Open AccessApplication of the gamma‐interferon assay to determine the prevalence of bovine tuberculosis in slaughter livestock at abattoirs in Gauteng, South Africa
Author(s) -
Mareledwane Vuyokazi E.,
Adesiyun Abiodun A.,
Thompson Peter N.,
Hlokwe Tiny M.
Publication year - 2022
Publication title -
veterinary medicine and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 11
ISSN - 2053-1095
DOI - 10.1002/vms3.492
Subject(s) - livestock , bovine tuberculosis , veterinary medicine , feedlot , disease surveillance , tuberculosis , medicine , zoology , biology , environmental health , disease , mycobacterium bovis , mycobacterium tuberculosis , ecology , pathology
Background Bovine tuberculosis (bTB) is a zoonotic disease with great economic impact estimated at billions of dollars annually worldwide. Meat inspection represents a long‐standing form of disease surveillance that serves both food safety and animal health. The objective of this study was to determine the prevalence of bTB in livestock at abattoirs using a cell‐mediated immune (CMI) assay, the gamma interferon (IFN‐γ) assay. This cross‐sectional study was conducted at selected abattoirs (low‐throughput, high‐throughput and rural/informal) in Gauteng province, where animals were also subjected to routine meat inspection. Results A total of 410 fresh blood samples were collected from slaughter livestock (369 cattle and 41 sheep) from 15 abattoirs, and analysed using Bovigam ® test kit with bovine, avian and Fortuitum purified protein derivatives (PPD) as blood stimulating antigens. The estimated prevalence of bTB in cattle was 4.4% (95% CI: 2.4%–7.3%). The prevalence of bTB in cattle varied between abattoirs ( p = .005), ranging from 0% to 23%; however, there were no significant differences among genders, breeds, municipality, districts, origins of animals (feedlot, auction or farm) or throughput of abattoirs. The prevalence of avian reactors was 6.0% (95% CI: 3.6%–9.2%) in cattle, varying between abattoirs ( p = .004) and ranging from 0% to 20.7%. None of the sheep with valid test results was positive for bTB and none was avian reactors (95% CI: 0%–15%). Conclusion The detection of bTB reactor cattle in our study clearly shows the limitation of disease surveillance using a meat inspection approach, as all the 410 slaughter animals sampled had passed visual abattoir inspection and been classified as bTB‐free. Our findings therefore emphasize the risk of zoonotic transmission of bTB to abattoir workers and potential food safety hazard to consumers. Furthermore, our study highlights the potential for the use of the IFN‐γ assay to reduce this risk.