Conventional wisdom states it makes its host ‘bolder’ to increase likelihood of them ending up in a feline stomach. I suspect there is more to the story though..
Surely there are better strategies for the parasite than increased host ‘boldness’ e.g semi-paralysis, visual impairment etc. Why boldness?.. well, pure speculation, but..
A strategy that is 100% beneficial for parasite and 100% detrimental for host would 100% incentivise host adaptation to 100% immunity. Bad news for parasite..
How about... a parasite cannot just intelligently pick parasitic features from a menu. Probably the "features" are hacks that happen to work, ish. Then improved upon a bit over time.
A parasite might fair better in one genotype than another. So it kinda needs that genotype/lineage to survive, even if it needs the specific host to die..
OK, but my reply was mostly to your "Why boldness?". The immune system of a mouse, while certainly not impenetrable, can be difficult to attack, and boldness might just have been the
part that happened to be most easy to attack. While I don't necessarily accept your suggestion that your other "strategies" would be better, they may have been harder to implement.
Also I'd like to point out that I spent a lot of time in my youth studying a mouse called Mickey, and it was often seen with a magnifying glass, negating visual impairment.
A very reasonable hypothesis! But I'd like to advice caution before a proper Scientific analysis has been performed to see whether said boldness is the actual cause and so on.
A double blind experiment might shed some light on this: Both the cat and the mouse is given a blindfold. To make it simpler a man named Occam might lend the cat a razor as weapon
Now I think about it, I also studied this mouse called Jerry, and I do not remember many other dangers it was subject to, beyond a fat woman standing on a chair screaming.
But.. facilitating a live-fast-die-young behaviour pattern in the host is something of a compromise. Sure, more hosts die, but maybe these mice father more kids before they do…