Introduction of Protozoa and Entameoba PDF

 Dr. Nancy * harba Dr. Nancy Harba prof. Prof. medical parasitology parasitology Protozoa are microscopic unicellular organisms capable of performing all physiologic functions of life. Protozoa are microscopic unicellular organism that have a relatively complex internal structure and car...

 Dr. Nancy * harba Dr. Nancy Harba prof. Prof. medical parasitology parasitology Protozoa are microscopic unicellular organisms capable of performing all physiologic functions of life. Protozoa are microscopic unicellular organism that have a relatively complex internal structure and carry out complex metabolic activities Their body consists of protoplasm which is enclosed by a cell membrane and divided into outer ectoplasm and inner endoplasm. Inside the protoplasm, there are a nucleus, an endoplasmic reticulum, food storage granules, and contractile and digestive vacuoles. The nucleus contains clumped or dispersed chromatin.  - Locomotion by Pseudopodia Cilia Flagella Undulant movement (gliding) amoebae. ciliates flagellates sporozoa.  Life Cycle Stages of Protozoa Trophozoites Cysts Stages with a protective They are membrane or actively fed thickened wall. and multiply Protozoan cysts that must survive outside the host usually have resistant walls  Classification of protozoa according to their habitat: - Small Intestine: Giardia lamblia. - Large intestine: Entamoeba histolytica. - Blood: Plasmodium species. - Tissue: Toxoplasma gondii. - Urogenital: Trichomonas vaginalis. 1- Nutrition Liquid food Solid particles Absorption through the body surface. Diffusion through body Cytostome Phagocytosis using Pinocytosis as phagocytosis, but surface. pseudopodia the material is liquid form. Flagellates or sporozoa Ciliates Sporozoa Amoeba  2- Excretion osmotic pressure Contractile vacuoles which Cytopyge Deposition of the waste rupture to the outside products in the cytoplasm Flagellate Amoebae Ciliates As pigment in sporozoa  3- Respiration Aerobic Anaerobic Protozoa living in tissues & Protozoa living in the intestine blood. lumen.  4- Secretion Protozoa secrete: Digestive ferments and pigments Lytic enzymes help lysis and invasion of tissue. Toxins Cyst wall to resist unfavorable surrounding conditions and to transfer to other hosts without destruction  5- Reproduction Asexual reproduction Sexual reproduction Simple fission Multiple fission Conjugation Gametogony The nucleus and The nucleus divides into Exchange of Formation of male cytoplasm divide several parts at first, then nuclear material and female gametes into equal parts the cytoplasm divides between two followed by their forming two cells. forming several small organisms union to produce daughter cells. zygote. e.g. amoebae and flagellates as in ciliates (longitudinal)& ciliates (transverse). e.g. shizogony in sporozoa as in sporozoa  Geographical distribution: Worldwide especially in areas with poor sanitary conditions.  Habitat: Large intestine (caecum, colonic flexures and sigmoidorectal region).  D.H: Man  R.H: Dogs, pigs, rats and monkeys  Morphological Trophozoite characters stage - Size: 20μm (15 - 60μm). - Shape: Irregular. - Cytoplasm: Differentiated into ectoplasm and endoplasm. - Ectoplasm (Outer): Clear with a single finger like pseudopodia. - Endoplasm (Inner): Granular with: a. Nucleus:- - Shape: Spherical. - Karyosome: Small and central. - Peripheral chromatin: Fine granules of uniform size and regularly arranged on the inner surface of the nuclear membrane. b. Food vacuoles: May contain RBCs (no bacteria).  Mature cyst (Quadrinucleate ) - Size: 15 μm (10 - 20 μm). - Shape: Rounded with thick cyst wall. Contents: -  may contain one nucleus (mono-nucleated cyst), two nuclei (di-nucleated cyst) or four nuclei (quadri-nucleated cyst).  Glycogen vacuoles and chromatoid bodies (stored food). in the form of rods of cigar shaped structures  All cysts are diagnostic stages while only the mature quadri-nucleated cyst is the infective stage.  Mode of transmission 1) Contaminated foods or drinks or hands with human excreta containing mature cyst. 2) Handling food by infected food handlers as cookers and waiters. 3) Flies and cockroaches that carry the cysts to exposed food. 4) Autoinfection (faeco-oral or hand to mouth infection).  Pathogenesis and symptomatology  Trophozoites secrete cysteine proteinases to penetrate the extracellular matrix (collagen, elastin, fibrinogen, and laminin) causing invasive disease with host cell lysis and necrosis forming the classic flask-shaped ulcers with erosion of blood vessels and bleeding in acute infections.  Amoebae spread from the intestine to liver occurs through portal circulation.  Ulcers may be complicated by secondary bacterial infection with necrosis, sloughing, perforation, peritonitis  Clinical pictures I. Asymptomatic infections E. histolytica patients may be asymptomatic cyst passers II-Symptomatic infections a) Intestinal amebiasis (Dysenteric or Non-dysenteric colitis  The incubation period may vary from 1 week to 4 weeks.  The clinical picture depends on the parasite virulence factors and the host immune response.  Dysentery and diarrhea account for 90% of cases of invasive intestinal amebiasis.  There is gradual onset of colicky abdominal pain, frequent bowel motions (up to 10 per day), and tenesmus and dysentery (blood and mucus).  In severe cases, symptoms may begin suddenly with profuse diarrhea (over 10 stools/day), fever, dehydration, and electrolyte imbalances.  Ameboma is a chronic granulomatous lesion that develops in the cecum or rectosigmoid junction.  B)Extra-intestinal amoebiasis Due to invasion of the blood vessels by the trophozoites in the intestinal ulcer reach the blood to spread to different organs as:- 1-Liver: Amoebic liver abscess or diffuse amoebic hepatitis. 2-Lung: Lung abscess 3- Brain: Brain abscess and encephalitis.. 4-Amebiasis of the skin (Amebiasis cutis) on the abdominal wall due to rupture of an intestinal or hepatic lesion.  Diagnosis 1) Clinical. 2) Laboratory a. Direct:- Microscopic:- 1. Stool examination: Reveals either trophozoites (in loose stool) or cysts (in formed stool) by:- - Direct smear of fresh stool samples to observe the movements of trophozoite. - Concentration methods to increase the chance of parasite detection. -For morphological identification, permanent stained smear with trichrome or iron hematoxylin may be done. -Charcot-Leyden crystals (microscopic crystals formed of eosinophilic protein) may be found in association with E. histolytica in the stool of chronic patients. 2. Sigmoidoscopy: To see the ulcer or the trophozoites in aspirate or biopsy of the ulcer.  B-Indirect (serodiagnosis & Antigen detection Serological tests to detect anti-amoebic antibody, include immunofluorescent antibody tests (IFAT), indirect haemagglutination assays (IHAs), radioimmunoassay (RIA), and enzyme- linked immunosorbent assays (ELISAs). ELISAs are the most sensitive and specific in patients with amoebic liver abscesses. The results of serological tests may be negative in acute disease and should be repeated in 5-7 days. Stool Antigen detection. Molecular diagnosis. Radiological investigations e.g., ultrasonography and CT for diagnosis of complications as liver abscess and ameboma.  Treatment Treatment 1-Medical treatment Metronidazol (Flagyl) or Tinidazole (Fasigyn) Diloxanide furoate or Paromomycin  Luminal amoebicides (diloxanide furoate and iodoquinol): 2-Surgical treatment Surgery for patients with rupture of the abscess, intestinal perforation and appendicitis.  Prevention and control 1) Treatment of patients and carriersProper washing of vegetables. Sanitary se Pure water supply Avoid using of human excreta as fertilizer. Fly control. Personal hygienic measures (washing Geographical Distribution: worldwide. Because pigs are the primary reservoir (63% to 91% of pigs harbor B. coli), human infections occur more frequently in areas where pigs are raised, and sanitation is inadequate. Habitat: large intestine (caecum, colon). Definitive Host: Man. Reservoir host: Pigs, less common monkey Infective stage: Mature cyst. Diagnostic stage: cyst and trophozoite  Morphology Trophozoite:  Size: 60 × 45 µm (largest protozoon of man).  Shape: ovoid, tapers at the anterior end with boring motility. It is covered with a layer of cilia (organ of locomotion).  It has a small cytostome (primitive mouth) which leads to cytopharynx that extends to 1/3 of the body length.  Nuclei: It has two nuclei, Kidney-shaped macronucleus (appear as a hyaline mass, especially in unstained preparations) and small spherical micronucleus (often not readily visible, even in stained preparations).  Cytoplasm: granular cytoplasm, contains two contractile vacuoles, food vacuoles, as well as ingested microbes (bacteria). Cyst: It is the resistant, and the infectious form. Size: 52 to 55 µm. Shape: Subspherical to oval, Double cyst wall with row of cilia visible in between cyst wall layers. Nuclei: two; the macronucleus and micronucleus, Cytoplasm: granular cytoplasm contains One or two contractile vacuoles.  Mode of transmission 1) Contaminated foods or drinks or hands with human excreta containing mature cyst. 2) Handling food by infected food handlers as cookers and waiters. 3) Flies and cockroaches that carry the cysts to exposed food. 4) Autoinfection (faeco-oral or hand to mouth infection). Life cycle: Multiplication of the trophozoite occurs by transverse binary fission, from which two young trophozoites emerge.  Clinical picture: Disease: Balantidiasis  Severe infection is characterized by abdominal pain and tenderness, tenesmus, nausea, anorexia, and watery stools with blood and pus. Ulceration of the intestinal mucosa and secondary bacterial invasion into the eroded intestinal mucosa can occur.  Chronic infections may develop in the form of a tender colon, anemia, cachexia, and occasional diarrhea, alternating with constipation.  Extraintestinal invasion of other organs is extremely rare in balantidiasis. Complications:  Haemorrhage.  Secondary bacterial infection.  Appendicitis.  Intestinal perforation and peritonitis  Diagnosis: History and Clinical picture Laboratory: Stool examination: for detection of cysts and trophozoites. Colonoscopy or sigmoidoscopy to obtain a biopsy specimen from the large intestine, which may be an evidence for the presence of trophozoites. Treatment:  Tetracycline: adults: 500 mg orally four times daily for 10 days.  Metronidazole: adults: 500-750 mg orally three times daily for 5 days. Children: 35-50 mg/kg/day orally in three doses for 5 days Prevention and control: As in amoebiasis Care in handling pigs in pig farms and slaughterhouses.