Do you not realize fungi/bacteria/parasites are the most populous organisms in the universe? Not just on earth, but the UNIVERSE? That bacteria/microorganisms exist on the moon, Mars, etc. and we have PROOF of it? Also knowing that scientists haven't got the capability or manpower to FULLY realize how all of these organisms affect the world around us, nor even identify them all, that just adds another layer to the realm of possibilities.
Do you not realize that if there's some strain (wether manufactured or organically grown to become immune to vaccines, said fungi/bacteria/parasites CAN and WILL infest and and affect their "hosts" (in this case, humans)?
Not saying that if it were to happen, it would happen exactly as in-game. But the Center for Disease Control has NEVER ruled out the possibility of this happening. And several times has confirmed that out of all sci-fi/fantasy movie themes, an "outbreak" / "zombies" is the most likely to happen, if any. Read between the lines.
No one's saying mfers is walking around on some Frankenstein shyt. Nor am I scared that the shyt's legit going to happen. BUT the theme of the game is 100x more likely than ANYTHING in Bioshock taking place. If you kept up with science (no disrespect, just facts), then you'd realize how plausible this is, and laud Naughty Dog for creating a game that heavily draws from real-world plausibility and fact.
They went as in depth as possible with it, JUST SO the story could become so engaging, which is partially why it's been nominated and awarded MANY times over more than Bioshock. Not to mention everything from the weapon switch delay/system, emotion, & story...being a lot more realistic. This ain't even an argument, again. Just facts.
So as I said....LOU >>>>>> the fantasies/stretches of Bioshock.