Microsporidiosis pathophysiology

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [2] Ahmed Younes M.B.B.CH [3]

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Overview

Microsporidia are a group of obligate intracellular protozoa with more than 1,200 species belonging to 143 genera that infect a wide range of vertebrate and invertebrate hosts. They are characterized by the production of resistant spores that vary in size, depending on the species. After ingestion, it infects intestinal epithelial cells and causes chronic diarrhea with the possibility of distant spread. The microorganism can be visualized in stool samples using "Quick-Hot Gram Chromotrope technique".

Pathophysiology

Life Cycle

The infective form of microsporidia is the resistant spore and it can survive for an extended period of time in the environment.[1]

Life cycle of microsporoidosia https://commons.wikimedia.org/w/index.php?curid=2740681
  1. The spores enter the body via ingestion or inhalation.
  2. Spores penetrate host cell using its polar tubule.
  3. The spore uses its polar tubule for injecting its sarcoplasm into the infected cell.
  4. The sarcoplasm multiplies either by binary fission or multiple fission
  5. The sarcoplasm of microsporidia develops into mature spores either free in the cytoplasm or inside a vacuole.
  6. The process of development involves acquiring a thick capsule. This capsule provides protection against environmental stressors and is thought to play a role in its infectivity.
  7. After their number reaches a certain limit, the host cell ruptures releasing the spores to continue the life cycle.

Pathogenesis

Microscopic pathology

  • Intestinal biopsy shows crypt hyperplasia and decreases in the absorptive surface of the intestine.[2]
  • Stool examination using “Quick-Hot Gram Chromotrope technique” reveals the spores staining dark violet and containing gram-positive granules.
  • Enterocytozoon bieneusi spores measure 0.8 - 1.4 µm while spores of Anncaliia algerae, Encephalitozoon spp., Vittaforma corneae, and Nosema spp measure 1.5 - 4 µm.

References

  1. "CDC - DPDx - Microsporidiosis".
  2. 2.0 2.1 Franzen C, Müller A (2001). "Microsporidiosis: human diseases and diagnosis". Microbes Infect. 3 (5): 389–400. PMID 11369276.
  3. Weber R, Bryan RT, Schwartz DA, Owen RL (1994). "Human microsporidial infections". Clin. Microbiol. Rev. 7 (4): 426–61. PMC 358336. PMID 7834600.