Diagnosis of Bovine Tuberculosis by Comparative Intradermal Tuberculin Test, Interferon Gamma Assay and esxB (CFP-10) PCR in Blood and Lymph Node Aspirates

Bovine tuberculosis (TB) is a chronic debilitating disease of huge economic importance due to loss in production, morbidity and mortality, and has a potential zoonotic threat. TB is endemic in India and has a worldwide prevalence, therefore, needing early diagnostic technique for the eradication of TB globally. Currently, compared to the eradication programme of TB in Medical sector, Veterinary sector is lagging behind though TB is one of the major zoonotic diseases prevalent in dairy animals and wildlife in India. With the “End TB” strategy by WHO in human, parallel measures for early diagnosis and culling has to be followed in case of animals for an overall successful eradication programme. The objective of this study is diagnosis of TB in cattle and buffaloes by using the cell-mediated immune response tests, i.e. Comparative Intradermal Tuberculin Test (CITT) and Interferon gamma (IFN-γ) assay, and Polymerase Chain Reaction (PCR) targeting esxB gene (CFP-10 protein) and to compare their diagnostic capabilities. This study was carried out in 202 dairy cattle and buffaloes from an organized dairy farm, where almost all of the animals appeared clinically healthy. We found that, the combined use of both CITT and IFN-γ assay lead to more accurate diagnosis of TB, although IFN-γ assay was more specific than CITT. However, esxB PCR showed almost similar sensitivity to IFN-γ assay and may be used as a fast alternative method for the diagnosis of bovine TB from blood samples.