Cystoisospora belli

From IDWiki
Cystoisospora belli

Background

Epidemiology

  • Worldwide, but more in tropical and subtropical areas
  • Can have outbreaks with daycare, animal exposures
  • Mostly associated with HIV infection, but can also cause a traveller's diarrhea

Life Cycle

  • Oocysts are shed into the environment
    • Each contains one sporoblast
    • Remain viable for months
  • Oocysts sporulate in the environment before becoming infectious
    • Sporoblasts dividing and maturing into two sporocysts, which in turn divide and mature into two sporozoites each
  • The sporulated oocyst (containing four sporozoites) is ingested
  • In the proximal small bowel, the sporozoites are released and develop into merozoites
  • The merozoites go through asexual reproduction, eventually followed by sexual reproduction that results in development of an immature oocyst, which is shed

Clinical Manifestations

  • Incubation period of 1 week
  • Watery diarrhea with abdominal cramping, malaise, anorexia, and weight loss
  • Fever, if it occurs, is low-grade
  • One of the only intestinal protozoa that can cause a peripheral eosinophilia
  • Lasts 2 to 3 weeks, but can continue to shed oocysts for weeks after

Immunocompromised patients

  • Includes HIV (CD4 <200) and chemotherapy
  • Disease course may be more severe and may be chronic
  • Can include hemorrhagic colitis

Management