Tuberculosis (TB)

Part I (Lung TB)

Tuberculosis is a worldwide disease. It was equally found in the western developed world until a century back. Better treatment, hygiene, case detection, prevention has decreased the incidence in the developed world. It is a common cause of prolonged illness and fatalities in the 3rd world. HIV had caused spread and increase in no of TB patients which are now declining.

It is caused by a bacteria (Mycobacterium) which grows better in tissues with high Oxygen levels. Since oxygen levels are high in the upper portion of lungs, the commonest form of TB involves upper lungs.

It is spread by droplet infection. Droplets are small drops of body fluid sent out of the body during coughing and sneezing. The TB bacteria are present in the phlegm of patients and is spread in patients vicinity when they cough. Once it is inhaled by susceptible people, the infection may occur.

Susceptible persons are ones with decreased or low immunity. These include young children, elderly patients, those who have not been immunised with BCG, cancer patients, transplant recipients, diabetics, HIV patients, other debilitating illnesses like cirrhosis liver, chronic kidney disease etc.

Primary tuberculosis: The initial infection after the mycobacterium is inhaled, has been studied in Norway in about 500 new tuberculin converters.

It manifests usually as fever of 2 to 3 weeks, cough, tiredness and occasionally chest pain.

Inv in primary tuberculosis show: enlargement of lymph nodes in hilar areas of lungs, pneumonia or effusion at times on chest X-Ray. Skin tuberculin test is +ve. Most of these patients recover (90%). However, in some cases it may spread to other organs including brain, bones, kidneys, intestines etc. Spread is more likely in HIV sufferers or other low immune states.

Reactivation tuberculosis:

After a gap of few years to at times few decades, when the body immunity is low, the common form seen in adults takes shape. It can be symptom-free for 2-3 yrs and then cause disablement.

In the chest, upper lobe areas are involved more often. These may initially be like pneumonia but later cavities may appear.

Common symptoms are fever, weight loss, poor appetite, fatigue and cough. About ¼ may have blood in phlegm. Fever is maximum in the evenings and night and drenching sweats are seen in ½ the patients. Phlegm may be initially scanty but later green or yellow and copious. If untreated lung may be destroyed.

X-Ray is usually the 1st clue for diagnosis. Normal X Rays can be seen rarely and then CT may show lung lesions. Tuberculin test is +ve, bacteria may be seen in sputum(phlegm) and can be grown in culture. Hemoglobin, albumin and serum sodium may be low while CRP and globulins are usually high. Antibodies specifically against TB are found in the blood.

Complications of TB:

Complications are in the form of massive bleeding, bronchiectasis, spread to other organs, pneumothorax (air in the pleural cavity) and sometimes cancer of the lungs.