It is estimated that at least one third of the human population is infected with this disease at any time. It can affect many different areas of the body including the chest, skin, bones, kidneys and brain. Approximately eight million new cases occur each year with over 3 million deaths attributed to this illness. It has been guessed that one human infection occurs each second and that any individual infected with untreated pulmonary infection (the so called ‘open case’) can infect up to 10 others.
Unprotected exposure causes the typical pulmonary infection but the disease can also affect other parts of the body either through swallowing infected saliva or via infected dairy products e.g. milk. The normal incubation period is between 4 to 12 weeks after exposure.
The classical triad of weight loss, night sweats and cough is often seen in many of the developing countries. However patients may also present with symptoms associated with the infection of other organs e.g. kidney, brain, bone or skin. The initial exposure to infection with tuberculosis may not cause any serious symptoms and the disease may be ‘enclosed’ by body defences at that time. However, with the onset of any immunodeficiency disorder (eg AIDS, Leukaemia, Steroid usage etc) this personal protection may become deficient and the disease may reactivate and lead to the standard symptoms.
Even though this disease is found in every country throughout the world the main incidence is in the developing parts of our world. It is estimated that over 90% of the world’s tuberculosis is confined to Africa, Central and South America, and Asia. Significant disease outbreaks also occur in some of the island countries.
The disease is mainly transmitted through the respiratory route with direct infection occurring to those exposed but without personal protection.
Chemotherapy for this disease is changing as resistance to the classical drugs is growing at an alarming rate. The prolonged course of treatment required is a major disincentive for many to complete their course and so recent regimes are evaluating much shorter intensive courses.
A single BCG vaccination at childhood gives good protection against TB meningitis and less against pulmonary TB and is part of many countries’ childhood vaccination programmes.