Tuberculosis also known as TB is a common infectious disease which can affect several organs of the body and is caused by the bacteria Mycobacterium tuberculosis. Tuberculosis most commonly occurs in the lungs. The disease is airborne and spreads from infective persons to other non infected persons through when the infected person coughs, sneezes and through transmission of respiratory secretions in the environment.
In most of the infected persons tuberculosis does not produce any evident symptom rather the disease remains in latent form. Every one patient out of the ten latent cases of tuberculosis will show symptoms of active disease and about 50% of these patients will die eventually without any treatment.
The most common symptoms of tuberculosis include chronic cough with production of sputum usually blood tinged, fever, episodes of night sweat, unintentional loss of body weight etc. Other than respiratory tract related symptoms tuberculosis may lead to wide variety of specific symptoms depending upon the organ involved.
Tuberculosis is one of the most common infectious diseases worldwide as about one third of the total population of the world is estimated to have tuberculosis infection (both latent and active). The incidence of new infection is about 1% of the total world population. About 80% of the total population of Asia and Africa show positive test result following tuberculin test indicating presence of tuberculosis infection (which could be latent without any evident symptoms).
The incidence of tuberculosis infection was quite low in the developed countries in comparison to the developing countries however the incidence of tuberculosis increases in the developed countries especially due to emergence of HIV infections after 1985. HIV/AIDS leads to crippling of the immune system of the body which provides the primary defense against active tuberculosis disease. The incidence of tuberculosis has somewhat decreased following use of the stronger and newer antibiotic drugs following 1993 although it still remains concern.
Symptoms
Tuberculosis can affect different organs of the body; mainly the lungs. Lung tuberculosis is known as pulmonary tuberculosis whereas tuberculosis infection to other organs is known as extrapulmonary tuberculoiss. In some patients both the pulmonary and the extrapulmonary tuberculosis infection may occur at the same time.
Symptoms of tuberculosis can be classified under two headings; general symptoms and specific symptoms depending upon the organ involved.
General symptoms include fever with chill, episodes of night sweat, lack of appetite, unintentional weight loss, extreme tiredness etc.
Specific symptoms can be again of two types; pulmonary and extrapulmonary.
Pulmonary tuberculosis is very common; in about 90% of the active cases of tuberculosis lung involvement occurs. Common symptoms indicating lung involvement include episodes of cough with sputum production, blood tinged cough, chest pain etc. In about 25% of the cases of pulmonary tuberculosis there may not be any presenting symptom. In some cases the infection may spread to the pulmonary artery and leads to severe degree of bleeding (known as Rasmussen’s aneurysm). Mainly the upper part of the lungs (the apex) is affected by tuberculosis either due to better air flow (as tuberculosis is an airborne disease) or poor drainage through lymphatic channels. Prolonged infection of tuberculosis at the upper part of the lungs may lead to scaring of the lung and impairment of lung function.
In about 15 to 20% of the active cases of tuberculosis involvement of other organs may occurs leading to extrapulmonary tuberculosis. Extrapulmonary tuberculosis usually occurs in children and people with poor immunity as in people suffering from HIV/AIDS. The commonly affected extrapulmonary organs include the pleura, central nervous system, bones and joints, genitourinary system etc. In some people with extremely poor immune function a widespread variety of extrapulmonary tuberculosis may emerge. This condition is known as miliary tuberculosis and affects about 10% of the patients suffering from extrapulmonary tuberculosis.
Symptoms specific to particular organ or systems include
1. Bone and joints: bone pain, stiffness, restricted movement of the affected joints mainly the hip and knee joints  are the common presenting symptoms. Often extrapulmonary  tuberculosis may affect the vertebral bones forming the spine (Pott’s tuberculosis) leading to back pain, stiffness of back, several symptoms due to compression of the adjacent nerves like inability to control bowel and bladder activities, weakness to frank paralysis of lower limbs, loss of sensation etc.
2. Meninges (the protective cover of the brain and the spinal cord): sometimes tuberculosis may lead to inflammation of the meninges leading tubercular meningitis characterized by high fever, excruciating headache, confusion, drowsiness, stiffness of neck etc.
3. Impairment of liver and kidney functions due to tuberculosis
4. Involvement of the heart leading to inflammatory damage to the heart muscles, hear valves collection of fluids in the area surrounding the heart etc.