Power to mandydax @3 - but there may be more to the story of Toxoplasmosis.

A massive percentage of humans carry the infection, and although it's generally considered asymptomatic and harmless in people, there were reports some time ago that infected humans are more likely to take risks. I think the data came from the unusually high number of toxo carriers winding up in hospital with trauma from car crashes etc.

Don't know if the supporting data has gone further, but it sounds plausible to me: our neurophysiology can't be all that different from cats' (despite what cats might think), and if the proteins can get through the b/b/ barrier it sounds reasonable that they could affect us, too.

CD

Edit: OK, just LOOK at this stuff. And shit yourself:

http://www.natur.cuni.cz/~flegr/publpar.php