In this case the 'mind' is that of a grasshopper: Parasitic Hairworm Charms Grasshopper Into Taking It for a Swim - New York Times. The hairworm compels its host grasshopper into jumping in the water. Hopper drowns, long creepy worm exits.
I've blogged on a number of these stories -- biologists seem to find examples of parasite mind control or physiologic overrides everywhere they look. Makes me wonder again if we were different back when we had worms.
Which reminds me of Toxoplasmosis. I've been skeptical, but my skepticism is waning.
Which makes me think of HIV. Toxoplamosis is very common in HIV infected persons. Almost ubiquitious. If it does alter behavior, perhaps by making humans more careless and less inhibited, then toxoplama infection in HIV might have the side-effect of spreading HIV (and thus feathering its own bed). Creepy.
Update 9/27/05: On further consideration -- what about Syphilis? That treponeme has enough DNA and species adaptation that it would be a natural host controller. It would be logical for syphilis infection to increase promiscuous behavior ...