This document summarizes three genera of amoeba - Entamoeba, Endolimax, and Iodamoeba. It describes the species within each genus, including their morphology, life cycles, pathogenic nature, modes of transmission, and other characteristics. Key points include that Entamoeba gingivalis and Endolimax nana are commensal organisms in humans, while Entamoeba polecki and Iodamoeba buetschlii can cause infection but are generally nonpathogenic. Transmission for the cyst-forming species requires ingestion of the cyst stage, which can survive outside the host.

1. Three genera of family
Entamoebidae

2. Contents
 Genus Entameoba
Entameoba gingivalis (specie)
Entamoeba polecki (specie)
 Genus Endolimax
Endolimax nana (specie)
 Genus Iodamoeba
Iodamoeba buetschlii (specie)

3. Entamoeba gingivalis (specie)
 Entamoeba gingivalis was the first ameba of humans to be described. It is present
in all animals populations, lives only in their mouth.
 Like E. coli (Escherichia Coli), it is a commensal( an association between two
organisms in which one benefits and the other derives neither benefit nor harm).
Morphology.
 Trophozoites are 10 μm to 20 μm in diameter and seen as transparent. They move
quickly by means of numerous blunt pseudopodia. Only trophozoites are seen, but
cysts are not found.
Microscopic view

4.  The spheroid nucleus is 2 μm to 4 μm in diameter and has a small, nearly
central endosome.
 Food vacuoles are numerous and contain cellular debris, bacteria, and
occasionally blood cells.
Pathogenic nature:
 Entamoeba gingivalis is a commensal that lives on the surface of teeth and
gums, in gingival pockets near the base of teeth, and sometimes in tonsils.
 Abundant in cases of gum or tonsil disease, but no evidence that they cause
these conditions.
 Protozoa multiply rapidly with an increased abundance of food.
 Entamoeba gingivalis also infects other primates, dogs, and cats.

5. Mode of transmission
 Because no cyst is formed, transmission must be direct from one person to
another by kissing, by droplet spray, or by sharing eating utensils.
 Up to 95% of persons with unhygienic mouths may be infected, and up to 50%
of persons with healthy mouths may harbor this ameba.

6. Entamoeba polecki (specie)
 It is a zoonotic parasite,so disease it cause can jumped from non-humans to
humans.
Morphology
 More similar to E.histolytica
 Difference is E. polecki cysts have just one nucleus, only 1% of cysts reach
binucleate stage, but uninucleate cysts of E. histolytica are not seen much.
Life cycle
 There are two stages in the life cycle of E. polecki. The first is as a
trophozoite, a vegetative stage that cannot survive in the environment.
 The second is a cyst, where transmission of parasite is possible and provides
protection to harsh external environments.

7. Pathogenic nature:
Entamoeba polecki is usually a parasite of pigs and monkeys, although on rare
occasions it occurs in humans.
It is generally nonpathogenic in humans, but symptomatic cases may be difficult
to treat.
Nonspecific symptoms from infection have been reported, including nausea,
vomiting, diarrhea, bloody stools, and fever.

8. Genus Endolimax
 Members of genus Endolimax live in both vertebrates and invertebrates.
These amebas are small, have vesicular nucleus. The endosome is
comparatively large and irregular.
 Encystment occurs in the Endolimax nana.
Endolimax nana (specie)
 Lives in the human large intestine, mainly near the cecum, and feeds on
bacteria. Like E. coli (Escherichia Coli), it is a commensal.
Morphology
 The trophozoite of this tiny ameba measures 6 μm to 15 μm in diameter.
 The nucleus is small and contains a large centrally or eccentrically located
endosome.
 Pseudopodia are short and blunt, and the amebas move very slowly, the
characteristics from which their name, “dwarf internal slug,” is derived.

9. Fig: Endolimax nana (a) cyst (b) trophozoite - large karyosome and thin layer of chromatin
granules on nuclear membrane

10.  Large glycogen vacuoles are often present, and food vacuoles contain
bacteria, plant cells, and debris.
Cyst and presyst:
 Encystment follows the same pattern as in E. coli (Escherichia Coli) and E.
histolytica. Precyst secretes a cyst wall, thus formed cyst includes glycogen
granules and, small curved chromatoidal bars.
 The mature cyst is 5 μm to 14 μm in diameter and contains four nuclei.

11. Mode of transmission
 As with other cyst-forming amebas that infect humans, mature cysts must be
swallowed for infection to occur.
 Metacysts excyst in the small intestine, and colonization begins in the upper
large intestine.
Pathogenic nature
 Incidence of infection parallels that of E. coli (Escherichia Coli), and reflects
the degree of sanitation.
 Cysts are at more risk of decomposition due to putrefaction(Decomposition of
proteins by bacteria and fungi and production of foul smell) and desiccation
than E. coli.
 This protozoan is not a pathogen, its presence indicates that opportunities
exist for infection by disease-causing organisms.

12. Genus Iodamoeba
 The genus Iodamoeba has only one species, and it infects humans, other
primates, and pigs. Its distribution is worldwide.
Iodamoeba buetschlii (specie)
 Iodamoeba buetschlii is the most common ameba of swine, which probably
are its original host.
 The prevalence of I. buetschlii in humans is typically 4% to 8%, considerably
lower than that of E. coli or E. nana
 Trophozoites are usually 9 μm to 14 μm long.
 They move slowly by means of short, blunt pseudopodia.
 The nucleus is relatively large and vesicular, containing a large endosome that
is surrounded by lightly staining granules about midway between it and the
nuclear membrane.
Morphology

13.  Food vacuoles usually contain bacteria and yeasts. A large glycogen vacuole
stains deeply with iodine—hence the generic name.
Fig: Iodameoba buetschlii A-Trophozoite B-cyst.( presence of glycogen mass in cyst)

14. Precast and cyst:
 The precyst is usually long and contains no undigested food. It secretes the cyst
wall that also is usually oblong, measuring 6 μm to 15 μm long.
 The mature cyst nearly always has only one nucleus.
Pathogenic nature :
 Iodamoeba buetschlii lives in the large intestine, mainly in the cecal areas,
where it feeds on intestinal flora.
 A few reports of I. buetschlii causing abscesses like those of E. histolytica
probably were actually misidentifications of Naegleria fowleri (a brain eating
ameoba).
Mode of transmission
 Infection spreads by contamination, since mature cysts must be swallowed to
induce infection. It is possible that humans become infected through pig feces
as well as human feces.