UGC NET Paper 1 GA 20 Nov 2021 Shift 1 Solved Paper

The rapid spread of disease to a large number of hosts in a given population over a short period of time is referred to as an epidemic Infectious disease epidemics are typically caused by a change in the ecology of the host population, a genetic change in the pathogen reservoir, or the introduction of an emerging pathogen into a host population.
In general, an epidemic occurs when host immunity to an established pathogen or a newly emerging novel pathogen is suddenly reduced below the endemic equilibrium and the transmission threshold is exceeded.