Amebiasis

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, and a constant, dull, 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.

Liver abscess

• Pyogenic liver abscess, necrotic hepatoma, Echinococcal cyst

Workup

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

Management

Asymptomatic colonization

• Paromomycin or Diloxanide

Colitis

• Flagyl

Liver abscess

• Flagyl, Tinidazole, Paromomycin, or Diloxanide
• Consider drainage of abscess if no response to abx in 5 days, abscess >5cm or left lobe involvement

Disposition

• Home if no complications

Sources

• Haque R, Huston C, Hughes M, Houpt E, Petri, W. Amebiasis. N Engl J Med 2003; 348:1565-1573