We've seen it throughout media before, a crazy mutation that creates zombies, rabid people, giant spiders, etc. I'm spot checking how crazy I can get with this short story I'm writing about a bacteria / fungus from space and what it can do to various species.
The main concept I'm going at is this novel disease spreads quickly, it tends to kill humans (likely close primate relatives as well), and mutates almost every other species it encounters. From algae in a lake growing exponentially, birds changing to have growths on their wings that drop and spread the infection that way, to fireflies that glow a different color releasing an infectious powder, to fish and trees that garner some kind of bioluminescence. Overall, it causes a massive change in the ecosystem as it spreads.
I know I'm doing a lot of hand-waving here, but I've got a few questions about generalities.
How fast can something like this could spread? How fast could these mutations occur? How much creative liberty am I taking?