Rowan is pretty much right. I'm not sure, and I couldn't find any information as to how that fungus operates, maybe cause no one checked to see how it actually works.
But the possibility of something creating a neurotoxin that affects you in such a manner, definitely possible. It might take a really long time for something to evolve to such a point where it makes you do certain things to favor the reproduction of whatever makes the toxin, but Id say possible.
It already happens, certain bacteria that produce what is essentially botox, which is indeed a neurotoxin which acts in the gap between neurons to stop the enzyme that breaks down acetylcholine, which is usually the neurotransmitter at neuromusculur junctions. basically it puts the muscles in a state of constant contraction, which is why it gets rid of wrinkles. point being, there are already microorganisms that secrete neurotoxins, just none such that they make people do things to favor the reproduction of said microorganisms, at least as far as I'm aware.
