Tuberculosis

Tuberculosis, sometimes referred to as TB, is a disease caused by an organism called Mycobacterium tuberculosis.

The TB germ sometimes causes illness soon after the initial exposure, but usually a healthy immune system can prevent disease. If someone is ill because of TB, this is often called active TB. When TB remains in the lungs, but is kept under control by the immune system, this is called latent TB. However, the organisms in the lungs may cause disease years later. This is called reactivation TB.

TB most often affects the lungs, causing symptoms such as a cough lasting for more than three weeks, loss of appetite, weight loss, tiredness, night sweats and fever. The bacteria may spread to other parts of the body, causing other symptoms. TB is a potentially life-threatening condition. Because of HIV’s effect on the immune system, people with HIV are at least seven times more likely than HIV-negative people to develop tuberculosis within the first six months of infection

According to the World Health Organisation’s (WHO) Global TB Report 2009, there were an estimated 48 144 new cases of TB, but Malawi’s National TB Control Programme (NTCP) estimates are around half that. TB case notifications have risen from 5 000 per year in 1985 to more than 25 000 per year. An increase in the number of cases of TB that recur after treatment completion has contributed to this burden. The 2009 WHO report also estimates 68 percent of new TB patients have HIV.

The common turbeculin skin test (TST) is of little diagnostic value for testing for TB in adults in endemic areas like Malawi, but is useful in children. Sputum smear microscopy is the widely available diagnostic test for TB in Malawi but some cases will be missed by this test. A more accurate TB test, a culture of TB bacteria can also be grown in a laboratory. However, this requires specialised and costly equipment and can take six to eight weeks to produce a result and is, therefore, not widely available.

Diagnosis of tuberculosis in the lungs may be made using an X-ray or sputum test, but again, these may not give a clear indication of active TB infection in HIV positive people, because their immune systems are not strong enough to mount an inflammatory reaction against the bacteria. If the necessary facilities are unavailable, then the tuberculosis diagnosis can be based on symptoms.

Active tuberculosis can almost always be cured with a combination of antibiotics. A proper combination of anti-tuberculosis drugs provides both prevention and cure. Effective treatment quickly makes the person with tuberculosis non-contagious and, therefore, prevents further spread of tuberculosis. Achieving a cure for TB takes about six to eight months of daily treatment. Several drugs are needed to treat active Tuberculosis and these can include Isoniazid, Rifampin, Ethambutol, Pyrazinamide.

For HIV-negative people, there is a live vaccine against TB known as the BCG vaccine, although its effectiveness appears to vary in different populations. It should not be given to people with HIV, because there is a small chance that it might cause a TB-like illness.

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