Vegan choriomeningitis

From Memory Alpha, the free Star Trek reference

Vegan choriomeningitis is a disease with which volunteers from Gideon were deliberately infected. The Gideons were virtually immortal; their goal was to introduce death back into their critically overpopulated and germ-free society. The microbes used by the Gideons to infect their world were taken from the blood of Captain James T. Kirk. (TOS: "The Mark of Gideon")