I'd guess this story is very old, 1960's or earlier. The plot is nearly identical to the TZ episode I referenced. A humanoid space alien comes into a remote Mexican village. He's been wounded, and later dies. He brings a gift which is a book containing a vaccine or cure for cancer. The short story diverges from the tv episodes in several respects, though.
- The alien has been shot in the leg in the story, whereas he'd been wounded in the chest in the TZ episode.
- The alien is not shot dead by fearful villagers, as he is in the TZ ep. He dies from an allergic reaction to his bandages. Medical supplies being scarce, it's common practice in the village to use wrapping paper to bandage wounds. The alien is deathly allergic to some chemical in the paper (phenyl-something, IIRC), and dies from the reaction.
- Finally, the book isn't destroyed by fearful villagers, but by a somewhat hard-headed local priest, who casts the book into the flames believing the book to be the Devil's work. I think the cure in the book was known by the protagonist before the book was destroyed, rather than finding charred scraps as in the TZ episode.
Does this sound familiar to anyone? I checked on the TZ ep itself, and could not find any mention of an "inspired by" reference. Nor have I been able to find any story called "The Gift" that matches the description of the story I read. I have to think there's at least some connection, however.