It really does exist.
Only really touched on in the film but much more detail in the book.
Look it up. Truly fascinating how it works on the host and as CREEPY as hell.
each species targets a species of insects/plants. we eat cordyceps here in asia, as a potent herb. it looks like a dried worm. and definitely seems plausible, if it one day evolves to target humans.
shareRabies is also pretty sinister, and they made all sorts of movies and short stories about it back in the 70's when they first started to understand it's life cycle. Kinda like folks do today with Cordyceps.
The first thing the rabies infection does upon entering an animal is to move in to deep muscle tissue to avoid detection and to multiply, this can take a couple of weeks to 21 days and the virus can be stopped during this phase if the vaccine is successful in finding it.
The second thing the infection does once it has spent that time building up a foothold in it's victim is to break down the protective coating on a nearby nerve bunch so that it can use your body's nervous system as an elevator to the brain. This manifests as tingling or pins and needles at the scene of the bite, pretty much every single person who experiences this will now be told the news that they will die within a week as only 2 people have ever survived after that point. Both American victims of bat bites and both after spending weeks in a medically induced coma having experimental chemical combinations pumped through their body. Neither made complete recoveries.
The third stage is hydrophobia, the virus upon reaching the brain drops down in to the three main salivary glands of the mouth and begins to multiply rapidly, the infection has also switched off the bodies immune system by this point and increased production of saliva, it then damages a very specific part of the lower brain that triggers a gagging reflex at the sight or sense of water. All of this is to turn the animals mouth in to the perfect infecting tool and to stop it inadvertently swallowing infected saliva before it can be used.
The final stage is fear, the virus triggers another autonomic response that induces paranoia and confusion in order to make the animal aggressive to other animals in the hope that it will bite them and start the cycle anew. By this point brain damage is such that an infected person will likely die within 5 days of the infection reaching the nervous system but that is 5 days to attack anything that comes close.
One misconception is that rabies makes all animals bite, but in humans it makes us lash out with our arms, this is because Rabies doesn't program infected animals to bite, it just increases their aggression seeing as all mammals bite already if provoked enough. The virus clearly hasn't caught up with the fact that a provoked human is more likely to try and hit an opponent with a rock rather than bite them.
I've often wondered that if Cordyceps ever made the jump from insects and arachnids to mammals, what would happen if Rabies and Cordyceps occured in the same host. It's a good thing I'm not a multibillionaire boffin biologist because curiousity usually wins over caution.
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