[Kromm]

Nitpickers should note that "disease" and "infection" are terms of art in GURPS. Disease is a big heading covering pp. B442-444, and Infection is another one on p. B444. They have specific meanings in the game. The super-category that encompasses these and more is found on p. B442: Illness. The spell isn't called "Cure Illness."

All of which said, I detest nitpicking. Cure Disease should cure whatever the setting's experts in disease believe a spell for curing disease should cure. The wizards among those experts are the ones who came up with the spell, after all!

If the experts are TL0 shamans, then the spell cures any malaise caused by an evil spirit or pestilent object. If they're TL2, change the belief to humors and miasmas. If they're TL12 techno-mages, then it cures anything that endpoint medical science has conclusively attributed to bacteria, fungi, parasites, prions, viroids, viruses, or any new class of infectious agent discovered (I'd propose "wet nanomachines," since the difference from the previous list is one of origin, not mechanism of action) . . . which will include a lot of things that we TL8 types don't believe are caused by infection, because as has been pointed out, more and more things are reattributed to infectious agents each year. At any TL, if there's magic to cure disease, then there's probably magic to cause it, so whatever that relies on – spirits, warped mana, etc. – Cure Disease should work on that as well.

"Believe" is fair here because Cure Disease is not Cure Disease/TL. It isn't meant to have hard technological or scientific criteria. It's classic folk magic – the sort that precedes the scientific method by four or five TLs. While "magic is a science" is a way to see things, it's probably the wrong way to see things prior to TL5 . . . which is uncoincidentally when widespread belief in magic started to wane rapidly. The GURPS magic system has been fairly random, with risk of summoning demons and many things that work a certain way by fiat, since Steve designed it in the mid-1980s; it has never been scientific.