(a) Tuberculosis: It is an infectious disease caused by the bacterium Mycobacterium tuberculosis. This bacterium secretes a toxin called tuberculin and infects parts of the body such as limbs, lymph glands and bones. Symptoms of the disease include sickness, loss of appetite and weight, fever and night sweats.

There are two specific sites of tuberculosis infection:

(i) Lung or pulmonary TB: In this, the person suffers from fever and cough and produces blood-stained sputum. It may even destroy large areas of the lungs.

(ii) Lymph gland TB: It is characterised by the swelling and tenderness of the lymph glands, often in the legs. It can be prevented by immunisation with BCG (Bacillus Calmette‒Guerin), which gives immunity for 3‒5 years.

Tuberculosis can be cured by six essential drugs: rifampicin, INH, streptomycin, pyrazinamide, ethambutol and thioacetozone.

(b) Polio: It is a disease of the nervous system caused by polio virus. The virus enters the body via food and water and destroys motor nerve cells of the spinal cord responsible for muscle control. Hence, the muscles of a person suffering from polio cannot carry out normal functions.

The disease is characterised by fever, vomiting, muscular pain and tingling sensation in limbs; these ultimately lead to paralysis.

Polio can be prevented by giving a child oral polio vaccine (OPV), which provides immunity against the polio virus.

Children below the age of five are given OPV on specific days, all over the country. Such days are known as national immunisation days (NIDS).