المحاضرة الثانية - طفيليات

Dr. Sameh M.Mohamadi

Parasitology is classified into Three main groups

Protozology(proto = primitive)

Study of ProtozoaHelminthology

(Helminth = Worm)Study of Helminthes

Entomology

Study

of Arthropods

بروتوزوا

الديدان

الحشرات


The Protozoa

Protozoa are:

simple,

single celled organisms, may be microscopic or seen bynaked eye

consisting of nucleus and cytoplasm.

The nucleus contains

a karyosome (An irregular aggregation of chromatin in the nucleus of a cell not

undergoing mitosis)

and chromatin granules.

The cytoplasm is

ectoplasm (clear) and

endoplasm (granular) containing food vacuoles and other organelles.

Most of them are free living.


Classification According To Mode of Movement

1)Rhizopoda: Move by pseudopodia and divide by

binary fission during the trophozoite active stage e.g. Entameba histolytica.

2)Ciliata: Move by cilia and divide by transverse

division e.g. Balantidium coli.

3)Zoomastigophora: Move by flagella and divide

by longitudinal fission e.g. Giardia, Trichomonas & Trypanosoma.

4)Sporozoasida: No special locomotor apparatus

and reproduce sexually and asexually e.g. Malaria, Toxoplasma.


1)Rhizopoda: Move by pseudopodia and divide by binary

fission during the trophozoite active stage e.g. Entameba

histolytica.


2)Ciliata: Move by cilia and divide by transverse division e.g.

Balantidium coli.


3)Zoomastigophora: Move by flagella and divide by

longitudinal fission e.g. Giardia, Trichomonas &

Trypanosoma.


4)Sporozoasida: No special locomotor apparatus and

reproduce sexually and asexually e.g. Malaria, Toxoplasma.


Intestinal protozoa of medical importance1)Entameba histolytica

2) Balantidium coli 3) Giardia lamblia

ingestion

(food, water...)

In small intestine (Giardia)

In large intestine (Ent., B. coli)

Excystation

Trophozoite

pass in feces

mature cyst

encystMultiply


Entameba histolytica

Disease:

Amoebic dysentery or

amoebiasis.

Worldwide

tropical & subtropical countries.

10% of the world are carries.

Habitat: The

un-encysted parasites occur in the large intestine of

man and monkey

liver where they give rise to amoebic abscess.


Morphology: Exist either as an active, motile, feeding

Trophozoite form or as cyst resistant form

Trophozoite minuta form.

10-20 µm

Trophozoite magna form

(dysenteric). 12-25 µm

ingested erythrocytes in

the endoplasm.

iodine stained. iodine stained.

Wet mount preparations. Trichrome stained film. Trichrome stained film.

Trophozoite Cyst


Life cycle

Entameba histolyticaEntameba histolytica


Clinical findingsAsymptomatic carriers harboring the non-invasive small form

trophozoite (minuta form)

magna form invades the wall of the intestine causing abdominal pain

and diarrhea

It may cause small ulcers that fuse together forming large flask-shaped

ulcers, through the muscular mucosa into the submucosa

Complications are extra intestinal amoebiasis causing liver abscess

via the portal vein or less commonly lung abscess, brain abscess,

rarely appendicitis.

flask

-sh

ap

ed

ulc

ers

Liver abscess


Laboratory Diagnosis

Stool or tissue biopsy for detection of motileTrophozoites in acute case. Stool shows blood

and mucus, or cysts in chronic dysentery.

ELISA for extra intestinal amebiasis.

BacillaryAmoebic

Odorless

Watery &Bloody

Alkaline

Many

-

Odor

consistency

pH

Pus cells

Offensive

Blood & mucus

Acid

Few

Motile ameba


Entameba histolytica

Entameba coli

Endolimax nana

Iodameba buetschlii

Dientamoeba fragilis

Trophozoite

Motility

Food vacuole

No. of nuclei

Rapid Slow

RBCS Bacteria

One two

Cyst

Formation

No. of nuclei

Form cysts no cyst

1-4 1-8 1-4 1 -


TreatmentFor acute dysentery:

Metronidazol (flagyl),

Tinidazole (fasigyn) or

Secnidazole (flagentyl) and

Tetracycline or Erythromycin to prevent

2ry bacterial infection.

For chronic dysentery:

Intetrix or entobex and

Chloroquine for hepatic abscess.


Balantidium coli Disease:

Balantidiasis or

balantidial dysentery.

Geographical distribution:Worldwide, especially in areas were pigs are

raised.

Habitat: The Trophozoite is found in the large intestine of man

and pig.

The cysts are formed in the intestine. Trophozoites

pass in man feces in acute cases and the cysts in

chronic cases.


Morphology: Is the largest Protozoal parasite in man.

(50-200x40-70 m) wet mount

preparation showing cilia

Wet mount showing Immature cyst

Trophozoite: showing cilia and

arrow directed to the cytostome.

Cyst: showing cilia and arrow

directed to the cytostome.

Trichrome stain

Trichrome stain

Trophozoite


Clinical findings: Asymptomatic infection is common.

If the Trophozoite invade the intestinal wall it

causes inflammation and ulceration leading to

persistent or recurrent diarrhea, occasionally

dysentery with blood and mucus in feces.

Extra-intestinal infection does not happen,

however, intestinal perforation is a rare seriouscomplication.

Laboratory diagnosis:• Stool or tissue biopsy immediately examined or

preserved to enhance detection of the Trophozoites.

Cysts are less frequently encountered


•Tetracycline, with

•Iodoquinol and

•Metronidazole as alternatives.

•Tetracyclines are contraindicated in

pregnancy and in children less than 8

years old.

Treatment:


Giardia lamblia Disease: Giardiasis.

Geographical distribution: Worldwide.

The parasite is more common in children.


: 9-20 x 7-12 µm, it has a convex dorsal

surface and a flat ventral surface with a

disk-like depression (sucking disk) used

attachment to the columnar cells of the

intestine.

with trichrome. There are two

nuclei, two exostyles, four pairs of

flagella and two median (parabasal)

bodies.

Morphology

Trophozoite stainedTrophozoite in wet mount


Cysts stained with Trichrome.Cyst: Oval, 8-14 x 5-10 µm, with

two to four nuclei and remainings

of flagella longitudinally oriented.


Life cycle Giardia lamblia


Longitudinal fission


Clinical findings The spectrum varies from asymptomatic to sever diarrhea

and malabsorption.

The parasites may attach to cells of intestine causing

abdominal pain, vomiting, chronic diarrhea and flatulence.

Trophozoites live attached to

the columnar cells of the villi

of the small intestine


Trophozoites appear like Several

sickle-like profiles are seen over

the epithelium

Malabsorption and debilitation may occur and

deficiency in fat-soluble vitamins due to interference with

fat absorption.


Laboratory diagnosis:

Stool analysis for mainly cysts, less commonly for

trophozoites.

The stool is offensive, bulky and pale colored.

Treatment:

Metronidazole (flagyl) or

Tinidazole (fasigyn).


Giardia lamblia

Balantidium coli

Entameba histolytica.

Summary

SmallLargeLargeLocation

In Intestine

Trophozoites & cysts in stoolDiagnosis

Contaminated food or water with Infective stageMOT

Mature cystInfective stage

GiardiasisBalantidiasisAmoebiasisDiseases

Metronidazole (flagyl)Treatment

المحاضرة الثانية - طفيليات

Documents

trophozoite form

trophozoite active stage

trophozoite cystdr

large intestine ofman

trichrome stained film

small ulcers

longitudinal fission

amoebic abscess