Podcast
Questions and Answers
Match the parasite with its characteristic size range for trophozoites:
Match the parasite with its characteristic size range for trophozoites:
Endolimax nana = 8 to 12μm Entamoeba histolytica = 12 to 55μm Entamoeba polecki = 18 to 27μm Entamoeba hartmanni = 12 to 55μm
Match the parasite with its characteristic motility for trophozoites:
Match the parasite with its characteristic motility for trophozoites:
Entamoeba coli = Sluggish, nonprogressive Entamoeba gingivalis = Rapid and jerky Acanthamoeba species = Flagellated Naegleria fowleri = Ciliated
Match the parasite with the description of its cysts:
Match the parasite with the description of its cysts:
Entamoeba histolytica = Thick cell wall surrounds the round to spherical cyst Entamoeba polecki = Thin delicate cyst wall Iodamoeba butschlii = Usually uninucleate Endolimax nana = One to eight nuclei with typical nuclear features
Match the parasite with its typical life cycle location in stool:
Match the parasite with its typical life cycle location in stool:
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Match the parasite with its pathogenicity status:
Match the parasite with its pathogenicity status:
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Match the parasite with its importance in medical diagnosis:
Match the parasite with its importance in medical diagnosis:
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Match the following characteristics with Entamoeba histolytica:
Match the following characteristics with Entamoeba histolytica:
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Match the following parasites with their size range in micrometers:
Match the following parasites with their size range in micrometers:
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Match the following characteristics with Acanthamoeba species:
Match the following characteristics with Acanthamoeba species:
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Match the following parasites with their clinical significance:
Match the following parasites with their clinical significance:
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Match the following parasites with their characteristics related to pseudopods:
Match the following parasites with their characteristics related to pseudopods:
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Match the following parasites with their treatment options:
Match the following parasites with their treatment options:
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Match the following amoeba with their characteristics:
Match the following amoeba with their characteristics:
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Match the following amoeba with their sizes:
Match the following amoeba with their sizes:
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Match the following amoeba with their life cycle stages:
Match the following amoeba with their life cycle stages:
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Match the following amoeba with their treatment options:
Match the following amoeba with their treatment options:
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Match the following amoeba with their clinical symptoms:
Match the following amoeba with their clinical symptoms:
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Match the following amoeba with their motility characteristics:
Match the following amoeba with their motility characteristics:
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Study Notes
Phylum Sarcomastigophora
- Amoeba is a single-celled protozoa that constantly changes its shape due to the presence of pseudopodia.
- The word "amoeba" is derived from the Greek word "amoibe," meaning "change."
Entamoeba histolytica
- Discovered by Loschin in 1875.
- Found in the dysenteric feces of a patient in St. Petersburg, Russia.
- Named and differentiated from E. coli by Fritz Schaudinn.
- Anaerobic parasitic amoebozoan that infects humans and other primates, causing amoebiasis.
- Estimated to infect about 50 million people worldwide.
Morphology of Entamoeba histolytica
- Trophozoites:
- Range in size from 12 to 60μm, with an average size of 12 to 25μm.
- Exhibit rapid, unidirectional, progressive movement.
- Have finger-like hyaline pseudopods.
- Single nucleus contains a small karyosome.
- Cysts:
- Spherical to round in shape.
- Smaller than trophozoites, measuring 8 to 22μm, with an average range of 12 to 18μm.
Laboratory Diagnosis and Clinical Significance
- Stool examination for trophozoites and cysts.
- Asymptomatic infections are common.
- Treatment: nitroimidazole for intestinal infection, metronidazole and chloroquine for liver abscess.
Entamoeba coli
- Nonpathogenic species of Entamoeba.
- Frequently exists as a commensal parasite in the human gastrointestinal tract.
- Can be confused with Entamoeba histolytica during microscopic examination.
Morphology of Entamoeba coli
- Trophozoites:
- Measure between 18 to 27μm, with some as small as 12μm and others as large as 55μm.
- Equipped with blunt pseudopods.
- Exhibit sluggish, nonprogressive motility.
- Cysts:
- Vary in size from 8 to 35μm, with an average of 12 to 25μm.
- Thick cell wall surrounds the round to spherical cyst.
- One to eight nuclei with typical nuclear features.
Life Cycle of Entamoeba coli
- Cysts are typically found in formed stool, while trophozoites are typically found in diarrheal stool.
- Intestinal colonization occurs after ingestion of mature cysts in fecally contaminated food, water, or fomites.
- More often, the amoeba penetrates the submucosal layer and multiplies rapidly, causing lytic necrosis, abscess, and ulcer.
Entamoeba hartmanni
- Nonpathogenic amoeba with worldwide distribution.
- Life cycle similar to Entamoeba histolytica but lacks an invasive stage and does not ingest red blood cells.
Morphology of Entamoeba hartmanni
- Trophozoites:
- Measure 8 to 12μm, with a range of 5 to 15μm.
- Finger-shaped pseudopods exhibiting nonprogressive motility.
- Contain one nucleus with peripheral chromatin.
- Cysts:
- Range in size from 5 to 12μm, with an average size of 7 to 9μm.
- Spherical cysts may have one, two, three, or four nuclei.
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Description
Learn about the clinical symptoms, treatment options, and different types of amebiasis caused by Entamoeba histolytica. Understand the manifestations such as asymptomatic carrier state, symptomatic intestinal amebiasis, and extraintestinal amebiasis.