A predator or a disease would naturally evolve to keep the depressed population down.
As Gawande notes, it's really crucial to talk about end of life care, to not just push on, as if the disease is not evolving.
Nobody knows when or even if the disease will evolve the ability to pass easily from person to person.
The disease evolves and advances over decades, 30 being the mean years to death since onset.
I can't imagine that such a perverse disease could have evolved by accident.
The history of malaria predates humanity, as this ancient disease evolved before humans did.
It is rapidly replacing quinine derivatives and later drugs against which the disease has evolved into resistant strains.
Can you imagine how long they must have been eating each other if a disease evolved to take advantage of it?
The disease typically evolves over days to weeks with fever and headache.
But disease and parasites would evolve eventually, given enough prey.