Cytoplastospora and giardia. No physical symptoms other than the depression and the resulting bacterial infection in my digestive tract.

The Cytoplastospora is microbial and only found with a microscope.

I actually had no idea parasites could cause depression and got a little angry when the psychologist suggested I be tested for them.

"im here because I'm suicidal you idiot!"

"OK, I'm ordering a parasite test."

Thank God, he had seen it before and knew what he was looking at.