Disclaimer: I own nothing. All Buffy the Vampire Slayer characters and Machine of Death genre belong to their proper owners.
Author's Note: The following was first done as a private review to MarcusRowland's Machine of Death story 'In The Cards.' That author suggested I put it on Twisting the Hellmouth for a wider audience, so here it is! (In case you don't know the original idea, the Machine of Death is a mysterious computer which can identify without fail exactly how anyone who uses it will have their life end. However, the information is usually presented in the most succinct manner possible and often doesn't result in what the receiver of this grim news thinks will happen.)
Buffy looked at the terse message on the card from the Machine: VAMPIRE.
"Well, duh," she shrugged. What else was going to kill the oldest living Slayer? Not that Buffy was going to hide away from her blood-drinking foes and stop going on patrols for the New Council. As a matter of fact, she was already late for the usual yearly apocalypse involving lots of those fanged fiends, this time somewhere in Central America.
It wasn't all that bad, though, despite the couple of nights their Slayer/Watcher forces had to spend camping outside an overgrown Mayan temple deep among the Guatamelan rain forest. Buffy and the others ambushed, Slayed, and partied quite nicely before the blonde flew home to Scotland.
Except on the airplane, Buffy went into a sudden seizure which soon ended in death. The shocked witnesses still saw for some reason a faint smile on the lips of the small woman who'd perished in their company.
A grieving Scooby Gang learned to their bewilderment that Buffy's normally super-efficient Slayer healing had fallen victim to a very rare form of rabies. No one ever found out how she'd acquired her fatal illness, since even Buffy never noticed the small nick on her bare arm the first morning after sleeping rough in the jungle. There, a stray winged mammal had landed late at night and fed upon Buffy's blood, passing on the deadly disease carried along by a common vampire bat (Desmodus rotundus).