It’s time to revisit that grand old parasite, the brain-infecting Toxoplasma. The more we learn about it, the more marvelously creepy it gets.

The Toxoplasma life cycle normally takes the parasite from cats to the prey of cats and back again. In the guts of cats, the parasites have sex and produce egg-like offspring which are shed with cat droppings. They can survive in soil for weeks or months. Rats and other mammals ingest the eggs, which produce cysts mainly in the brain. When the cats eat infected prey, they get infected.

Not so wise is the response of infected rats: in the enclosure experiments they either became indifferent to the smell of cats, or spent some extra time checking out the