Mycobacteria are found in habitats such as water or soil. However, a few are intracellular pathogens of animals and humans. Mycobacterium tuberculosis, along with M. bovis, M. africanum, and M. microti all cause the disease known as tuberculosis (TB) and are members of the tuberculosis species complex. Each member of the TB complex is pathogenic, but M. tuberculosis is pathogenic for humans while M. bovis is usually pathogenic for animals.
M. bovis was causing TB in the animal kingdom long before invading humans. However, after the domestication of cattle between 8000-4000 BC, there is archaeological evidence of human infection by M. bovis probably through milk consumption. M. tuberculosis is probably a human-specialized form of M. bovis developed among milk-drinking Indo-Europeans who then spread the disease during their migration into western Europe and Eurasia. By 1000 BC, M. tuberculosis and pulmonary TB had spread throughout the known world.
No comments:
Post a Comment