An emerging infectious disease (EID) refer to infectious diseases that have either newly appeared in a population or have existed but are rapidly increasing in incidence, geographic range, or severity due to factors such as environmental changes, antimicrobial resistance, and human-animal interactions. The minority that are capable of developing efficient transmission between humans can become major public and global concerns as potential causes of epidemics or pandemics. Their many impacts can be economic and societal, as well as clinical. EIDs have been increasing steadily since at least 1940.