Tuberculosis (TB)
Tuberculosis is caused by infection by the microbe mycobacterium tuberculosis. While this is a condition that was thought to be in decline in the Western world its incidence is rising, with drug-resistant strains appearing, possibly as a result of inadequately treated cases (not because the doctors can’t treat them, but because the patients, many of whom are alcoholics, aren’t good at taking the medication). In the past a major source of infection was milk from infected cattle, causing abdominal TB, but now the usual route is by droplet inhalation from the sputum of an infected individual. The body may respond by producing an inflammatory reaction that walls the infection off - called a primary focus. There may be no symptoms, and while the disease is effectively contained, it lies latent and can be re-activated. There are skin tests - called Mantoux, Heaf and Tine - where protein extracted from the bacterium is injected into the skin: a person with active infection produces a vigorous response after a period of days, indicating the need for treatment. Those who produce no response when screened, and any baby born into a family where a member has TB, are offered vaccination with BCG - which is the Bacille Calmette-Guerin. This is a live TB bacterium which has been weakened, or attenuated, and it confers immunity in about 80% of cases. The infection can be reactivated by any depression of the immune system - treatment with steroids, diseases such as diabetes mellitus, weakness from intercurrent illness in older age. While the reactivation may cause chest problems with cough and blood stained sputum (described in the lung section) there may be associated generalised symptoms with fever, malaise and weight loss, and other parts of the body may be affected such as bone, kidney or brain. Widespread infection, called miliary tuberculosis, causes multiple symptoms and is a severe illness.
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