Toxoplasmosis has been most thoroughly studied in rats and mice. Both species have a deep-seated, innate fear of cats for obvious reasons. Spray a bit of cat urine into a corner, and the rodent will avoid this location, well, like the plague. In contrast, an infected animal loses its innate fear of cats. By some measures, it even appears to be mildly attracted to the smell of felines. This is an unfortunate turn of events for the rodent, because it is now more likely to be successfully hunted by a cat. On the other hand, this is a great deal for T. gondii. When the cat devours the sick critter and its contaminated brain, T. gondii moves into its final host, where it reproduces, completing its life cycle. Not quite what the romantics have in mind when they write about “the circle of life”!