Chaos carolinensis (Amoeba)

Many species that belong to the order Amoebida are free living, but some are well-known parasites of plants and animals. At least six forms of amoeba are parasitic in humans The most well known of these is Entamoeba histolytica, which causes amebic dysentery. This often occurs in epidemics when raw sewage contaminates water supplies or when soil for crops is fertilized with untreated human wastes.