Pestilence

8th-level necromancy
Casting Time: 1 action
Range: Touch
Components: V, S, M (a sample of diseased tissue)
Duration: Instantaneous
Book of Vile Darkness

You touch a creature and infect them with a disease. The creature makes a Constitution saving throw or contracts whatever illness your sample contains. The target suffers none of the disease effects, but becomes contagious to others after 24 hours.