Amebiasis: Difference between revisions
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==Background== | ==Background== <!--T:1--> | ||
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[[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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==Clinical Features== | ==Clinical Features== <!--T:3--> | ||
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*Asymptomatic vs. dysentery vs. extraintestinal abscesses | *Asymptomatic vs. dysentery vs. extraintestinal abscesses | ||
*Intestinal- several weeks of crampy [[Special:MyLanguage/abdominal pain|abdominal pain]], weight loss, watery or bloody [[Special:MyLanguage/diarrhea|diarrhea]] | *Intestinal- several weeks of crampy [[Special:MyLanguage/abdominal pain|abdominal pain]], weight loss, watery or bloody [[Special:MyLanguage/diarrhea|diarrhea]] | ||
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==Differential Diagnosis== | ==Differential Diagnosis== <!--T:5--> | ||
===Dysentery=== | ===Dysentery=== <!--T:6--> | ||
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*Infectious- [[Special:MyLanguage/shigella|shigella]], [[Special:MyLanguage/salmonella|salmonella]], [[Special:MyLanguage/campylobacter|campylobacter]], [[Special:MyLanguage/E. Coli|E. Coli]]. | *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. | *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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==Evaluation== | ==Evaluation== <!--T:8--> | ||
===Labs=== | ===Labs=== <!--T:9--> | ||
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*CBC | *CBC | ||
*Chem | *Chem | ||
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===Imaging=== | ===Imaging=== <!--T:11--> | ||
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*Abdominal Ultrasound | *Abdominal Ultrasound | ||
**58-98% SN for liver abscess (depending on size/location) | **58-98% SN for liver abscess (depending on size/location) | ||
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==Management== | ==Management== <!--T:13--> | ||
===Asymptomatic colonization=== | ===Asymptomatic colonization=== <!--T:14--> | ||
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*[[Special:MyLanguage/Paromomycin|Paromomycin]] or diloxanide | *[[Special:MyLanguage/Paromomycin|Paromomycin]] or diloxanide | ||
===Colitis=== | ===Colitis=== <!--T:16--> | ||
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*[[Special:MyLanguage/Metronidazole|Metronidazole]] | *[[Special:MyLanguage/Metronidazole|Metronidazole]] | ||
===Liver abscess=== | ===Liver abscess=== <!--T:18--> | ||
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*[[Special:MyLanguage/Flagyl|Flagyl]], [[Special:MyLanguage/tinidazole|tinidazole]], [[Special:MyLanguage/paromomycin|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 | ||
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==Disposition== | ==Disposition== <!--T:20--> | ||
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*'''Admission''' | *'''Admission''' | ||
**Admit if signs of shock, sepsis, or peritonitis | **Admit if signs of shock, sepsis, or peritonitis | ||
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==External Links== | ==External Links== <!--T:22--> | ||
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*[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== <!--T:24--> | ||
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<references/> | <references/> | ||
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[[Category:ID]] | [[Category:ID]] | ||
[[Category:Tropical Medicine]] | [[Category:Tropical Medicine]] | ||
Latest revision as of 20:29, 6 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