MicrobiologyA protozoan, a microsporidia.
Drinking stool contaminated water. As most water is. That's why I drink only red wine. According to WC Fields, fish do something in water that may make it unpalatable. Or so they say.
Normal people can often get asymptomatic infection with chronic excretion (Ref).
And in Red Bellied Tree Squirrels (Callosciurus erythraeus) in Sichuan, China. So beware the Red Bellied Tree Squirrel feces.