Bovine Tuberculosis

[Name of the institute]Bovine Tuberculosis

Natural History

Bovine tuberculosis is an infectious disease that is present in the world for centuries. The causative agent of bovine tuberculosis in humans, Mycobacterium tuberculosis, has been found in Egyptian mummies dating back over 5000 years ago. In animals, Mycobacterium bovis is the major causative agent of tuberculosis, especially in cattle and wild ruminant species and although there are no historical reports of its prevalence, the disease was recognized as a problem of livestock, especially in the nineteenth century. Other less common mycobacterium that cause bovine tuberculosis in animals are M. microti affecting wild rodents, M. caprae and M. pinnipedi affecting goats and seals, respectively (Menzies & Neill, 2000).

Although cattle are the main species affected by M. bovis, a wide range of mammalian species may serve as a reservoir or who develop the disease, as humans, so even today is an important disease. The industrialization of livestock in the nineteenth century increased human contact with livestock, just at the time of the identification of M. tuberculosis by Robert Koch (1882), which coupled with the rise in TB cases in humans led to the idea that M. M. tuberculosis descended from bovis. However, comparative genomic studies show that although both species have pathogenic 99.95% identity in the genomic sequences, the genome of M. bovis is smaller, suggesting that a pathogen could be younger than M. tuberculosis. Precisely because of the similarity between the lesions in cattle and humans and the proximity between the two species that generate them, was first used by M. bovis in humans as a vaccine against M. tuberculosis but there was also caused disease. It was not until after 230 passages in culture and just over 10 years, Albert Calmette and Camille Guerin attenuated strain of M. bovis (BCG, Bacille Calmette-Guerin) in 1919 and successfully used as a vaccine in 1923, which itself derived strains that are currently used to vaccinate most of the human population worldwide. Currently in developed countries have strategies for the eradication of bovine tuberculosis through screening programs and disposal of cases, which are expected to enhance the application of vaccines for cattle of the same origin as the BCG. In US develops the campaign for Eradication of Bovine Tuberculosis has managed to maintain state territories with very low prevalence and is currently studying the impact of vaccination in cattle in the states with the disease (Lees, 2004).

Epidemiology

The bovine tuberculosis is a disease of high morbidity and mortality. In 1916 caused more deaths in domestic animals than all other infectious diseases combined. Currently the transmission is reduced by the effects of the Eradication Campaign, so that morbidity and mortality have declined significantly.

Agent

Mycobacterium bovis is a bacterium of bacillary form 5 to 7 microns long by 1 to 2 microns wide. It belongs to a group of mycobacterium causing tuberculosis in mammals including humans (Mycobacterium tuberculosis complex). It is classified as acid-resistant because it has a thick cell wall and ceramide-rich and peptide-glycosides (about 60%) that confers some resistance ...