Evaluation of sensitivity and specificity of bovine Gamma-Interferon In-Vitro Assay for Diagnosis of tuberculosis in buffaloes

ABSTRACT

The sensitivity and specificity of the Bovine Gamma Interferon [IFN-lambda] in-vitro assay [BOVI-GAM] in the diagnosis of bovine tuberculousis in buffaloes as compared to the single intradermal cervical tuberculin test [SICT] and cultural isolation of Mycobacterium bovis were investigated. Thirty buffaloes from a dairy farm, in which tuberculin positive animals had been previously diagnosed, were tested. In the SICT test examined buffaloes 36.7% were positive and 23.3% were doubtful as compared with 53.3% positive and 16.7% doubtful results using the IFN- lambda assay. Two animals were positive to avian tuberculin in the IFN- lambda assay. The prevalence rate reached 60% and 70% using the SICT test and the IFN- lambda assay respectively. The sensitivity of the SICT and the IFN- lambda assay as compared with the cultural isolation of M. bovis were 75% and 95%, respectively, while the specificity were 70% and 80%, respectively. M. bovis was isolated from five buffaloes that were negative to SICT and one buffalo that was negative to the IFN- lambda assay. In conclusion, the present study demonstrated that the IFN- lambda assay is a practical, more sensitive and specific in-vitro diagnostic test than the conventional tuberculin test for detection of bovine tuberculosis in buffaloes