Amebiasis: Difference between revisions

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==Background==
==Background==
* Fecal oral transmission of Entamoeba histolytica cyst
[[File:Amebiasis LifeCycle.gif|thumb|The life-cycle of various intestinal Entamoeba species.]]
* Excystation in intestinal lumen
*Fecal oral transmission of Entamoeba histolytica cyst
* Trophozoites adhere and colonizes large intestine forming new cysts or invade the intestinal mucosa to cause colitis or abscesses
*Most infection asymptomatic
* Liver abscess-10x more common in men
*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==
==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 [[abdominal pain]], weight loss, watery or bloody [[diarrhea]]
* Liver abscess-fever, cough, and a constant, dull, RUQ or epigastric pain, right-sided pleural pain or referred shoulder pain +/- GI upset
*[[Liver abscess]]-[[fever]], [[cough]], [[RUQ pain|RUQ]] or [[epigastric pain]], right-sided [[chest pain|pleural pain]] or referred shoulder pain +/- GI upset
** Hepatomegaly with tenderness over the liver a typical finding
**[[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- Shigella, Salmonella, Campylobacter, E.Coli.  
*Infectious- [[shigella]], [[salmonella]], [[campylobacter]], [[E. Coli]].  
*Noninfectious- Inflammatory bowel disease, ischemic colitis, diverticulitis, AV malformation.
*Noninfectious- [[Inflammatory bowel disease]], [[ischemic colitis]], [[diverticulitis]], AV malformation.
===Liver abscess===
 
*Pyogenic liver abscess, necrotic hepatoma, Echinococcal cyst
{{Liver abscess DDX}}
==Workup==
 
{{Fever in Traveler DDX}}
 
{{Diarrhea DDX}}
 
==Evaluation==
===Labs===
*CBC
*CBC
*Chem
*Chem
*LFT
*[[LFTs]]
*Stool or abscess microscopy
*Stool PCR
**Diagnostic gold standard
**100% sensitive and specific
*Stool or abscess microscopy  
**<60% SN; unreliable diagnostic test<ref>Rayan HZ. Microscopic overdiagnosis of intestinal amoebiasis. J Egypt Soc Parasitol. 2005;35(3):941–951</ref>
*Stool, serum, or abscess fluid antigen
*Stool, serum, or abscess fluid antigen
*Indirect hemagluttination (antibody)
*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==
==Management==
===Asymptomatic colonization===
===Asymptomatic colonization===
*Paromomycin or Diloxanide
*[[Paromomycin]] or diloxanide
 
===Colitis===
===Colitis===
*Flagyl
*[[Metronidazole]]
 
===Liver abscess===
===Liver abscess===
*Flagyl, Tinidazole, Paromomycin, or Diloxanide
*[[Flagyl]], [[tinidazole]], [[paromomycin]], or diloxanide
*Consider drainage of abscess if no response to abx 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==
*Home if no complications
*'''Admission'''
==Sources==
**Admit if signs of shock, sepsis, or peritonitis
*Haque R, Huston C, Hughes M, Houpt E, Petri, W. ''Amebiasis''. N Engl J Med 2003; 348:1565-1573
**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==
*[https://www.merckmanuals.com/professional/infectious-diseases/intestinal-protozoa-and-microsporidia/amebiasis?query=amebiasis Merk Manual - Amebiasis]
 
==References==
<references/>
 
[[Category:ID]]
[[Category:Tropical Medicine]]
[[Category:GI]]

Latest revision as of 13:21, 24 July 2021

Background

The life-cycle of various intestinal Entamoeba species.
  • 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

Hepatic abscess

Fever in traveler

Acute diarrhea

Infectious

Noninfectious

Watery Diarrhea

Traveler's Diarrhea

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

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

References

  1. ↑ Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.
  2. ↑ Rayan HZ. Microscopic overdiagnosis of intestinal amoebiasis. J Egypt Soc Parasitol. 2005;35(3):941–951
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