The problem associated with tuberculosis in cattle and how this is being addressed

Abstract

Bovine tuberculosis (bTB) is a zoonotic disease caused by Mycobacterium bovis that primarily infects cattle but has a wide range of hosts. It represents a global health problem affecting the livestock industry tremendously, with economic losses of about 3 billion annually. Dairy cattle produce a decline of 10% in terms of liters of milk produced and 5% in the meat industry because of live weight loss and seized carcasses in abattoirs. The core of the current control measures implemented in most countries against bTB is based on the diagnosis with tuberculin skin test (TST) and culling of infected animals. Unfortunately, control programs have failed to eradicate the disease since no vaccine protects cattle from infection. Moreover, the strain of M. bovis Bacillus Calmette Guerin, BCG used as a vaccine for human tuberculosis, interferes with surveillance tools. Nowadays, most researchers have been working on improving the efficacy of BCG through a prime-boost strategy that involves a first immunization with BCG and a booster with different types of vaccines. A less explored approach by experts has been the development of a new vaccine that only includes some protective antigens of M. bovis that should be absent ot in low representation in TST. On the other hand, because TST precludes implementation of Bacille Calmette-Guérin (BCG) vaccine–based control programs, several investigations have been carried out to replace the TST with a DIVA test that allows to differentiation infected from vaccinated animals. In this review, most of the studies cited agree that without an effective vaccine and a compatible diagnosis, no program for eradication would be successful against tuberculosis in cattle. Keywords: bovine tuberculosis; bTB; Mycobacterium bovis; diagnosis; tuberculin skin test, TST, bPPD; vaccines, DIVA.