Tuberculosis (TB) is an infectious disease caused mainly by the bacteria Mycobacterium.tuberculosis ( M.tb )
that typically affects the lungs (pulmonary TB), but may also affect other organs (extrapulmonary TB) also.Robert Koch, a German physician and scientist, presented his discovery of Mycobacterium tuberculosis
, on the evening of March 24, 1882.he described their appearance under the microscope . Mycobacterium tuberculosis is a fairly large nonmotile rod-shaped bacterium
distantly related to the Actinomycetes.It is an obligate aerobe
. For this reason, in the classic case of tuberculosis, the M.TB. complexes are always found in the well-aerated upper lobes of the lungs.It has a slow generation time, 15-20 hours.Tuberculosis is spread through air droplets which are expelled when persons with infectious TB disease cough, sneeze, speak, or sing. Close contacts (persons with prolonged, frequent, or intense contact) are at highest risk of becoming infected.TB in the lungs or throat can be infectious. This means that the bacteria can be spread to other people. TB in other parts of the body, such as the kidney or spine, is usually not infectious.The primary stage of the tuberculosis may be symptom-free, or the individual may experience a flu-like illness. In the secondary stage, called active disease, there might be a slight fever, night sweats, weight loss, fatigue and various other symptoms, depending on the part of the body affected. Tuberculosis of the lung is usually associated with a dry cough that eventually leads to a productive cough with blood-stained sputum. There might also be chest pain and shortness of breath. A complete medical evaluation for tuberculosis includes a medical history, a physical examination, a tuberculin skin test, a chest X-ray, and microbiologic smears and cultures.Latent tuberculosis infection can be detected with a tuberculosis skin test, the test involves injecting a small amount of testing fluid (called tuberculin) just under the skin on the lower part of the arm.
After two or three days, the reaction to the testing fluid will be measured. If there is a small bump where the tuberculin was injected, it will be measured to find out if the test reaction is positive or negative. A positive reaction usually indicates a latent tuberculosis infection.The diganosis of tuberculosis requires detection of acid-fast bacilli
in sputum via the Ziehl-Neelsen
method as previously described. In both human and economic terms, the prevention of tuberculosis is preferable to treatment, which highlights the importance of developing of a safe and effective vaccine. The Bacillus of Calmette and Guerin (BCG)
vaccine is useful in preventing certain types of tuberculosis, although its efficacy is variable. No vaccine yet exists that is truly effective against adult forms of the disease. Therefore, it will be important to identify the immune mechanisms and antigens necessary to protect against tuberculosis infection to make a significant, worldwide impact on the disease.the infected individuals are treated with a combination of various antituberculosis drugs such as rifampin, pyrazinamide, and ethambutol. Tuberculosis drugs have to be taken regularly, typically for 6 to 12 months. Many patients abandon their treatment when they feel better; similarly, preventive treatment is often abandoned because of the inconvenience. Such noncompliance is believed to be the main reason for the upsurge
in drug-resistant strains of the tuberculosis bacilli, many of which are resistant to more than one drug. Drug-resistant tuberculosis is difficult to treat and has a much higher death rate.