Small intestine & ampulla
Infectious disorders
Isospora belli

Topic Completed: 1 August 2012

Minor changes: 15 September 2020

Copyright: 2003-2021,, Inc.

PubMed Search: Isospora belli small bowel

Hanni Gulwani, M.B.B.S.
Page views in 2020: 1,571
Page views in 2021 to date: 548
Cite this page: Gulwani H. Isospora belli. website. Accessed May 7th, 2021.
Definition / general
  • Coccidian parasite that infects epithelial cells of small intestine
  • Causes chronic diarrhea and acalculous cholecystitis in AIDS patients (Indian J Med Res 2011;134:878)
Diagrams / tables

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Life cycle

  • Cysts in stool, biopsy (H&E or EM)
Case reports
Microscopic (histologic) description
  • Cysts present in parasitophorous vacuole in lamina propria (Hum Pathol 2001;32:500)
  • Ovoid developmental forms are identified in and beneath epithelial cells near villus tip
Microscopic (histologic) images

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Oocyst of C. belli in epithelial cells of mammalian host

Isospora belli (20 - 30 μm
long by 10 - 19 μm wide)
- immature oocyst
(modified acid fast stain)

Positive stains
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