Focus on pathogens: Cyclospora cayetanensis

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Focus on pathogens Cyclospora cayetanensis

• Pathology / clinical symptoms sporozoites encyst
  on intestinal microvilli. C. parvum-like
  gatroenteritis prolonged watery diarhea,
  cramping, etc. Duration is 1-4 weeks. Flu-like
  symptoms can accompany the GI symptoms. Mild
  infections can be asymptomatic.
• Like C. parvum, the mechanism of pathogenicity is
  unknown.
• C. parvum-like another source of confusion

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Focus on pathogens Cyclospora cayetanensis

• Laboratory diagnosis - Oocysts
• Size 9uM 1.5-2 X the size of C. parvum
• Appearance spherical-ovoid, refractile, smooth
  wall
• May be viewed with wet mounts, concentrates, and
  modified acid-fast permanent stain like C.
  parvum.
• Distinction made via size with ocular micrometer
  on a good scope.
• Again, not so unlike C. parvum.

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Cyclospora cayetanensis acid-fast oocyst
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Cyclospora vs Cryptosporidium acid-fast stain
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Focus on pathogens Isospora belli

• Facts / life-cycle although this organism was
  described before C. cayetanensis, less is known
  about this guy. The life-cycle is thought to be
  like C. cayetanensis in every way. Like C.
  cayetanensis, it is NOT thought to be a zoonosis.

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Focus on pathogens Isospora belli

• Epidemiology very little known. Infections in
  humans are rare and found mainly in tropical
  regions.

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Focus on pathogens Isospora belli

• Pathology / clinical symptoms
• Most infections are asymptomatic and self-limited
• Symptomatic disease in immune competent
  individuals includes diarrhea and malabsorption
• AIDS patients have severe persistent diarrhea
  that leads to dehydration and electrolyte
  imbalance, which can be fatal
• Mucosal epithelial cells in which I. belli
  develop rupture when the organsims are released
  creating the symptoms described above

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Focus on pathogens Isospora belli

• Laboratory diagnosis of oocysts in stool
• Size 12x30 ?m
• Shape Oval
• Morphology Clear cyst wall (no staining
  required) with one or two spherical cell-like
  inclusions which stain red in an acid fast stain

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Isospora belli oocysts
Iodine wet mounts permanent stain