Cystoisosporiasis Clinical Presentation

Updated: Mar 07, 2023
  • Author: Venkat R Minnaganti, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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History and Physical Examination

C belli infection is most commonly observed in immunocompromised individuals or in individuals who have recently traveled to tropical areas, in people who are institutionalized, or in persons who live in poor sanitary conditions. The incubation period ranges from 3 to 14 days. Symptoms begin approximately 1 week after ingestion of the oocysts and last 2-3 weeks, with gradual improvement. Infection in people who are immunocompromised may continue indefinitely.

Symptoms and signs may include the following:

  • Profuse, watery, nonbloody, offensive-smelling diarrhea, which may contain mucus
  • Foul-smelling flatus
  • Cramping abdominal pain, vomiting (nausea and vomiting are uncommon)
  • Malaise, anorexia, weight loss
  • Low-grade fever
  • Steatorrhea in protracted cases
  • Myalgias (rare)
  • Headache (rare)

In immunocompromised individuals with severe or long-lasting disease, dehydration may be evident. Otherwise, minimal abdominal tenderness may be present.



Severe dehydration is the most common complication and almost always occurs in patients who are very young or immunocompromised. Acalculous cholecystitis has been reported in patients with AIDS. [8] Tissue invasion and dissemination have been reported on autopsy findings in a few patients with AIDS. Colitis in patients with AIDS has been rarely reported. Reactive arthritis is rare but has been reported in immunocompromised patients.