The Three Faces of Eve

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The Three Faces of Eve

• Special ID Grand Rounds, 4/5/12
• Ambar Haleem, MD, Infectious Disease
• Paola Boggiato, Postdoc, Microbiology

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Case- part I (2009)

• CC Bloody diarrhea
• HPI 33 M with 10mth h/o daily bloody, mucoid
  diarrhea, with fecal urgency, tenesmus,
  abdominal tenderness.
• ROS Fatigue, dizziness, anorexia, 30lb wt loss.
• SH Immigrant from Sudan. No h/o () TB test or
  incarceration. Not sexually active.
• EXAM Afebrile, Orthostatic.
• LABS Hb 7.5g/dl, plt 508. Wbc, renal liver fxn
  NL.

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Part I diagnostic evaluation

• Stool assays for bacteria, ova parasites NEG.
• Quantiferon TB Gold and HIV serology NEG.
• E histolytica serology and stool Ag by EIA NEG
• CT abd Thickened L-sided bowel wall with fat
  stranding, () LN.
• Barium enema Granular mucosa, L-sided colonic
  ulcers, possible stricture at junction of
  rectosigmoid and descending colon
• Colonoscopy Severe left-sided colitis, cecal and
  peri-appendiceal inflammation with
  superficial rectal ulcers

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Part I diagnosis outcome

• Histopathology Severe colitis, cryptitis, crypt
  abscesses and Entamoeba cysts
• Treatment Metronidazole x 14d iodoquinol x
  20d Excellent clinical response.
• No similar history in household members
• Parents' stool OP test negative for amoebic
  cysts.

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Case- part II (2011)

• Similar clinical presentation as in 2009, with 2
  wk symptom duration
• Entamoeba serology and E histolytica stool Ag
  again negative
• Colonoscopy Severe L-sided colitis, punctate
  ulcers scattered b/w areas of normal colonic
  mucosa. No organisms seen.
• Treatment Metronidazole x 21 d and paromomycin x
  10d --- Excellent clinical response.

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Histopathology- Normal colon
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2009 colon biopsies
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2009 colon biopsies
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2011 colon biopsy and 2012 appendectomy
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Epidemiology of Amoebiasis

• Worldwide prevalence of Entamoeba infections is
  10 of the population
• Entamoeba taxonomy
• E. histolytica - pathogenic sp.
• E. dispar, E. moskovsksii- nonpathogenic sp.
• True prevalence and incidence of E. histolytica
  not well-established
• Approx. 50 million people infected annually
• gt90 E. histolytica infections are asymptomatic

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Epidemiology of Amoebiasis

• E. histolytica infections cause death in
  100,000 people worldwide/year
• In the US, combined prevalence of E.
  histolytica/E. dispar 4
• Humans are the only reservoir
• Fecal-oral transmission (main route)
• Asymptomatic cyst passers (E. dispar, E.
  histolytica)
• Colonization with E. histolytica is associated
  with development of invasive amebiasis

S Afr Med J 198772, JID 2002 86 CID 2012 54
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Amoebae- morphology
Trophozoite of E. histolytica
Cysts of E. histolytica / E. dispar stained with
trichrome. Nuclei (black arrows) Chromatoid
bodies with typically blunted ends (red arrows)

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E. histolytica disease

• Clinical syndromes
• Asymptomatic intestinal colonisation
• Intestinal amoebiasis
• Extra-intestinal disease
• Chronic, nondysenteric, amoebiasis

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CID 199929
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Sensitivity of tests for diagnosis of Amoebiasis
Serology by ELISA most popular method,
recommended by CDC
NEJM 2003 348
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Differences in disease expression by geography,
age, gender, parasite virulence and host and
parasite genetics
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• QUESTIONS
• 1. What determines the switch of E. histolytica
  from an asymptomatic coloniser to a pathogenic
  phenotype?
•  
• 2. Is there a link between amoebiasis and
  inflammatory bowel disease?
• 3. Does E. histolytica induce any protective
• immunity? If so, are there potential vaccine
• candidates?