4. Etiology

Since its identification in 1898, Mycobacterium bovis (later split into two subspecies: M. bovis subsp. bovis and M. bovis subsp. caprae) has been considered as the etiological agent of tuberculosis but later, other members of the Mycobacterium tuberculosis complex (MTBC) were found to cause similar infections [2–4]. More recently, species of mycobacteria hitherto regarded as saprophytic and nonpathogenic, referred to as nontuberculous mycobacteria (NTM) and more recently, mycobacteria other than tuberculosis (MOTTs) have been identified as causative agents [4, 5]. Apart from the requirement for isolation and identification of the causative for confirmatory diagnosis, these species have complicated interpretation of in vivo diagnostic tests, such as the tuberculin test, due to the expected cross-reactive immune responses [6, 7]. Some of these MOTTs have also been found to cause a variety of infections in humans and should therefore be considered potentially as zoonotic, and infestations in cattle and other animals as important and the MTBC. Many other species of animals are also susceptible to M. bovis. These include wildlife species, which constitute reservoirs of infection for domestic animals [8, 9]. Transmission to domestic animals and humans is therefore potentially an outcome of humanwildlife conflict. With such a variety of mycobacteria species, now associated with tuberculosis in cattle, perhaps the etiological term mycobacteriosis, rather than the pathological term tuberculosis, should be more applicable. This chapter will explore the etiology, epidemiology, pathogenesis, pathology, diagnosis, public health importance, and control of tuberculosis in cattle. It is expected that the chapter will be found useful by veterinary students, tutors, animal

Tuberculosis is an infectious, chronic or acute, localized or disseminated granulomatous disease that affects mammals, fish, and birds, caused by members of the genus Mycobacterium. In cattle, the disease is caused by obligatory pathogenic and opportunistic species of mycobacteria. Animals affected by the disseminated infection progressively emaciate and finally succumb to the infection. The importance of the disease is its zoonosis and the economic losses

Tuberculosis affects warm- and cold-blooded animals and it is estimated that it has been around for more than 3 million years [10]. The disease in cattle was first observed by the Spaniard farmer, Lucius Junius Moderatus Columella in Northern Italy in the year 14 AD [11]. In 1881, Robert Koch discovered Mycobacterium tuberculosis (tubercle bacillus) as the cause of tuberculosis in humans and in 1882, established the connection between human and animal tuberculosis through the observation that consumption of contaminated cow's milk led to infection. In 1898, Theobald Smith identified M. bovis as a different species from M. tuberculosis.

The first compulsory milk pasteurization law was enacted in UK in 1908 following the research that linked consumption of raw milk to extrapulmonary tuberculosis; two French scientists Albert Calmette and Camille Guerin developed the Bacillus Calmette-Guerin (BCG) vaccine for immunizing humans against tuberculosis, by attenuating M. bovis through subculture. The vaccine was first used in 1921 [12]. In 1890, Robert Koch extracted tuberculin from the tubercle

health service providers, and researchers.

2. Definition

Bacterial Cattle Diseases

it causes.

3. History

64
