Entamoeba histolytica: Difference between revisions
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Entamoeba histolytica
(Created page with "* Intestinal protozoan parasite * Causes amebic dysentery * Microscopically distinguishable from the non-pathogenic ''E. dispar'', so needs molecular tests to confirm diagnosi...") Â |
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+ | ==Background== |
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− | * Intestinal protozoan parasite |
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+ | ===Microbiology=== |
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− | * Causes amebic dysentery |
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⚫ | |||
+ | *Intestinal protozoan parasite within the genus ''[[Entamoeba species|Entamoeba]]'' |
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+ | *Microscopically distinguishable from the non-pathogenic ''E. dispar'', ''E. moshkovskii'', and ''E. bangladeshii'' |
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+ | |||
+ | ===Epidemiology=== |
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+ | |||
+ | *Present worldwide, but most disease occurs in the developing world |
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+ | *Causes 34 to 50 million cases annually and up to 100,000 deaths |
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+ | |||
+ | ==Clinical Manifestations== |
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+ | ===Amoebic Diarrhea and Dysentery=== |
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+ | |||
+ | *[[Causes::Amoebic diarrhea]], with or without dysentery, is common |
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+ | **About 15 to 30% of cases involve [[Causes::amoebic dysentery]] (with macroscopic or microscopic blood) |
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+ | *Typically a subacute onset over 3 to 4 weeks and abdominal pain |
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+ | **However, can be up to months |
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+ | *Fever is rare, even in dysentery |
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+ | *In children, can lead to intussusception, perforation, and necrotizing colitis |
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+ | |||
+ | ===Amoebic Liver Abscess=== |
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+ | |||
+ | *[[Causes::Amoebic liver abscess]] is far more common in men than women, and rare in children |
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+ | *Symptoms progress over 2 to 4 weeks, with [[fever]] (80%) and [[abdominal pain]] (80%) |
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+ | **Right upper quadrant tenderness (75%), weight loss (40%), diarrhea (15-35%), cough (10%), and jaundice (10-15%) |
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+ | **The pain is typically a dull ache in the right upper quadrant or epigastrium |
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+ | *More likely to present with abdominal pain and right upper quadrant tenderness than [[pyogenic liver abscess]] |
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+ | |||
+ | ===Disseminated Amoebiasis=== |
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+ | |||
+ | *Metastatic infections are possible, most often from direct extension of a liver abscess |
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+ | *Most commonly spreads to chest, with empyema, bronchohepatic fistula, pericarditis |
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+ | *Cerebral disease is rare but can happen |
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+ | |||
+ | ==Diagnosis== |
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+ | |||
⚫ | |||
+ | *On aspiration, the fluid is classically odorless, thick, yellow-brown liquid, described as "anchovy paste" |
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+ | |||
+ | ==Management== |
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+ | |||
+ | === Diarrhea or Dysentery === |
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+ | *Either |
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+ | **[[Is treated by::Metronidazole]] 750 mg p.o. tid for 5 to 10 days |
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+ | **[[Is treated by::Tinidazole]] 2 g PO daily for 3-5 days |
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+ | *Followed by a luminal agent, as below |
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+ | ===Liver Abscess=== |
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+ | |||
+ | *Either |
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+ | **[[Is treated with::Metronidazole]] 750 mg PO tid for 10 days, or |
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+ | **[[Is treated with::Tinidazole]] 2 g PO daily for 5 days |
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+ | *Followed by a luminal agent: |
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+ | **[[Is treated by::Paramomycin]] 500 mg p.o. tid for 7 days |
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+ | **[[Is treated by::Iodoquinol]] 650 mg p.o. tid for 20 days |
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+ | **[[Is treated by::Diloxanide furoate]] 500 mg p.o. tid for 10 days |
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+ | *May need surgery or aspiration if the lesion is large or medication has failed |
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+ | |||
+ | ===Asymptomatic Carriage=== |
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+ | |||
+ | *Treat with a luminal agent, as above |
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+ | |||
+ | === Treatments in Canada === |
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+ | |||
+ | * Metronidazole, iodoquinol, and paromomycin are all available in Canada |
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+ | |||
+ | == Further Reading == |
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+ | |||
+ | * Adrienne J. Showler, Andrea K. Boggild. Entamoeba histolytica. <abbr>''CMAJ''</abbr> Sep 2013, 185 (12) 1064; '''DOI:''' [https://doi.org/10.1503/cmaj.121576 10.1503/cmaj.121576]{{DISPLAYTITLE:''Entamoeba histolytica''}} |
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[[Category:Protozoa]] |
[[Category:Protozoa]] |
Latest revision as of 09:43, 7 October 2023
Background
Microbiology
- Intestinal protozoan parasite within the genus Entamoeba
- Microscopically distinguishable from the non-pathogenic E. dispar, E. moshkovskii, and E. bangladeshii
Epidemiology
- Present worldwide, but most disease occurs in the developing world
- Causes 34 to 50 million cases annually and up to 100,000 deaths
Clinical Manifestations
Amoebic Diarrhea and Dysentery
- Amoebic diarrhea, with or without dysentery, is common
- About 15 to 30% of cases involve amoebic dysentery (with macroscopic or microscopic blood)
- Typically a subacute onset over 3 to 4 weeks and abdominal pain
- However, can be up to months
- Fever is rare, even in dysentery
- In children, can lead to intussusception, perforation, and necrotizing colitis
Amoebic Liver Abscess
- Amoebic liver abscess is far more common in men than women, and rare in children
- Symptoms progress over 2 to 4 weeks, with fever (80%) and abdominal pain (80%)
- Right upper quadrant tenderness (75%), weight loss (40%), diarrhea (15-35%), cough (10%), and jaundice (10-15%)
- The pain is typically a dull ache in the right upper quadrant or epigastrium
- More likely to present with abdominal pain and right upper quadrant tenderness than pyogenic liver abscess
Disseminated Amoebiasis
- Metastatic infections are possible, most often from direct extension of a liver abscess
- Most commonly spreads to chest, with empyema, bronchohepatic fistula, pericarditis
- Cerebral disease is rare but can happen
Diagnosis
- Microscopically indistinguishable from the non-pathogenic E. dispar, so needs molecular tests to confirm diagnosis
- On aspiration, the fluid is classically odorless, thick, yellow-brown liquid, described as "anchovy paste"
Management
Diarrhea or Dysentery
- Either
- Metronidazole 750 mg p.o. tid for 5 to 10 days
- Tinidazole 2 g PO daily for 3-5 days
- Followed by a luminal agent, as below
Liver Abscess
- Either
- Metronidazole 750 mg PO tid for 10 days, or
- Tinidazole 2 g PO daily for 5 days
- Followed by a luminal agent:
- Paramomycin 500 mg p.o. tid for 7 days
- Iodoquinol 650 mg p.o. tid for 20 days
- Diloxanide furoate 500 mg p.o. tid for 10 days
- May need surgery or aspiration if the lesion is large or medication has failed
Asymptomatic Carriage
- Treat with a luminal agent, as above
Treatments in Canada
- Metronidazole, iodoquinol, and paromomycin are all available in Canada
Further Reading
- Adrienne J. Showler, Andrea K. Boggild. Entamoeba histolytica. CMAJ Sep 2013, 185 (12) 1064; DOI: 10.1503/cmaj.121576