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

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.

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

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.

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.

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.

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.

* 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.

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.

3. Ciliates Intestinal: Balantidium coli

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

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

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.

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.

Morphology

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

2- Precyst: Trophozoite withdraws its pseudopodia and becomes rounded and devoid of food inclusions. 3- Cyst: 10-18 μm, uninucleated and divides twice by mitotic division to form 4 nucleated cyst (infective stage).

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

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

Flask shape amoebic ulcer

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.

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

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

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. .

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.

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

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

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.

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

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

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.

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.

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.

Radiological image showing lung abscess

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.

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

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