INTRODUCTION : Acharya charaka has quoted ‘Janapadodwansa’ which means   ‘janapada’- refers to group of people living in specific location, ‘udwansa’- destruction. In modern science it is called epidemics. The reason for such destruction is dushita vayu(air borne-TB,small pox, etc) dushita jala (water borne- Covid 19, Typhoid,Cholera,Hepatitis etc), dushita kala (Swineflu etc), dushita desha(Ebola in west Africa, Gorakhpur Japanese elephantiasis in India etc & pandemics like zika, AIDS). Acharya susrutha incorporated such diseases under oupasargika rogas. The reasons for such calamities are inevitable disastrous factors. Aniyata hetus (harmful effects of sun,moon, stars,planets such as floods,cyclones,land slides,earth quakes,tsunamis etc),prajnaparadha ( intake of asatmya ahara, terrorism,wars, accidents etc) sastra prabhava ( missiles etc); abhisyandha (effect of pathogen) and abhisapa(curses) result in to spread of epidemics. Whenever changes occur in enviro...