Is it possible for a world-wide plague to start off as seemingly different diseases?

In the case of a world-wide plague epidemic that'll trigger the near extinction of humanity, is it possible that a virus/disease has inconsistent symptoms so that people aren't aware that it's really the same plague until it's already spread or in the later stages?

This is assuming that the plague either originated from one part of the world or perhaps started off in several places in individual forms before it mutated as one new strain once the right conditions were met.

Is this a possibility? Bonus points if you can explain how diseases/viruses begin in the first place or mutate and become resistant - whether the disease/virus is natural or manmade. :-)

Thanks in advance!

posted about 10 years ago

KaguraRap‭

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