📖 In the developed world, life expectancy has increased substantially during the last century. Deaths due to infectious diseases also declined in these countries whereas deaths due to cancer and other cardiovascular diseases increased. With the rising socio-economic status, similar health transition is occurring in some of the developing countries. In India, though infectious diseases continue to be a public health problem but an increase in the occurrence of non-communicable diseases has also been noted particularly in urban areas and in economically advanced states.