General Characteristics of Amebae The most important feature that separates amebae from other groups of Protozoans us the presence of pseudopods in their trophozoite form. Amebae have two morphologic forms: The cyst and the trophozoite form. Trophozoites are delicate, fragile and motile. The life cycles of all the intestinal amebae are similar. Replication is by binary fission.
Entamoeba coli Entamoeba coli Common Name none Infective Stage Mature cyst (Commensal; non-pathogenic) Diagnostic Specimen Stool Mode of Transmission Ingestion of cyst via contaminated food/ water Disease Caused None (non-pathogenic)
Entamoeba histolytica Entamoeba histolytica Common Name none Infective Stage Mature Quadronucleated cyst Diagnostic Specimen Stool Mode of Transmission Ingestion of cyst via contaminated food/ water
Differentiation of E. coli and E. histolytica Characteristics E. histolytica cyst E. coli cyst Size range 8 to 22 um 8 to 35 um Shape spherical to round Spherical to round Number of nuclei one to four one to eight large, irregular shape, Karyosome small and central eccentric Peripheral coarse and unevenly Chromatin fine and evenly distributed distributed Cytoplasm Finely granular coarse Cytoplasmic chromatoid bars, rounded Thin, splintered chromatoid inclusions ends bars Diffuse glycogen mass Diffuse glycogen mass
Iodamoeba butschlii Iodamoeba butschlii Common Name none Infective Stage Mature cyst Diagnostic Specimen Stool Mode of Transmission Ingestion of cyst via contaminated food/ water
Acanthamoeba species Acanthamoeba species Common Name none Infective Stage Mature cyst Diagnostic Specimen CSF, brain tissue, and corneal scrapings Mode of Transmission Inhalation of infective cyst or penetration through mucosa Disease Caused Granulomatous Amebic Encephalitis (GAE)
Naegleria fowleri Naegleria fowleri Common Name none Infective Stage Mature cyst Diagnostic Specimen CSF Penetration of ameboid trophozoite to nasal mucosa in Mode of Transmission contaminated water or inhalation of cyst in dust particles Disease Caused Primary Amebic Meningocencephalitis (PAM)
Chilomastix mesnili Chilomastix mesnili Common Name none Infective Stage Cyst Diagnostic Specimen Stool Mode of Transmission Ingestion of cyst via contaminated food/ water Disease Caused Not pathogenic
A Closer Look (Chilomastix mesnili)C. mesnili cystC. mesnilitrophozoite
Giardia lamblia Giardia lamblia Common Name None Infective Stage Mature cyst Diagnostic Specimen Stool Ingestion of mature infective cyst via contaminated food/ Mode of Transmission water Disease Caused Traveler’s Diarrhea (Giardiasis)
Leishmania species Leishmania species Common Name None Infective Stage Promastigotes Diagnostic Specimen Giemsa stained blood smear from infected area Mode of Transmission Bite of infected sandfly
Leishmania species Differentiation Leishmania species Vector Disease Caused Geographic location Sandflies (Lutzomyia, Mucocutaneous South AmericanLeishmania braziliensis Psychodopygus) Leishmaniasis Countries Sandflies (Lutzomyia, Visceral Leishmaniasis (Kala-Leishmania donovani Complex Phlebotomus) azar) Central and South L. donovani chagasi America Africa, India, Thailand, L. donovani donovani Pakistan Europe, Africa, L. donovani infantum Northern China SandfliesLeishmania tropica Complex (Phlebotomus) Cutaneous Leishmaniasis/ Highlands of Ethiopia, L. aethiopica Old World Leishmaniasis/ Kenya USSR, Iran, Israel, L. major Oriental Sore/ Jordan etc.. Afghanistan, India, L. tropica Baghdad/ Deli Boil Kenya etc..
Trypanosoma cruzi Trypanosoma cruzi Common Name none Infective Stage Trypomastigotes Diagnostic Specimen Blood Bite from defecating reduviid bug, blood transfusion, sexual Mode of Transmission intercourse, transplacental transfer Disease Caused Chagas’ Disease
Blastocystis hominis Blastocystis hominis Common Name None Infective Stage Thick walled cyst Diagnostic Specimen Stool Mode of Transmission Ingestion of cyst Treatment Abdominal cramping, diarrher, vomiting, nausea, fever
General Characteristics of Plasmodia The typical life cycle of each of the Plasmodium organism involves over two dozen morphologic forms. However, only 6 of the most commonly encountered forms in human specimens will be discussed and are listed chronologically: Ring Forms (Early Trophozoites) Developing Trophozoites Immature Schizonts Mature Schizonts Microgametocytes Macrogametocytes
A Recaptiulation Plasmodium vivax Typical Characteristics at a Glance Relative age of infected RBC Young and Immature RBC Appearance of Infected RBC Enlarged, distorted Morphologic Form Typical characteristics (based on Giemsa Stain) Ring Form Delicate cytoplasmic ring measuring 1/3 RBC diameter single chromatin dot ring surrounds a vacuole Developing Trophozoite Irregular ameboid appearance Ring remnants common brown pigment Immature Schizont Multiple chromatin bodies brown pigment Mature Schizont 12 to 24 merozoites occupying majority of the RBCs merozoites surrounded by cytoplasmic material brown pigment may be present large pink to purple chromatin mass surrounded by colorless to Microgametocytes pale halo brown pigment common Macrogametocytes round to oval cytoplasm eccentric chromatin mass
A Recapitulation cont’d Plasmodium ovale Typical Characteristics at a Glance Relative age of Infected RBC young and immature RBCs Appearance of Infected RBC oval and enlarged, distorted with ragged cell membranes Morphologic Form Typical characteristics (based on Giemsa Stain) Ring Form Resembles that of P. vivax Ring larger in size than P. vivax Ring often thick and somewhat ameboid in appearance Ring appearance usually maintained until late in Developing Trophozoite development Ameboid tendencies not as evident as in P. vivax Progressive dividing chromatin surrounded by cytoplasmic Immature Schizont material, often maintains circular shape early in development Mature Schizont Parasites occupy three quarters of the RBC Rosettes of an average of 8 merozoites Micro/ Macrogametocytes Similar to P. vivax, only smaller in size
A Recapitulation cont’d Plasmodium malariae Typical Characteristics at a Glance Relative age of infected RBCs mature RBCs Appearance of infected RBCs normal size; no distortion (mature cells are not pliable anymore) Morphologic Form Typical Characteristics (based on Giemsa stain) Ring Form smaller in size than P. vivax occupies 1/6 of the RBC heavy chromatin dot vacuole may appear "filled in" pigment forms early Developing Trophozoite Non-ameboid soild cytoplasm that may assume a roundish, oval band, or bar shape Cytoplasm contains coarse dark brown pigment that may mask chromatin material vacuoles are absent in mature stages Immature Schizont Similar to that of P. vivax, only smaller and may contain large and dark peripheral or central granules Mature Schizont 6-12 merozoites arranged in rosettes or irregular clusters central arrangement of brown-green pigment may be visible Macro/ Microgametocyte Similar to P. vivax, only smaller in size and pigment is usually darker and more coarse Older forms assume an oval shape
A Recapitulation cont’d Plasmodium falciparum Typical Characteristics at a Glance Relative age of Infected RBCs May infect cells of all ages Appearance of infected RBCs Normal size; no distortion Morphologic Form Typical characteristics (based on Giemsa stain) Ring Form Circle configuration (one chromatin dot) or headphone configuration (two chromatin dots) Scanty cytoplasm and small vacuole Multiple rings common Accole forms common Developing Trophozoite "heavy rings" common Fine pigment granules Mature forms only seen in severe infections Immature Schizont Multiple chromatin bodies surrrounded by cytoplasm Only detected in severe infections Microgametocyte Sausage or crescent shaped Dispersed central chromatin with nearby black pigment visible Macrogametocyte Sausage or crescent shaped Compact chromatin Black pigment visible
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