because a person is a person
yes Ever heard of Hannibal the cannibal?
By coughing on other people and spreading germs. Even coughing into your hands can spread disease. That hand you coughed into may open a door 5 minutes later and be touched by someone else who may...
When a disease can be moved from person it can be known as an Infectious disease, a Transmittable disease, or a communicable disease.
Bat man vs. Joker