Non-pathogenic intestinal protozoa are single-celled parasites commonly found in the intestinal tract but never associated with illness. Entamoeba coli, E. hartmanni, E. polecki, Endolimax nana, and Iodamoeba buetschlii are generally considered nonpathogenic and reside in the large intestine of the human host. The most dramatic incident in the USA was the Chicago World's Fair outbreak in 1933 caused by contaminated drinking water; defective plumbing permitted sewage to contaminate water. There were 1,000 cases (with 58 deaths). In 1998 there was an outbreak of amoebiasis in the Republic of Georgia. Between 26 May and 3 September 1998, 177 cases were reported, including 71 cases of intestinal amoebiasis and 106 probable cases of liver abscess.
Good sanitary practice, as well as responsible sewage disposal or treatment, are necessary for the prevention of E.histolytica infection on an endemic level. E.histolytica cysts are usually resistant to chlorination, therefore sedimentation and filtration of water supplies are necessary to reduce the incidence of infection. To help prevent infection:
•Avoid raw vegetables when in endemic areas, as they may have been fertilized using human feces.
•Boil water or treat with iodine tablets.
•Avoid eating street foods especially in public places where others are sharing sauces in one container