WHO or World Health Organization performs three vital roles in combating diseases are as follows: (i) To fight against diseases throughout the world and to prevent their spread at the source. (ii) It has launched a programme along with UNICEF to immunize children against six major diseases like Measles, Diphtheria, Tetanus, Tuberculosis, Polio and Whooping Cough. (iii) To set international standards for food, water, biological and pharmaceutical production such as Drugs, Medicines and Vaccines.