What It Is
Tuberculosis (TB) is a contagious disease. Tuberculosis was earlier known as ‘consumption’. Its symptoms include chest pain, coughing up blood and a productive, prolonged cough for more than three weeks. Its systematic symptoms include fever, chills, night sweats, appetite loss, weight loss, pallor, and often a tendency to fatigue very easily. When the disease becomes active, 75% of the cases are pulmonary TB. In the other 25% of active cases, the infection moves from the lungs, causing other kinds of TB more common in young children. The primary cause of TB, Mycobacterium Tuberculosis, is an aerobic bacterium that divides every 16 to 20 hours, an extremely slow rate compared with other bacteria, which usually divide in less than an hour.
Transmission and Diagnosis
When people suffering from active pulmonary TB cough, sneeze, speak, or spit, they expel infectious aerosol droplets 0.5 to 5 mm in diameter. A single sneeze, for instance, can release up to 40,000 droplets. Each one of these droplets may transmit the disease, since the infectious dose of tuberculosis is very low and the inhalation of just a single bacterium can cause a new infection.
Tuberculosis can be a difficult disease to diagnose, mainly due to the difficulty in culturing this slow-growing organism in the laboratory (4–12 weeks for blood culture). A complete medical evaluation for TB must include a medical history, a chest X-ray, and a physical examination. Tuberculosis radiology is used in the diagnosis of TB. It may also include a tuberculin skin test, a serological test, microbiological smears and cultures. The interpretation of the tuberculin skin test depends upon the person’s risk factors for infection and progression to TB disease, such as exposure to other cases of TB or immunosuppression.
TB prevention and control takes two parallel approaches. In the first, people with TB and their contacts are identified and then treated. Identification of infections often involves testing high-risk groups for TB. In the second approach, children are vaccinated to protect them from TB. Unfortunately, no vaccine is available that provides reliable protection for adults. However, in tropical areas where the levels of other species of mycobacteria are high, exposure to nontuberculous mycobacteria gives some protection against TB.
Treatment for TB uses antibiotics to kill the bacteria. The two antibiotics most commonly used are rifampicin and isoniazid. However, instead of the short course of antibiotics typically used to cure other bacterial infections, TB requires much longer periods of treatment (around 6 to 12 months) to entirely eliminate mycobacteria from the body.