TUBERCULOSIS

Tuberculosis, often called TB, is a chronic bacterial infection. It can develop after a person inhales droplets sprayed into the air (as from a cough or sneeze) by someone infected with Mycobacterium tuberculosis. Good ventilation and exposure to sunlight decrease the risk of exposure.

If a person is exposed to the TB bacterium, the organism may gain entry to the lungs. If a person is infected, usually no symptoms (cough that produces discolored or bloody sputum, pain with breathing or coughing, and pain in the spine or large joints, fatigue, and night sweats) are apparent initially, although there may be a mild cough and slight fever. Sometimes tuberculosis develops within weeks after the initial exposure. More often, the TB organism may lie dormant for many years before the disease becomes apparent. The disease may be reactivated under conditions in which the immune system is weakened, including old age, malnutrition, alcoholism, immunosuppressive therapy, or certain illnesses such as AIDS or malignancies of the lymph or blood system.

The spread of disease generally is limited by lymph nodes. The TB organism can spread through the lymph nodes and blood to almost any organ in the body. The areas affected include the lining of the lungs, the bones of the spine or large joints, and kidneys.

The preliminary diagnosis of TB is based on review of the chest X-ray. Usually within 2 to 3 months after the initial infection, a spot may be noticeable on an X-ray of the chest. This spot persists indefinitely and usually is no cause for concern. The tuberculin skin test converts from negative to positive at this time.

In addition to the chest X-ray, the physician may obtain a sample of material from the sputum for staining and examination under the microscope.

In the past, sanitariums often were used for persons who had active TB. In recent years, modern drugs are used for treatment of this disease. The drug regimens often include combined use of isoniazid and rifampin, although other combinations also can be used.