Tuberculosis still exists, and many people die from it. Tuberculosis is a chronic disease caused by the BK virus. There are types of tuberculosis that infect humans, and others that infect cattle. The lungs are the organ most often affected by this disease. Tuberculosis is transmitted by droplets containing bacteria, coughed up by sufferers. The incubation period in humans is 4 to 12 weeks. Hygiene and health" program on Radio Don Bosco.