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. Contaminated players are contagious, and remain so till their death. Any player who visits or is visited by a contagious player is immediately contaminated. Any type of action (target, attack, investigation, etc) is counted as a visit. 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 stop being contagious and die. This is not an attack. Should the player still be alive afterwards, they remain contagious, but will not die again. If no members of the plague team or channel remain, all players are no longer contaminated, although they are not informed about this. If the Plague Bearer attempts to use a rodent on the Plague Doctor, the attempt fails, the Plague Doctor immediately dies (not an attack), and the rodent is not used up. The Plague Bearer cannot win while a Plague Doctor is alive.