CI: 0.75 - 0.93) than for kit A (k = 0.76, CI: 0.66 - 0.87) for case 2. The between-kit agreement was higher for serum samples (k = 0.93, CI: 0.87 - 0.99) than that of milk (k = 0.80, CI: 0.71 - 0.89) samples for case 2. These results suggest that serum samples would be a better choice if both commercial kits A and B were used for bovine paratuberculosis surveillance in New Zealand. However, future studies with a larger sample size from herds with different disease definitions, age distribution, and immune spectra of the host are needed to validate the results of the present study.

Keywords: Antibody detection assays, Cattle, enzyme-linked immunosorbent assay, Kappa, Mycobacterium avium subsp. Paratuberculosis

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