That’ll be Ophiocordyceps unilateralis. It invades the ant’s brain and causes it to leave it’s nest and go somewhere better for the fungus then wait to die as the fungus errupts from its head.
If we’re talking about nightmare mind control horrors, we shouldn’t forget our old friend toxiplasmosis gondii, which infects rodents, then alters their behaviour so they’re not afraid of cats, in particular. This leads to the rodent getting eaten so the parasite can infect the cat, which is the only place it can reproduce, before spreading from the cat faeces back into the rodent population. It can also infect humans where there is evidence that it affects behavior too, particularly making males more careless of rules.
Sleep well.
Oh come now, there are so many more interesting parasites that mess with your brain for their own benefit; Trypanosoma which messes with your sleep before slowly killing you, Naegleria fowleri that just straight up eats your brain and a host of others that do weird and wonderful things.
Look at it this way; before you were surrounded by mind controlled ants, suicidal rodents and other such horrors without even knowing it. Now you do know about them. What’s that? I’m really not helping? Ok, I’ll stop.
And don’t forget the slow and almost certain agonising death of rabies for which we have no cure
This is a good place to leave this link to a nice folk song about parasites that has a verse on Toxoplasma of course
And those little things might make you kinky. https://journals.sagepub.com/doi/pdf/10.1177/1474704916659746 (One of my favorit papers because a friend of mine got them)
Wait they can effect humans now?!?! And they’re capable of understanding rules enough to get us to actively break them!?!?!?
I don’t think they understand ‘rules’, rather they mess with the brain structures that control self regulation. It’s believed that around 30-50% of the human population may have a T. gondii infection, with a corresponding link to other diseases. High levels may also go some way to explaining the prevalence of high risk behaviors in certain areas, although proving a correlation is challenging due to confounding factors.