BACTERIAL AND PCR BASED DIAGNOSIS OF NATURALLY OCCURRING BOVINE TUBERCULOSIS IN CATTLE AND BUFFALOES

Abstract

Bovine tuberculosis causes huge economic losses to the dairy industry in terms of poor growth, reduce milk production potential of infected animals, emaciation and poor quality of carcass. Bovine tuberculosis due to Mycobacterium bovis is a major threat to public health. Therefore, this study was aimed at to know the frequency of Mycobacterium bovis infection in cattle and buffaloes. A total of 265 animals, including adult cattle (132) and buffaloes (133) of different age and sex were screened for tuberculosis infection with tuberculin test. Equal numbers of milk and nasal swab samples were collected from tuberculin reactor and non-reactor cattle and buffaloes for the isolation and identification of the causative organism. The infectious agent was identified and confirmed through procedures such as culture characteristics, ZN (Ziehl-Neelsen) staining, and PCR (Polymerase Chain Reaction) was also performed. The study revealed an overall 10.56% (95% C.I. 7.28 to 14.71) prevalence of bovine tuberculosis, the frequency of infectious agent was higher in buffaloes (11.04%) than cattle (9.76%). TB (Tuberculosis) was present in 100% herds. Multivariate logistic regression analysis with the backward elimination procedure revealed that, age (OR=1.564), body weight (OR=1.008) and status (OR=5.72) showed a significant association with the occurrence of tuberculosis. Nasal samples yielded more positive PCR results than milk samples. By considering PCR as a gold standard, ZN was more sensitive and PPD was a more specific test. Among all tests, PCR proved most accurate and fast test for the confirmation of bovine tuberculosis.