Amebiasis: Difference between revisions
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==Background== | ==Background== | ||
[[File:Amebiasis LifeCycle.gif|thumb|The life-cycle of various intestinal Entamoeba species.]] | [[File:Amebiasis LifeCycle.gif|thumb|The life-cycle of various intestinal Entamoeba species.]] | ||
*Fecal oral transmission of Entamoeba histolytica cyst | *Fecal oral transmission of Entamoeba histolytica cyst | ||
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*Excystation in intestinal lumen | *Excystation in intestinal lumen | ||
*Trophozoites adhere and colonizes large intestine forming new cysts or invade the intestinal mucosa to cause colitis or abscesses | *Trophozoites adhere and colonizes large intestine forming new cysts or invade the intestinal mucosa to cause colitis or abscesses | ||
*[[Liver abscess]] - 10x more common in men | *[[Special:MyLanguage/Liver abscess|Liver abscess]] - 10x more common in men | ||
*Incubation period usually 2-4 weeks, but may range from a few days to years | *Incubation period usually 2-4 weeks, but may range from a few days to years | ||
==Clinical Features== | ==Clinical Features== | ||
*Asymptomatic vs. dysentery vs. extraintestinal abscesses | *Asymptomatic vs. dysentery vs. extraintestinal abscesses | ||
*Intestinal- several weeks of crampy [[abdominal pain]], weight loss, watery or bloody [[diarrhea]] | *Intestinal- several weeks of crampy [[Special:MyLanguage/abdominal pain|abdominal pain]], weight loss, watery or bloody [[Special:MyLanguage/diarrhea|diarrhea]] | ||
*[[Liver abscess]]-[[fever]], [[cough]], [[RUQ pain|RUQ]] or [[epigastric pain]], right-sided [[chest pain|pleural pain]] or referred shoulder pain +/- GI upset | *[[Special:MyLanguage/Liver abscess|Liver abscess]]-[[Special:MyLanguage/fever|fever]], [[Special:MyLanguage/cough|cough]], [[Special:MyLanguage/RUQ pain|RUQ]] or [[Special:MyLanguage/epigastric pain|epigastric pain]], right-sided [[Special:MyLanguage/chest pain|pleural pain]] or referred shoulder pain +/- GI upset | ||
**[[Hepatomegaly]] with tenderness over the liver a typical finding | **[[Special:MyLanguage/Hepatomegaly|Hepatomegaly]] with tenderness over the liver a typical finding | ||
**Abscess rupture can involve associated peritoneum, pericardium, or pleural cavity | **Abscess rupture can involve associated peritoneum, pericardium, or pleural cavity | ||
*Extrahepatic amebic abscesses in the lung, brain, and skin are rare | *Extrahepatic amebic abscesses in the lung, brain, and skin are rare | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
===Dysentery=== | ===Dysentery=== | ||
*Infectious- [[Special:MyLanguage/shigella|shigella]], [[Special:MyLanguage/salmonella|salmonella]], [[Special:MyLanguage/campylobacter|campylobacter]], [[Special:MyLanguage/E. Coli|E. Coli]]. | |||
*Noninfectious- [[Special:MyLanguage/Inflammatory bowel disease|Inflammatory bowel disease]], [[Special:MyLanguage/ischemic colitis|ischemic colitis]], [[Special:MyLanguage/diverticulitis|diverticulitis]], AV malformation. | |||
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{{Liver abscess DDX}} | {{Liver abscess DDX}} | ||
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{{Fever in Traveler DDX}} | {{Fever in Traveler DDX}} | ||
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{{Diarrhea DDX}} | {{Diarrhea DDX}} | ||
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==Evaluation== | ==Evaluation== | ||
===Labs=== | ===Labs=== | ||
*CBC | *CBC | ||
*Chem | *Chem | ||
*[[LFTs]] | *[[Special:MyLanguage/LFTs|LFTs]] | ||
*Stool PCR | *Stool PCR | ||
**Diagnostic gold standard | **Diagnostic gold standard | ||
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*Stool, serum, or abscess fluid antigen | *Stool, serum, or abscess fluid antigen | ||
*Indirect hemagglutination (antibody) | *Indirect hemagglutination (antibody) | ||
===Imaging=== | ===Imaging=== | ||
*Abdominal Ultrasound | *Abdominal Ultrasound | ||
**58-98% SN for liver abscess (depending on size/location) | **58-98% SN for liver abscess (depending on size/location) | ||
*Abdominal CT | *Abdominal CT | ||
**Alternative to ultrasound; equally effective in identifying abscess | **Alternative to ultrasound; equally effective in identifying abscess | ||
==Management== | ==Management== | ||
===Asymptomatic colonization=== | ===Asymptomatic colonization=== | ||
*[[Paromomycin]] or diloxanide | |||
*[[Special:MyLanguage/Paromomycin|Paromomycin]] or diloxanide | |||
===Colitis=== | ===Colitis=== | ||
*[[Metronidazole]] | |||
*[[Special:MyLanguage/Metronidazole|Metronidazole]] | |||
===Liver abscess=== | ===Liver abscess=== | ||
*[[Flagyl]], [[tinidazole]], [[paromomycin]], or diloxanide | |||
*[[Special:MyLanguage/Flagyl|Flagyl]], [[Special:MyLanguage/tinidazole|tinidazole]], [[Special:MyLanguage/paromomycin|paromomycin]], or diloxanide | |||
*Consider drainage of abscess by IR if no response to antibiotics in 5 days, abscess > 5cm, or left lobe involvement | *Consider drainage of abscess by IR if no response to antibiotics in 5 days, abscess > 5cm, or left lobe involvement | ||
==Disposition== | ==Disposition== | ||
*'''Admission''' | *'''Admission''' | ||
**Admit if signs of shock, sepsis, or peritonitis | **Admit if signs of shock, sepsis, or peritonitis | ||
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*'''Discharge''' | *'''Discharge''' | ||
**Patients who are non-toxic and able to tolerate oral hydration/PO meds can be discharged with outpatient follow-up | **Patients who are non-toxic and able to tolerate oral hydration/PO meds can be discharged with outpatient follow-up | ||
==External Links== | ==External Links== | ||
*[https://www.merckmanuals.com/professional/infectious-diseases/intestinal-protozoa-and-microsporidia/amebiasis?query=amebiasis Merk Manual - Amebiasis] | *[https://www.merckmanuals.com/professional/infectious-diseases/intestinal-protozoa-and-microsporidia/amebiasis?query=amebiasis Merk Manual - Amebiasis] | ||
==References== | ==References== | ||
<references/> | <references/> | ||
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[[Category:Tropical Medicine]] | [[Category:Tropical Medicine]] | ||
[[Category:GI]] | [[Category:GI]] | ||
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Revision as of 21:37, 4 January 2026
Background
- Fecal oral transmission of Entamoeba histolytica cyst
- Most infection asymptomatic
- Excystation in intestinal lumen
- Trophozoites adhere and colonizes large intestine forming new cysts or invade the intestinal mucosa to cause colitis or abscesses
- Liver abscess - 10x more common in men
- Incubation period usually 2-4 weeks, but may range from a few days to years
Clinical Features
- Asymptomatic vs. dysentery vs. extraintestinal abscesses
- Intestinal- several weeks of crampy abdominal pain, weight loss, watery or bloody diarrhea
- Liver abscess-fever, cough, RUQ or epigastric pain, right-sided pleural pain or referred shoulder pain +/- GI upset
- Hepatomegaly with tenderness over the liver a typical finding
- Abscess rupture can involve associated peritoneum, pericardium, or pleural cavity
- Extrahepatic amebic abscesses in the lung, brain, and skin are rare
Differential Diagnosis
Dysentery
- Infectious- shigella, salmonella, campylobacter, E. Coli.
- Noninfectious- Inflammatory bowel disease, ischemic colitis, diverticulitis, AV malformation.
Hepatic abscess
- Pyogenic abscess
- Aerobic: Escherichia coli, Klebsiella, Pseudomonas
- Anaerobic: Enterococcus, bacteroides, anaerobic streptococci
- Echinococcosis
- Amebiasis
- Benign cysts/malignancy
- Tuberculosis
- Mycosis
Fever in traveler
- Normal causes of acute fever!
- Malaria
- Dengue
- Leptospirosis
- Typhoid fever
- Typhus
- Viral hemorrhagic fevers
- Chikungunya
- Yellow fever
- Rift valley fever
- Q fever
- Amebiasis
- Zika virus
Acute diarrhea
Infectious
- Viral (e.g. rotavirus)
- Bacterial
- Campylobacter
- Shigella
- Salmonella (non-typhi)
- Escherichia coli
- E. coli 0157:H7
- Yersinia enterocolitica
- Vibrio cholerae
- Clostridium difficile
- Parasitic
- Toxin
Noninfectious
- GI Bleed
- Appendicitis
- Mesenteric Ischemia
- Diverticulitis
- Adrenal Crisis
- Thyroid Storm
- Toxicologic exposures
- Antibiotic or drug-associated
- Inflammatory bowel disease
Watery Diarrhea
- Enterotoxigenic E. coli (most common cause of watery diarrhea)[1]
- Norovirus (often has prominent vomiting)
- Campylobacter
- Non-typhoidal Salmonella
- Enteroaggregative E. coli (EAEC)
- Enterotoxigenic Bacteroides fragilis
Traveler's Diarrhea
- Giardia lamblia
- Cryptosporidiosis
- Entamoeba histolytica
- Cyclospora
- Clostridium perfringens
- Listeriosis
- Helminth infections
- Marine toxins
- Ciguatera
- Scombroid poisoning
- Paralytic shellfish poisoning
- Neurotoxic shellfish poisoning
- Diarrheal shellfish poisoning
Evaluation
Labs
- CBC
- Chem
- LFTs
- Stool PCR
- Diagnostic gold standard
- 100% sensitive and specific
- Stool or abscess microscopy
- <60% SN; unreliable diagnostic test[2]
- Stool, serum, or abscess fluid antigen
- Indirect hemagglutination (antibody)
Imaging
- Abdominal Ultrasound
- 58-98% SN for liver abscess (depending on size/location)
- Abdominal CT
- Alternative to ultrasound; equally effective in identifying abscess
Management
Asymptomatic colonization
- Paromomycin or diloxanide
Colitis
Liver abscess
- Flagyl, tinidazole, paromomycin, or diloxanide
- Consider drainage of abscess by IR if no response to antibiotics in 5 days, abscess > 5cm, or left lobe involvement
Disposition
- Admission
- Admit if signs of shock, sepsis, or peritonitis
- Patients with toxic megacolon should be admitted for surgical intervention.
- Discharge
- Patients who are non-toxic and able to tolerate oral hydration/PO meds can be discharged with outpatient follow-up
External Links