Serological test performance for bovine tuberculosis in cattle from herds with evidence of on-going infection in Northern Ireland

PLoS One. 2021 Apr 13;16(4):e0245655. doi: 10.1371/journal.pone.0245655. eCollection 2021.

Abstract

The ability to accurately identify infected hosts is the cornerstone of effective disease control and eradication programs. In the case of bovine tuberculosis, accurately identifying infected individual animals has been challenging as all available tests exhibit limited discriminatory ability. Here we assess the utility of two serological tests (IDEXX Mycobacterium bovis Ab test and Enfer multiplex antibody assay) and assess their performance relative to skin test (Single Intradermal Comparative Cervical Tuberculin; SICCT), gamma-interferon (IFNγ) and post-mortem results in a Northern Ireland setting. Furthermore, we describe a case-study where one test was used in conjunction with statutory testing. Serological tests using samples taken prior to SICCT disclosed low proportions of animals as test positive (mean 3% positive), despite the cohort having high proportions with positive SICCT test under standard interpretation (121/921; 13%) or IFNγ (365/922; 40%) results. Furthermore, for animals with a post-mortem record (n = 286), there was a high proportion with TB visible lesions (27%) or with laboratory confirmed infection (25%). As a result, apparent sensitivities within this cohort was very low (≤15%), however the tests succeeded in achieving very high specificities (96-100%). During the case-study, 7/670 (1.04%) samples from SICCT negative animals from a large chronically infected herd were serology positive, with a further 17 animals being borderline positive (17/670; 2.54%). Nine of the borderline animals were voluntarily removed, none of which were found to be infected post-mortem (no lesions/bacteriology negative). One serology test negative animal was subsequently found to have lesions at slaughter with M. bovis confirmed in the laboratory.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle / blood*
  • Cattle / microbiology
  • Female
  • Male
  • Mycobacterium bovis / isolation & purification*
  • Northern Ireland / epidemiology
  • Serologic Tests
  • Tuberculin Test
  • Tuberculosis, Bovine / blood*
  • Tuberculosis, Bovine / diagnosis*
  • Tuberculosis, Bovine / epidemiology
  • Tuberculosis, Bovine / microbiology

Associated data

  • figshare/10.6084/m9.figshare.5705893

Grants and funding

This study was funded by the Department of Agriculture, Environment and Rural Affairs (DAERA) as part of the Evidence and Innovation Strategy under the grant “An assessment of commercially available serological tests for the detection of cattle infected with bovine tuberculosis” (grant no.: 15/3/09, Project Leaders: Dr. J. McNair and Dr. A. Byrne). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.