So... Papa Nurgle is now conver- I mean hiring nurses. Why not?
Nurgle "hiring" nurses to look after his flock makes sense, nobody cares as much about their worshipers as Papa Nurgle does. He wants everyone in his "family" to live long, happy lives free of pain, sorrow and misery. Of course, there's also the fact that he does this by turning them into festering, maggot-filled walking corpses that spread disease and decay wherever they go, but why look a (demonic) gift horse in the mouth? Sure, your skin is falling off and your guts are home to a hundred brand new species of deadly bacteria, but at least you're happy about it!