So the first thing that jumped out at me when watching the last of us was in the opening credits.
Not Pedro Pascal 😁 but Physarum Polycephalum. The iconic looking yellow growing organism that's used as a reference for a lot of the imagery:
The story indicates the fungus Cordyceps because it already infects and controls insects. So it's a believable premise that it could infect humans.
However.
The opening credits clearly show Physarum Polycephalum, or slime mould, which is not a fungus, but a giant single celled life form more closely related to an Amoeba.
Also, it's size and speed of growth would be better adapted to the kind of human controlling organism featured in the story. If it mutated and desired to eat more than just bread.
Here's a great video that goes into more detail about this fascinating life form:
It's also worth mentioning here that there is already a parasite that infects humans and may even affect our behaviour, another single celled offender by the name of Toxoplasma gondii, which is passed to humans who come into contact with cat litter or eat undercooked meat. We know it makes rats more tetchy, there's even a theory that it explains why people with lots of cats are a bit weird.
So I guess we should be looking out for a dangerous human controlling parasite, but single-celled might be more likely than fungus.
The 'Adult' PP organism is formed when two small Amoeba-like cells join together, and instead of creating a third organism, become a bigger one and start growing.
I wonder what would happen if someone let a dose of Physarum Polycephalum loose on some cat litter and it learned to cooperate with an obligate intracellular parasitic protozoan like Toxoplasma gondii?