fungi
Fungi are simple eukaryotic organisms that consist of one or more cells. They include mushrooms and yeasts. Human diseases caused by fungi include ringworm and athletes foot. Both are skin diseases that are not usually serious. A ringworm infection is pictured below Figure below . A more serious fungus disease is histoplasmosis. It is a lung infection. Though fungal infections can be annoying, they are rarely as serious or deadly as bacterial or viral infections.