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Kumar M, Kumar T, Jangir BL, Singh M, Arora D, Bangar Y, Conlan A, Vordermeier M, Bakker D, Byregowda SM, Srinivasan S, Kapur V, Jindal N. Comparative analysis of tuberculin and defined antigen skin tests for detection of bovine tuberculosis in buffaloes (Bubalus bubalis) in Haryana state, India. BMC Vet Res 2024; 20:65. [PMID: 38395846 PMCID: PMC11308649 DOI: 10.1186/s12917-024-03913-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 02/04/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND Bovine tuberculosis (bTB) is a chronic disease that results from infection with any member of the Mycobacterium tuberculosis complex. Infected animals are typically diagnosed with tuberculin-based intradermal skin tests according to World Organization of Animal Health which are presently in use. However, tuberculin is not suitable for use in BCG-vaccinated animals due to a high rate of false-positive reactions. Peptide-based defined skin test (DST) antigens have been identified using antigens (ESAT-6, CFP-10 and Rv3615c) which are absent from BCG, but their performance in buffaloes remains unknown. To assess the comparative performance of DST with the tuberculin-based single intradermal test (SIT) and the single intradermal comparative cervical test (SICCT), we screened 543 female buffaloes from 49 organized dairy farms in two districts of Haryana state in India. RESULTS We found that 37 (7%), 4 (1%) and 18 (3%) buffaloes were reactors with the SIT, SICCT and DST tests, respectively. Of the 37 SIT reactors, four were positive with SICCT and 12 were positive with the DST. The results show that none of the animals tested positive with all three tests, and 6 DST positive animals were SIT negative. Together, a total of 43 animals were reactors with SIT, DST, or both, and the two assays showed moderate agreement (Cohen's Kappa 0.41; 95% Confidence Interval (CI): 0.23, 0.59). In contrast, only slight agreement (Cohen's Kappa 0.18; 95% CI: 0.02, 0.34) was observed between SIT and SICCT. Using a Bayesian latent class model, we estimated test specificities of 96.5% (95% CI, 92-99%), 99.7% (95% CI: 98-100%) and 99.0% (95% CI: 97-100%) for SIT, SICCT and DST, respectively, but considerably lower sensitivities of 58% (95% CI: 35-87%), 9% (95% CI: 3-21%), and 34% (95% CI: 18-55%) albeit with broad and overlapping credible intervals. CONCLUSION Taken together, our investigation suggests that DST has a test specificity comparable with SICCT, and sensitivity intermediate between SIT and SICCT for the identification of buffaloes suspected of tuberculosis. Our study highlights an urgent need for future well-powered trials with detailed necropsy, with immunological and microbiological profiling of reactor and non-reactor animals to better define the underlying factors for the large observed discrepancies in assay performance, particularly between SIT and SICCT.
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Affiliation(s)
- Mohit Kumar
- Department of Veterinary Public Health and Epidemiology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125 004, India
| | - Tarun Kumar
- Veterinary Clinical Complex, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125 004, India
| | - Babu Lal Jangir
- Department of Veterinary Pathology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125 004, India
| | - Mahavir Singh
- College Central Laboratory, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125 004, India
| | - Devan Arora
- Regional Centre at Karnal, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125 004, India
| | - Yogesh Bangar
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125 004, India
| | - Andrew Conlan
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | | | - Douwe Bakker
- Technical Consultant and Independent Researcher, Lelystad, The Netherlands
| | - S M Byregowda
- Institute of Animal Health and Veterinary Biologicals, Bengaluru, India
| | - Sreenidhi Srinivasan
- Department of Animal Science, The Pennsylvania State University, University Park, PA, USA
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Vivek Kapur
- Department of Animal Science, The Pennsylvania State University, University Park, PA, USA
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Naresh Jindal
- Department of Veterinary Public Health and Epidemiology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125 004, India.
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