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Parasitology is classified into Three main groups Protozology (proto = primitive) Study of Protozoa ‫بروتوزوا‬

Helminthology (Helminth = Worm) Study of Helminthes

Entomology ‫الديدان‬

Study of Arthropods ‫الحشرات‬

Dr. Sameh M.Mohamadi


The Protozoa 

Protozoa are:   

simple, single celled organisms, may be microscopic or seen by naked 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)

The cytoplasm is 

and chromatin granules. ectoplasm (clear) and endoplasm (granular) containing food vacuoles and other organelles.

Most of them are free living. Dr. Sameh M.Mohamadi


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. Dr. Sameh M.Mohamadi


1)Rhizopoda: Move by pseudopodia and divide by binary fission during the trophozoite active stage e.g. Entameba histolytica.

Dr. Sameh M.Mohamadi


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

Dr. Sameh M.Mohamadi


3)Zoomastigophora: Move by flagella and divide by longitudinal fission e.g. Giardia, Trichomonas & Trypanosoma.

Dr. Sameh M.Mohamadi


4)Sporozoasida: No special locomotor apparatus and reproduce sexually and asexually e.g. Malaria, Toxoplasma.

Dr. Sameh M.Mohamadi


Intestinal protozoa of medical importance 1)Entameba histolytica 2) Balantidium coli 3) Giardia lamblia ingestion (food, water...) Excystation In small intestine (Giardia) In large intestine (Ent., B. coli)

pass in feces

Trophozoite

mature cyst Multiply

encyst Dr. Sameh M.Mohamadi


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. Dr. Sameh M.Mohamadi 


Dr. Sameh M.Mohamadi


Morphology: Exist either as an active, motile, feeding Trophozoite form or as cyst resistant form Trophozoite minuta form. 10-20 Âľm

Wet mount preparations. Trophozoite

iodine stained.

Trichrome stained film. Cyst

Dr. Sameh M.Mohamadi iodine stained.

Trichrome stained film. Trophozoite magna form (dysenteric). 12-25 Âľm

ingested erythrocytes in the endoplasm.


Life cycle Entameba histolytica Entameba histolytica

Dr. Sameh M.Mohamadi


Dr. Sameh M.Mohamadi


Clinical findings Asymptomatic 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

flask-shaped ulcers

Complications are extra intestinal amoebiasis causing liver abscess via the portal vein or less commonly lung abscess, brain abscess, rarely appendicitis.

Liver abscess Dr. Sameh M.Mohamadi


Laboratory Diagnosis ď Ž

ď Ž

Stool or tissue biopsy for detection of motile Trophozoites in acute case. Stool shows blood and mucus, or cysts in chronic dysentery. ELISA for extra intestinal amebiasis.

Amoebic Offensive Blood & mucus Acid Few Motile ameba

Bacillary Odor consistency pH Pus cells Dr. Sameh M.Mohamadi

Odorless Watery &Bloody Alkaline Many -


Entameba Entameba Endolimax Iodameba Dientamoeba nana histolytica coli buetschlii fragilis

Trophozoite

Motility

Rapid

Food vacuole RBCS

Slow Bacteria

No. of nuclei One

two

Cyst Formation No. of nuclei

Form cysts

1-4

no cyst

1-8

1-4

Dr. Sameh M.Mohamadi

1

-


Dr. Sameh M.Mohamadi


Treatment  For

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. Dr. Sameh M.Mohamadi


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. 

Dr. Sameh M.Mohamadi


Morphology: Is the largest Protozoal parasite in man. Trophozoite

Trophozoite: showing cilia and arrow directed to the cytostome.

(50-200x40-70 ď ­m) wet mount preparation showing cilia

Trichrome stain Cyst: showing cilia and arrow directed to the cytostome.

Wet mount showing ImmatureDr. cyst Trichrome stain Sameh M.Mohamadi


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 serious complication.

Laboratory diagnosis: • Stool or tissue biopsy immediately examined or preserved to enhance detection of the Trophozoites. Cysts are less frequently encountered Dr. Sameh M.Mohamadi


Treatment: •Tetracycline, with •Iodoquinol and •Metronidazole as alternatives. •Tetracyclines are contraindicated in pregnancy and in children less than 8 years old. Dr. Sameh M.Mohamadi


Giardia lamblia  

Disease: Giardiasis. Geographical distribution:  

Worldwide. The parasite is more common in children.

Dr. Sameh M.Mohamadi


Morphology

Trophozoite in wet mount

Trophozoite stained

: 9-20 x 7-12 Âľm, it has a convex dorsal with trichrome. There are two surface and a flat ventral surface with a nuclei, two exostyles, four pairs of disk-like depression (sucking disk) used flagella and two median (parabasal) attachment to the columnar cells of the bodies. Dr. Sameh M.Mohamadi intestine.


Cyst: Oval, 8-14 x 5-10 Âľm, with two to four nuclei and remainings of flagella longitudinally oriented.

Cysts stained with Trichrome.

Dr. Sameh M.Mohamadi


Life cycle

Giardia lamblia

Dr. Sameh M.Mohamadi


Longitudinal fission

Dr. Sameh M.Mohamadi


ď Ž

ď Ž

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

Dr. Sameh M.Mohamadi


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. Dr. Sameh M.Mohamadi


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).

Dr. Sameh M.Mohamadi


Summary Location In Intestine

Entameba histolytica.

Balantidium coli

Giardia lamblia

Large

Large

Small

Diagnosis

Trophozoites & cysts in stool MOT Contaminated food or water with Infective stage Infective stage Mature cyst Diseases Treatment

Amoebiasis

Balantidiasis

Metronidazole (flagyl)

Dr. Sameh M.Mohamadi

Giardiasis


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