Mycobacterium tuberculosis is a human pathogen that has had a staggering global impact. Its origins are ancient. Spinal deformities typical of those resulting from M. tuberculosis disease have been found in human remains as far apart as Peru and Egypt and dating from at least 5000 BCE . The emergence of M. tuberculosis as a human pathogen is not well understood, but it has been plausibly suggested that the domestication of cattle facilitated close contact to humans, resulting in transmission with eventual evolution of M. bovis, the bovine tuberculosis strain.
Mycobacterium tuberculosis is present worldwide and typically spreads in cramped, overcrowded conditions. There is no evidence that pulmonary TB is more easily transmitted in airplanes or other forms of public transportation. Long-term travellers, those with a weakened immune system or visiting friends and relatives (VFR travellers) in areas where Tuberculosis is endemic are at risk. Humanitarian and healthcare personnel working in communities with active TB are also at increased risk. Persons with active TB should not travel.