Phthiriasis is slow. I mean, really slow. He can't even catch a cold.

The best he's managed is a collection of lice.

Just like orks - i.e. stupid and ugly - Bloodbowl is the best place for him. Hopefully someone will stamp this failure of a plague-spreading monstrosity into a greasy smear, increasing the fearsomeness of the Plague Lord's minions by an order of magnitude.