Tuberculosis
Tuberculosis is caused by infection with Mycobacterium tuberculosis. While this may affect any organ in the body (such as the kidney or the meninges) classically it affects the lungs, which is why we used to have mass screening X-rays to search for cases. It is still amongst the world's leading killers, particularly in the developing world. When it affects the lungs, caught by the inhalation of droplets of saliva from an infected case, initially it produces a swelling (called a tubercle, which is why it is called tuberculosis) in the periphery of the lung. The nearest lymph nodes draining the tubercle will also become infected. Often the patient's own resistance will quell the disease at this stage, leaving what is called a primary focus. Over time, the tubercle and the lymph nodes may calcify.
If our immunity is not good - through malnutrition for example, or immunosuppression treatment - the disease may reawaken. There is fever, night chills, cough producing sputum, possible haemoptysis, and weight loss. The diagnosis is made both by the X-ray appearances and the finding of the bacteria in sputum. Treatments are available using antibiotics, but resistance is emerging in some parts of the world. There is a vaccination available which will convey 80 per cent protection against infection for a number of years.
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