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Tuberculosis

An infectious disease caused by the tubercle bacillus This bacterium was discovered by Robert Koch in 1882 and identified as being the causative agent of TB. Tuberculosis was formerly regarded as a manifestation of extreme physical decline as a result of malnutrition, poor hygiene and poverty, and it was known as (galloping) consumption or phthisis because of the considerable emaciation it caused. The name tuberculosis arose in the nineteenth century after the characteristic inflammatory tubercles, which were found in the organs of deceased patients. Hereditary factors, physical condition, diet, race and age are factors contributing to a person’s susceptibility to the disease and the course taken by it. Most patients are between 18 and 30 years old. After contact with a patient in whom TB is active, infection takes place via the air passages and causes a reaction by way of inflammation in a piece of lung tissue. Local lymph glands in the adjoining lung hilum (this is the point where blood vessels, nerves and bronchi enter the lung) are usually affected too. When lymph glands become affected, the main centre of infection is called the primary complex. The body is usually able to halt the infection. The primary centre of infection forms a scar and is encapsulated by the laying down of calcium. This calcium deposit can be seen on an X-ray of the lungs. The patient has then recovered and has either not noticed the infection at all or has shown only slight symptoms such as tiredness, slight fever in the evening, and perspiration at night. If, because of reduced resistance for example, the patient’s body is unable to keep the infection in check, bacteria can remain behind in the encapsulated centre of infection and cause a postprimary infection after being reactivated. Renewed infection from outside can also lead to the spreading of this process. Active post-primary infection now becomes clearly apparent, with a general feeling of illness, increase in temperature in the evening, coughing with or without sputum, sweating at night and considerable emaciation. Active tuberculosis acquires a chronic character and leads to the death of lung tissue and to the creation of inflamed cells which have a homogenous cheeselike appearance. These cheese-like masses can, if they move, enter the bronchi, causing open tuberculosis, with cavities remaining in the lungs. The patient now has cavity tuberculosis, and this is extremely contagious, because the cheese-like masses contain large amounts of bacteria and are coughed up. Other parts of the lung are infected during this coughing, and the swallowing of sputum leads to intestinal tuberculosis. The pleural membranes around the lung are usually affected too. Blood vessels at the centres of infection are eroded, causing blood to be coughed up (haemoptysis) and bacilli spread to many other organs and tissues, such as bones, brain, kidneys, adrenal glands, sexual organs and lymph glands, which in turn become infected. If this spread of infection progresses rapidly, the condition is known as miliary tuberculosis. The patient is then very ill, has a high temperature, and has, in all his organs, tubercles of the size of a barleycorn (milium means millet in Latin). Infection can also be transmitted by means of unpasteurized cow’s milk. The tubercle bacillus in cow’s milk {Myobacterium tuberculosis bovis) causes intestinal tuberculosis, and differs from the bacillus which usually causes tuberculosis in humans {Mycobacterium tuberculosis ho minis). However, milk has been pasteurized from the 1940s onwards, and livestock has been free of tuberculosis since 1970, so that this form of tuberculosis has become extremely rare. Tuberculosis is diagnosed in various ways. The most conclusive method is to demonstrate the presence of the bacillus in sputum. With the aid of a special stain (Ziehl-Neelsen), the bacilli appear under the microscope as slender red rods. In addition to this, an X-ray of the lungs is also essential. Large groups can be examined by injecting tuberculin (purified proteins from dead bacilli) into the skin. This is the so-called Mantoux test. If humans are infected they will, after 4-6 weeks, have sufficient antibodies in their blood to show a positive skin reaction. As a result of improved diagnostics, the setting-up of health centres, and new drugs, deaths

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