Introduction
1. The only pathogenic amoeba among all of the intestinal amoebae
2. Infecting perhaps 10% of the world's population.
3. Lead to invasive amoebiasis.
4. Taxonomy:
| Kingdom | Subkingdom | Phylum | Class | Order | Family | Genus+Species |
| Protista | Protozoa | sarcomastigophora | Lobosea | Amoebida | Entamoebidae | Entamoeba Histolytica |
Morphology
Pay your attention to stages that have diagnostic value
Parasites stained with hematoxylin is described here.
1. cyst(non-motile)
(1) 10-20 mocrometers in size
(2) spherical in shape
(3) 1-2 nuclei (immature cyst); 4 nuclei (mature cyst-infective stage).
(4) inclusions:(become smaller and smaller as the cyst ages)
glycogen vacuole appears as a clear space; food reservoir
chromatoid body dark blue rods or dots; its function is not known
2. trophozoite(active form)
(1) Size: 10-40 micrometers in diameter, some are above 60 micrometers.
(2) Pseudopodium(ectopalsmic protrusion):
A broad or finger-like in form
B thrust out quickly
C firstly, formed with ectoplasm, secondly, endoplasm flows slowly into it.
D motility is progressive and directional.
(3) Endoplasm: red blood cells may be found in it.
(4) Nucleus(vesicular type)
It is not visible in an unstained specimen; but its clear structure can be seen when stained with hematoxylin.
A: membrane: distinct line
B: chromatin granules: fine ane uniformally arranged in the inner surface of the nulear membrane.
C: karyosome: small and centrally located.
Life Cycle
1 infective stage: mature cyst
2 access:mouth
3 ecological niches:large intestine; liver, lung and other organs.
4 pathogenic stage:trophozoite
5 diagnostic stage:cyst; trophozoites
Pathogenesis
一、Clinical classification
Asymptomatic infection (carrier)>90% cases
sympomatic cases<10%
A. Intestinal amoebiasis
a. dysentery
b. non-dysenteric colitis
c.appendicitis
d.amoeboma
B. Extra-intestinal amoebiasis
a. Hepatic
(1) acute non-suppurative
(2) liver abscess
b. Pulmonary
c. Brain
d. Skin
e. Other extra-intestinal amoebiasis
