Cystoisospora belli
From IDWiki
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
- In HIV patients:
- Trimethoprim-sulfamethoxazole DS po qid for 10 days
- Alternative: ciprofloxacin 500 mg po bid for 7 days then three time weekly, pyrimethamine 75 mg po daily with folinic acid, or nitazoxanide
