The Plague Bearer's disease is lethal and highly contagious. Their desire is to kill off all other players.

The Plague Bearer starts the game with rodents that carry the plague. They have one rodent for every five players in the game (rounded). If there are several Plague Bearers then they know each other and their rodent counts are combined. Each Plague Bearer may use one rodent per night. Each night, the Plague Bearer may free one of their rodents to contaminate another player. Contaminated players will be affected by the disease. The Plague Bearer cannot be contaminated. If the Plague Bearer attempts to contaminate an already contaminated player, they are informed, but the rodent is still used up. Contaminating a player is an immediate ability. Any player who visits or is visited by a contaminated player immediately becomes contaminated themselves. All types of action (target, attack, investigation, etc) are considered visits. At the start of the second night after being contaminated, the player is informed that they are contaminated.

At the end of the second night after being contaminated, the player will die. This is not an attack. Should the player still be alive afterwards, they remain contaminated, but will not die due to being contaminated again. If no members of the plague team or channel remain, all players stop being contaminated: they are not informed of this. If the Plague Bearer attempts to use a rodent on the Plague Doctor, the attempt fails, the Plague Doctor immediately dies (this is not an attack), and the rodent is not used up.