There are multiple roles available for Infected Humans.

The Infected are zombie-like humans who are incapable of rational thought.  They wander the streets with only one thought in mind - to find food.  Due to an alteration in their sense of smell, the Infected prefer meat from those who are not carrying the disease, so they will hunt down animals and uninfected humans alike whenever possible.

The Infected Humans are not paid roles, but successful actors will be credited in the show as being part of the cast.