I haven't found anything official for 5E, not about players being infected. Usually, the rule is that while being the animal they are NPCs out of their control and in the GM hands... that sucks.<br/><br/>It was in 3.x where there were rules for lycanthrope characters.<br/><br/>This is an example (http://www.tribality.com/2015/11/13/werewolf-prestige-class-for-dd-5e/) of Lycanthropy as a prestige class but is homebrew.