According to a Yahoo! News story, half of the world’s human population is infected with Toxoplasma, a parasite shown to alter the brain function of rats, inducing them into behavior that benefits the parasite but is suicidal for the rat. So what affect does it have on humans? I was amazed when I read the article.

Slashdot has a nice discussion on the article. Lots of interesting links from the discussion too. Also, Cecil Adams talks about it.

Still not sure that parasites can manipulate the behavior of host organisms? Consider these other cases:

• The lancet fluke Dicrocoelium dendriticum forces its ant host to attach to the tips of grass blades, the easier to be eaten. The fluke needs to get into the gut of a grazing animal to complete its life cycle.




• The fluke Euhaplorchis californiensis causes fish to shimmy and jump so wading birds will grab them and eat them, for the same reason.




• Hairworms, which live inside grasshoppers, sabotage the grasshopper’s central nervous system, forcing them to jump into pools of water, drowning themselves. Hairworms then swim away from their hapless hosts to continue their life cycle.