2. Prof. Dr: Azza El-ghareeb Head of parasitology department
Medical protozology
Prepared by
Prof. Dr: Azza El-ghareeb
Head of parasitology department
October faculty of Medicine

3. Protozoa Protozoa are unicellular organisms (single cell)
Trophozoite cyst
Each protozoon performs all functions of life.
The protozoon is made of a mass of protoplasm differentiated into cytoplasm and nucleoplasm.
The cytoplasm consists of outer thin hyaline ectoplasm and inner voluminous granular endoplasm.

4. Parasitic forms 1- Trophozoite
The cytoplasm is concerned with metabolism. It encloses:
a) Food vacuoles: containing food during digestion.
b) Volutin granules: stored food in the form of carbohydrate (glycogen vacuoles) or protein (chromatoid bodies)
c) Excretory vacuoles: collect waste products and discharge them to the exterior
d) The nucleus

5. 2- cyst
The nucleus is made of nuclear membrane, nuclear sap and chromatin.
In the vesicular nucleus, the chromatin is concentrated in a mass (the karyosome) or distributed between the karyosome and the inner surface of the nuclear membrane (peripheral chromatin).
In the massive nucleus the chromatine is distributed diffusely.

6. Biology Nutrition: by:
a) Absorption of liquid food through the body surface or.
b) Ingestion of solid particles by the help of pseudopodia or through the cytosome.
Excretion: either by:
a) diffusion through the body surface
b) excretory vacuoles.
Secretions:
a) Digestive enzymes
b) Toxins
c) Material for cyst wall
d) enzyme to liquefy tissues.

7. a) Aerobic or b) Anaerobic Reproduction:
Respiration:
a) Aerobic or b) Anaerobic
Reproduction:
a) asexual reproduction (simple fission)
b) sexual reproduction:
The formation of 2 cells (male and female gametes) by reduction division, and their union (or syngamy) resulting the formation of a zygote.

8. Locomotion: either by:
a) Pseudopodia (amoeboid movement).
b) Flagella: whip-like filaments arise from the kinetoplast (blepharoplast + parabasal body).
c) Cilia: like flagella but smaller and more numerous covering most of the body.
Cyst formation: Encystment of some protozoa is essential for survival outside the body of the hsot and during transmission from host to host.

9. * Protozoa are classified according to types of organs for locomotion into
1. Amoeba (Rhizopoda)
a) Intesitnal: e. histolytica & E. hartmani & E. coli and Iodamoeba butschlii and Endolima x nana & Dientamoeba fragilis.
b) Free living: Naegleria fowleri & Acanthamoeba.
c) Buccal: E. gingivalis
d) Coprozoic: Sappinea diploidea.

10. 2. Flagellates a) Intestinal: Giardia lamblia & Trichomonas hominis
b) Buccal: Trichomonas tenax
c) Urogenital: Trichomonas vaginalis
d) Blood flagellates:
i- Intracellualr: Leishmania.
ii- Extracellualr: Trypanosomes.

11. 3. Ciliates
Intestinal: Balantidium coli

12. 4. Apicomplexa (Sporozoa) are obligate parasites; no free-living forms
Absence of cilia and flagella
Parasitic forms
Sporozoite stage
Merozoite stage
Cyst stage

13. CLASS: Rhizopoda (Amoeba)
Entamoeba histolytica
Entamoeba coli
lodamoeha butschlii
Endolimax nana
Dientamoeba, fragilis
Entamoeba gingivalis

14. Entamoeba histolytica
Histo: tissue
Lytica: dissolve
Geog. Distribution: Cosmopolitan. In Egypt the disease is prevalent in all parts of the country.
Disease: amoebiasis or amoebic dysentery.

15. There are two species of Entamoeba:-
Entamoeba dispar
non invasive non pathogenic strain of E.histolytica as based on antigenic differences genomic DNA and isoenzyme electrophoresis.
Entamoeba hartmanni
Resembles E.histolytica except in size. The trophozoites is less than 10μm, do not ingest red blood cells, and their motility is generally less vigorous than that of E.histolytica.

16. Morphology

17. 1- Trophozoite: Average size 20 u Ecto- and endoplasm differentiated
Inclusions:
I- R.B.Cs.
present
2- Bacteria
Absent
3-. Vacuoles
Motility
Active
Nucleus: 1
1- karyosome
Small central
2- Peripheral chromatin
fine granules of equal size and even distribution

18. 2- Precyst: Trophozoite withdraws its pseudopodia and becomes rounded and devoid of food inclusions.
3- Cyst: μm, uninucleated and divides twice by mitotic division to form 4 nucleated cyst (infective stage).

19. Life cycle
Habitat: large intestine of man mainly caecum & sigmoido-rectal region.
Infective stage:
Quadrinucleate cyst
25µ
Trophozoite
Mode of Infection:
caecum
Ingestion of quadrinucleated cyst through autoinfection, contaminated food or drink and by Musca

21. 1-Intestinal amoebiasis
Pathogenesis
1-Intestinal amoebiasis .
trophozoites invade intestinal mucosa. .
Trophozoites produce histolytic enzymes .
that produce necrosis of mucosa
Histolytic enzymes
leading to the formation of flask-shaped ulcer. as primary lesion
Trophozoites exist in the base of the ulcer

22. Flask shape amoebic ulcer

23. Amoebic granuloma (amoeboma) develops on the wall of large intestine as a sequel to amoebic ulcer. It is relatively firm, nodular with fibrous outer wall under edematous mucosa.
It occurs mainly in the caecum and rectosigmoid. Clinical findings (pain, palpable mass, obstructive symptoms and hemorrhage). X-ray findings may simulate a bowel neoplasm.

24. post-dysenteric ulcerative colitis
Complications
Perforation of ulcer.
General peritonitis
Haemorrhage.
Stricture of colon.
post-dysenteric ulcerative colitis
Appendicitis

25. Extraintestinal amoebiasis
Extra-intestinal invasion to brain, liver, lung or skin. By haematogenous spread or by direct spread from the primary large intestinal lesions
Brain abscess
Lung abscess
Skin abscess
Liver abscess
Trophozoites may erode blood vessel
Trophozoites pass in blood

26. The parasites live as commensals in the intestinal lumen.
Clinical Picture
Asymptomatic: (cyst passers about 75%):
The parasites live as commensals in the intestinal lumen.
Non dysenteric amoebiasis (chronic amoebiasis):Symptoms range from mild to intense and long lasting. There is diarrhea alternating with constipation, abdominal cramps, flatulence, nausea, anorexia but no visible blood in the stool. If not treated, may pass to frank dysentery. .

27. c) Dysenteric amoebiasis (Acute amoebiasis):
This is found in 5% of infected cases.
It starts with abdominal discomfort and tenesmus. The number of stools increases (up to 10 to 20/day), little fecal material is present, but blood, mucus, and necrotic tissue, there is fever, colic, vomiting and abdominal tenderness.

28. Differentiation between amoebic dysentery and bacillary dysentery
Typical amoebic dysentery stool
Typical bacillary dysentery stool
Stool is Bulky
Stool is Scanty
Acidic
Alkaline
Scanty exudate
Massive exudate
Pus cells +
Pus cells +++
Blood +
Blood +
Charcot Leyden crystals:
Charcot Leyden crystals:
(Disintegrated eosinophils)
Absent
Present
Entamoeba trophozoites: present
Entamoeba trophozoites: absent

29. Haematogenous spread of Entamoeba trophozoites
Brain abscess
Trophozoite
Lung abscess
Histolytic enzymes
Skin abscess
Liver abscess
Blood vessel

30. Extraintestinal: Amoebic hepatic, pulmonary, cerebral and renal abscesses that are difficult to be suspected clinically but diagnosed serologically and radiography (using X-ray, CT and/or MRI). Usually associated by fever and leucocytosis.

31. Hepatic amoebiasis Pulmonary amoebiasis Amoebic Hepatitis
Trophozoites reached the liver through blood stream cause:
Trophozoites reached the lung through blood stream cause:
Amoebic Hepatitis
Fever
Leucocytosis
Pain in the right hypochondrium
Evidence of consolidation
Enlarged tender liver
Abscess may erode a bronchus
Amoebic Abscess
Fever
Trophozoites appear in sputum
Leucocytosis
Enlarged tender liver

32. Diagnosis of Intestinal Amoebiasis
I- Clinically
Dysentery
Painful frequent evacuation of small quantities of stool containing mucus tinged with blood.
II- Laboratory
1- Direct examination of stool
2- Indirect diagnosis
III- Radiological examination
IV- Sigmoidoscopy

33. 1.Intestinal amoebiasis
a) Stool examination:
In acute amoebiasis examination of a fresh dysenteric fecal specimen or rectal scraping for trophozoite stage. (Motile amoebae containing red cells are diagnostic of amoebic dysentery).
In chronic amoebiasis examination of formed or semiformed feces for cyst stage.
(Cysts indicate infection with either a pathogenic E.histolytica or non-pathogenic E.dispar.)
b) Culture on specific media may be used.

34. Sigmoidoscopy
to visualize the ulcer, scrap, aspirate or take biopsy to see the trophozoites.
In mild cases there are usually no findings. However, characteristic amoebic lesions may be found in severe cases.

35. 2.Extraintestinal amoebiasis
I- Clinical: according to the organ affected
II-Laboratory:
a) Serology: More than 90% of patients have positive serologic titers. .
b): Aspiration of the lesion in selected cases may be of help in Detection of the parasite
c) Blood picture: leucocytosis.
d) PCR.
Amoebic liver abscess
III- Radiology: Liver scanning
& pulmonary lesions.

36. Radiological image showing lung abscess

37. Treatment
a) Acute, fulminating amebiasis is treated with Metrondiazole; 750 mg three times daily for 10 days followed by iodoquinol,
b) Asymptomatic carriage can be eradicated with Iodoquinol, Diloxanide Furoate, or Paromomycin.
c) Extra intestinal amoebiasis. can be treated with Metronidazole, Chloroquine, and Diloxanide Furoate.

38. Treatment of Amoebic abscesses by aspiration or open surgical drainage
Surgical drainage of abscess
Thick chocolate-coloured or anchovy-sauce pus with trophozoites
Aspiration of abscess

39. Prevention and Control
1. Improvement of sanitary conditions (safe water supply and proper sewage disposal).
2. Human excreta should not be used as fertilizers.
3. Examination and treatment of food handlers.
4. Treatment of cases and asymptomatic cyst passers.
5. Control of flies and other insects as cockroaches.
6. Personal prophylaxis