Amebiasis

==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

==Differential Diagnosis== ===Dysentery=== *Infectious- shigella, salmonella, campylobacter, E. Coli.

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=== *Paromomycin or diloxanide

Colitis

===Liver abscess=== *Metronidazole, 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== *Merk Manual - Amebiasis

==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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