Infections are little and lightweight. They can coast through the air, get by in water, or even on the outside of your skin. Infections can be passed starting with one individual then onto the next by shaking hands, contacting food, through water, or through the air when an individual hacks or sniffles.
Infections spread from individual to individual mostly in beads that fly out when you hack or wheeze. These small drops from a wiped out individual travel through the air and land on the mouths or noses of others close by.