Comparison of Tuberculin Skin Test, IFN-gamma Assay, Real Time PCR and Lateral Flow Rapid Test in Diagnosis of Field Outbreaks of Bovine Tuberculosis

Abstract

Bovine tuberculosis is an important zoonotic disease transmitted by direct contact, respiratory pathway, ingestion of unpasteurised milk and milk product, raw or undercooked meat. Tuberculosis can be difficult to diagnose based only on the clinical signs. Tuberculosis is usually diagnosed in the field with the tuberculin skin test. Sputum and other body fluids may be collected for microbiological examination. Polymerase chain reaction (PCR) methods have also been described. Diagnostic blood tests include the lymphocyte proliferation assay, the interferon gamma (IFN-gamma) assay, and enzyme-linked immunosorbent assays (ELISA). In this study a total of 50 animals were tested by using tuberculin skin test (TST), lateral flow rapid test, IFN-gamma assay and real time PCR. The animals were selected randomly among 178 cattle in dairy farms with the aged between 3-5 years and suspected of having tuberculosis. Forty five cattle were positive out of 50 for TST while 31 for reactive by the IFN-gamma assay and 28 for rapid test and 9 for real time PCR. The purpose behind such variable as age was to compare sensitivity of tuberculin skin test, the IFN-gamma assay and TB lateral flow rapid test and real time PCR examination for the diagnosis of field outbreaks of bovine tuberculosis in Turkey.