2. Entamoeba
histolytica
is a parasite and lives in the
mucous and sub-mucous
layers of the large intestine
of man. It may occur in the
liver and lungs. Rarely it
invades brain, spleen etc.
causing ulcers. The disease
caused by the parasite is
known as “Amoebic
3. • The morphological characteristics are as follows-
Shape - not fixed(constantly changing position)
Size – 18-40 micrometer
Cytoplasm – Divisible into two portions-
a clear translucent ectoplasm and
agranular endoplasm. RBC are found
in the Endoplasm.
Nucleus- spherical, 4-6 micrometer
4. • Entamoeba histolytica
multiplies by binary
fission in the trophic
stage. They have the
capacity to encyst. Prior
to encystment the
parasite rounds up and
eliminates food vacuoles.
A cyst wall develops and
the nucleus divides first
into 2 and then into 4.
5. • Entamoeba histolytica is a
widespread and clinically important
protozoan parasite. It normally exists
in the human intestine without causing
clinical symptoms but can invade the
intestinal mucosa, which causes
serious intestinal (amoebic colitis) and
extraintestinal (amoebic liver abscess
[ALA]) diseases.
6. • A single stool
examination has a low
sensitivity of detecting
the parasite. The best
diagnostic method is
detection of E.
histolytica antigen or
DNA in stool. Clinical
diagnosis of
amebiasis is difficult
because of the
nonspecific nature of
symptoms.
7. • Mentronidazol is the
drug of choice in
treatment of patients
with symptomatic
intestinal and
extraintestinal
amoebiasis. Adult dose
of metronidazol is 400-
800 mg thrice daily for
5-7 days. The drug
should be administered
parenterally in patient
