Amebiasis

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Background

  • Fecal oral transmission of Entamoeba histolytica cyst
  • 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

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

  • 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

Evaluation

  • CBC
  • Chem
  • LFT
  • Stool or abscess microscopy
  • Stool, serum, or abscess fluid antigen
  • Indirect hemagluttination (antibody)
  • CT or ultrasound for suspected abscess

Management

Asymptomatic colonization

Colitis

Liver abscess

  • Flagyl, tinidazole, paromomycin, or diloxanide
  • Consider drainage of abscess if no response to antibiotics in 5 days, abscess > 5cm, or left lobe involvement

Disposition

  • Home if no complications

References

  1. Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.