Tuberculosis, commonly known as TB, is a bacterial infection caused by a germ called Mycobacterium tuberculosis. It is an airborne infection which means that an infected person spreads the disease by coughing, sneezing, spitting, singing and other respiratory actions. These actions generate infected droplets, which are dispersed throughout space without settling, and the organisms that they contain can remain viable for long periods of time.
Which organs are affected with TB?
Tuberculosis mainly affects the lungs, which is called Pulmonary Tuberculosis, but it can affect any organ in the body including bones, brain, intestines, lymph nodes, skin, serous membranes surrounding organs like pleura and peritoneum. Sometimes when a person’s immunity is very low it can even spread through blood to cause widespread distribution in many organs which is known as Miliary Tuberculosis.
How common is TB in India and globally?
According to WHO global TB report 2010, India has the highest incidence of TB, accounting for one fifth (21 percent) of the global incidence (Global annual incidence estimate is 9.4 million cases, out of which an estimated 2 million cases are from India). Amazingly almost 32 per cent of world population is infected with TB as judged by positive tuberculin test.
When should TB be suspected?
Pulmonary or Lung TB should be suspected if a person has cough for three weeks or more. Other symptoms of Pulmonary TB are:
- Fever, especially rising in the evening
- Pain in the chest
- Loss of weight
- Loss of appetite
- Coughing up of blood
Extra Pulmonary Tuberculosis (TB of any other organ other than lung) should be suspected when symptoms specific to that organ are present chronically like bowel disturbances in abdominal TB, sinus formation in bone TB, chronic headache and neurological deficits in brain TB.
How is TB diagnosed?
- Initially most patients need to get a chest X-ray which may show shadows suggestive of TB.
- Sputum examination for TB bacteria (Acid Fast Bacilli) is done for three days to confirm it.
- Needle aspiration of the lymph node may also confirm the diagnosis in case that is the presenting symptom.
- Sometimes a CT scan of chest and Bronchoscopy for washings is needed, if there is cough with no sputum production.
Tests like QuantiFERON®-TB Gold and Elisa for TB are not useful in a country like ours where TB is rampant.
How is TB treated?
- TB is treated with a combination of four drugs (rifapicin, isiniazide, pyrazinamide and ethambutol) for 2-3 months in the induction phase and with two drugs (rifapicin and isoniazide) for 4-6 months in the continuation phase.
- Priority should be given to bringing all patients under directly observed therapy (DOTS). This results in a 100 per cent cure rate and limits the relapse rate to no more than 3.5 percent of the susceptible cases.
- Drug resistance (multi drug resistance MDR-TB and XDR-TB) are becoming more frequent and should be actively looked for. Drug resistance is a man-made phenomenon mainly due to poor compliance with treatment. MDR-TB is much more difficult to treat and requires intensive monitoring through experts.
- Sputum positive patients remain infective for at least 2 weeks of effective chemotherapy and may require being isolated.
Preventive therapy for TB
- BCG vaccination at birth prevents major episodes of TB in children and is mandatory in India. It should be offered to anybody who is tuberculin negative.
- It is very difficult to prevent tubercle bacilli from entering our body but a strong immune system will not allow the bacteria to multiply in our body and will remain latent.
- Lead a healthy lifestyle with optimum amount of exercise.
- Try and avoid crowded places especially when you are not well.
- Isolate an infected person till they are bacteriologically negative.
The role of a balanced diet with plenty of fresh fruits and vegetables is always important, but if you suffer from TB, it is absolutely essential to undergo regular treatment. Consult a doctor if you suspect any of the symptoms of TB to receive proper treatment.