Entamoeba gingivalis is a non-pathogenic protozoa (reported by some to cause disease) and is known to be the first amoeba in humans to be described.
It is found in the mouth between the gingival pockets and near the base of the teeth. Entamoeba gingivalis is found in 95% of people with gum disease and in 50% of people with healthy gums. The cyst formation is not present, therefore transmission is direct from one person to another by kissing, or by sharing eating utensils. Only the trophozoites are formed and the size is usually 10 micrometer to 20 micrometer in diameter. Entamoeba gingivalis have pseudopodia that allow them to move quickly. Their spheroid nucleus is 2 micrometer to 4 micrometer in diameter and contains a small central endosome. There are numerous food vacuoles and contain cellular debris, blood cells and bacteria.