Death Spores

You exhale a 30-foot cone of infectious spores. Each creature in the cone must make a Constitution saving throw against disease. If the saving throw fails, the creature takes 6d6 poison damage and becomes poisoned and infected, or it takes half damage and suffers no other effect with a successful save.
Purple-black fungus oozes from the eyes and nose of infected creatures. Any creature touching the infected creature must make a Constitution saving throw or be affected the same as by the initial effect; a successful save means the creature is unaffected.

Only magic that cures diseases can end the effect. If the caster must touch the patient to cast the spell, then the caster is also exposed to the fungus and must make a Constitution saving throw against it.