As they have to infect everyone and THEN kill them, it's a quiet hard role.
To make it a bit easier,
When plague bearer spawns, everyone has that health bar like as for demon which only can be seen by them. If Plague bearer infects someone, they have to vent in order to decrease the infected one's health. It could be decided by host how much health will decrease by 1 vent (could be on 10 to 30% health bar dec)
Also, We can have a cd on vent too.
