Specifically, the disease known as the plague; hence, any contagious or infectious epidemic disease that is virulent and devastating.

any epidemic disease with a high death rate

an epidemic or even a pandemic of a virulent and highly contagious disease

Fig.: That which is pestilent, noxious, or pernicious to the moral character of great numbers.

a pernicious evil influence

Adds 50 Poison Damage for 5 seconds