Single-celled parasites include malaria, the deadliest infection on Earth, which kills two to three million people each year. Like many viruses, the parasite is transmitted by mosquito bites. Other single-celled parasites include Giardia and amebic dysentery, both found in foul drinking water, and both causing severe diarrhea. Multi-cellular parasites include trichinosis, hookworm, roundworm and tapeworm. Often found in soil, wood or decaying vegetation, fungi are actually closer in evolutionary terms to us than to bacteria.
Fungi are decay organisms that can digest good stuff like plant matter and garbage.
Histoplasmosis, a fungal infection of the lungs and gastrointestinal tract, is a particular problem among AIDS patients and others with compromised immune systems.