Other mycobacteria that cause human diseases are very rare in people with healthy immune systems. Tuberculosis in humans is commonly seen as a lung infection or pneumonia. While infection of other organs such as the brain, bones, intestines, and kidneys also occurs, these are rare. Humans get infected by M. tuberculosis when they inhale the mycobacterium. This usually occurs when someone with active tuberculosis of the lungs coughs, causing the release of thousands of bacteria into the air around them.
People breathing the same air for prolonged periods are likely to inhale the bacteria.
Thus, most people who get infected have close contact with the infectious person, i.e., live in the same house. Tuberculosis is not transmitted by a foodborne route. Meat inspectors working with infected animals are not at increased risk for tuberculosis. Patients with tuberculosis of the lungs have a prolonged illness with fever, cough, night-sweats, weight loss and may occasionally cough up blood. As the disease progresses, symptoms get worse and shortness of breath ensues.