Tuberculosis
Tuberculosis Before it was even discovered in 1882 by Robert Koch, tuberculosis was responsible for almost one-seventh of all the deaths in Europe. Approximately eight million new tuberculosis cases occur every year, making it the most common infectious cause of death in adults worldwide. ... Tuberculosis is an infection that is caused by Mycobacterium tuberculosis. ... It is classified as either latent, where the infection occurs when tuberculosis-causing bacteria are in the body but there are no signs or symptoms, or active, where tuberculosis is found in the body and there are signs or symptoms of tuberculosis. ... Tuberculosis is spread from person to person through the air by droplet nuclei, which are produced when persons with pulmonary or laryngeal tuberculosis cough, sneeze, speak, or sing. ... The classification of persons exposed to or infected with Mycobacterium tuberculosis is intended mainly as an operational structure for public health programs. ... The first class is “no tuberculosis exposure, not infected,” where the persons have no history of exposure and a negative reaction to the tuberculin skin test. The second class is “Tuberculosis exposure, not evidence of infection,” where the persons have a history of exposure but have a negative reaction to the tuberculin skin test. The third class is “Latent tuberculosis infection, no disease,” where the persons have a positive reaction to the tuberculin skin test, negative bacteriologic studies, and not clinical, bacteriological, or radiographic evidence of active tuberculosis. The fourth class is “Tuberculosis: clinically active,” where all patients with clinically active tuberculosis whose diagnostic procedures are complete. The next class is “Tuberculosis: not clinically active,” which is defined by a history of previous episodes of tuberculosis or abnormal stable radiographic findings in a person with a positive reaction to tuberculin skin test, negative bacteriologic studies, and no clinical and/or radiographic evidence of current disease.