Protozoa on the Brain

Toxoplasma gondii is a protozoa. 

I used to think a protozoa was just a professional tozoa. But, no. It's a kind of one-celled animal. 

In this particluar case, it's a brain-invading parasite.

Your brain is probably fine. Only 20% of Americans are infected. And a lot of people don't seem to suffer any ill effects from the infection. But consider what it does to rodents:

T. gondii infections have the ability to change the behavior of rats and mice, making them drawn to rather than fearful of the scent of cats. This effect is advantageous to the parasite, which will be able to sexually reproduce if its host is eaten by a cat.

How clever of the parasite
to feed the rat to the cat
by making its brain
go slightly insane.

But I maintain it's impolite
to treat a host like that!