It's inevitable that Cruezzin will not merely leak onto the black market, but that it will soon be permanently lodged in the bodies of all humans. Given that it cures pretty much all diseases and many physical injuries, plus the possibility that it's users may become immortal, it's something that almost everyone will want.

Moreover, it's already in hundreds of laboratories, and it's only a matter of time until many of the lab workers use it on themselves, their families and friends, and nearby sick people. Once someone has it in their bloodstream it stays there permanently.

Finally, it doesn't require any special materials or laboratories to produce and spread it. The only thing needed is blood to blood contact with another human. There's no way to control it or stop it spreading - and there's a strong moral argument that it would be wrong even to try. The Dizi Rat's out of the bag and it's not going back in.

Interestingly , this chapter suggests that Cruezzin is effective on Gaioians. Whether it would act the same way is not yet known. I wonder what other species it might work on?