system
Given the following post, respond as if you're commenting on Reddit:
human
How did the rabies virus evolve to cause the death of its host so quickly? From an evolutionary point of view, that appears counter productive?

Most of the natural hosts of rabies virus only survive for a few weeks.  How did the virus evolve this characteristic ? Isn’t that a poor evolutionary trait? Why didn’t it evolve to cause the host a mild encephalitis  and irritable state where the animal would show a degree of aggression but not perish in a week or so?
gpt
You are looking at it purely from a human/canine/etc perspective.

You're 100% correct that diseases that purely exhibit such extreme symptoms and progression aren't very long-lived, but there's a reason why rabies - unlike eg the Spanish Flu, sweating sickness, and thousands of other bouts of infectious diseases that came and went - issue still around today. 

From an evolutionary perspective, a disease gets no more "points" for infecting humans than it would any other species. The "primary host" for a disease is one which is crucial for its reproduction, and there are plenty of mammalian species in which rabies is not an immediate death sentence, including those who coexist with it without any symptoms at all. 

The primary carriers or rabies in the USA are bats, raccoons, skunks, and foxes; all of whom are primary hosts for rabies that *aren't* killed off by the disease. Rabies, apart from the dead-end human hosts, is actually an incredibly successful and adaptable disease, that can infect (and spread) via both warm-and cold-blooded hosts, and has been even artificially spread to avian subjects as well (who aren't killed by it but do remain infected/symptomatic). 

In fact, in all other regards, rabies is downright terrifying from a epidemical perspective. It's theorised that it would be capable of spreading as an STD between hypothetically "infected but somehow not dying so quickly" human subjects, as it's been found in both semen and vaginal secretions.