Plaguebearer

Every night you have the ability to infect a person with the plague. If players with the plague visit other people then they get infected them too.

Basic Mechanics
If a person with the plague is visited then by an uninfected person, they will get the plague. For example: Doctor with the plague visited cop. Cop got the plague and proceeds to check other people infected them. The plague has no affect on the people who have it. However if every member of the town gets the plague a message will be revealed to the whole town. When this happens, the Plaguebearer converts into Pestilence.

Advanced Mechanics
Roles that visit multiple people in a single night like the Bus Driver or the Transporter will allow you to spread your plague incredibly quick. If a Retributionist or a Necromancer attempts to raise an infected dead person, they too will be infected.

Trivia

 * It is possible for you to turn into Pestilence without even visiting anyone.