Microsporidium

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Background

Microsporidia are unicellular spore-forming parasitic protozoa that are found pervasively throughout the environment.[1] Microsporidiosis most commonly affects immunosuppressed individuals and seldom has implications for the immunocompetent patient.

Clinical Features

Clinical manifestations are wide ranging and typically affect immunosuppressed hosts (e.g. HIV/AIDS, long-term steroid use, transplant and chemotherapy patients), travelers, children, and the elderly[2]. The most common manifestation is copious diarrhea with volume depletion leading to electrolyte derangements.[3]

Immunosuppressed patients:[4]

  • Profuse watery diarrhea with massive fluid loss
  • Cholangitis and acalculous cholecystitis
  • Disseminated infection
  • Myositis

Immunocompetent patients:[5]

  • Self-limited diarrhea

Differential Diagnosis

  • Microsporidiosis
  • Cryptosporidiosis
  • CMV (CD4 < 100)
  • MAC (CD4 < 100)
  • Adenovirus
  • Isospora
  • Giardia
  • E. coli
  • C. difficile

Evaluation

Work-up

  • CBC
  • Metabolic panel
  • C. difficile toxin EIA
  • Fecal WBC and RBC
  • Lactoferrin
  • Wet mount microscopy
  • Stool culture

Evaluation

  • It is important to differentiate bloody vs non-bloody and acute vs chronic diarrhea. Additionally helpful information includes recent antibiotic use, history of C. difficile, presence of nausea, vomiting, fevers, altered mental status, severe abdominal pain, and whether their diarrhea is distracting them from an additional problem.

Management[6]

  • Initial treatment consists of the ABCs
    • IV fluid resuscitation with LR or NS (bolus 500 mL adults, 20/30 mL/kg in children)
    • Oral rehydrating solution for mild dehydration and tolerating PO intake (WHO advocates 250 mL orange juice, 4 tsp sugar, 1 tsp baking powder, 3.75 mL salt in 1 L of boiled water. Goal is 50-100 mL/kg over the first 4 hours)
    • Address electrolyte derangements
  • Albendazole 400 mg PO bid for 14-28 days in adults (15mg/kg PO bid for 7 days in children)
  • Ondansetron or promethazine for nausea (avoid metoclopramide due to pro-motility effects)
  • Loperamide for symptom reduction (contraindicated with bloody stool)

Disposition[7]

  • Discharge: immunocompetent or low risk patients with unclear etiology but normal examination findings after rehydration
  • Admission: patients with life-threatening volume loss, failure to improve after resuscitation, electrolyte abnormalities requiring gradual and/or significant correction, toxic or ill-appearing, intolerant of PO intake or significant risk factors (CD4 < 100, chemotherapy, transplant, etc.)
  • Pearl: Obtain contact information for patients PCP and specialist providers (oncology, infectious disease, rheumatology, etc). Consultation and coordination of care is especially important for patients with significant and relevant co-morbidities

External Links

[1] CDC-Microsporidiosis

References

  1. Leder K, Weller PF. Microsporidiosis. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com (Accessed on September 4, 2017.)
  2. Kotler DP, Orenstein JM. Prevalence of intestinal microsporidiosis in HIV-infected individuals referred for gastroenterological evaluation. Am J Gastroenterol 1994; 89:1998.
  3. Centers for Disease Control and Prevention. (2016). DPDx - Laboratory Identification of Parasitic Diseases of Public Health Concern - Microsporidiosis. Retrieved from https://www.cdc.gov/dpdx/microsporidiosis/index.html
  4. Pol S, Romana CA, Richard S, et al. Microsporidia infection in patients with the human immunodeficiency virus and unexplained cholangitis. N Engl J Med 1993; 328:95.
  5. Centers for Disease Control and Prevention. (2016). DPDx - Laboratory Identification of Parasitic Diseases of Public Health Concern - Microsporidiosis. Retrieved from https://www.cdc.gov/dpdx/microsporidiosis/index.html
  6. Leder K, Weller PF. Microsporidiosis. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com (Accessed on September 4, 2017.)
  7. Leder K, Weller PF. Microsporidiosis. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com (Accessed on September 4, 2017.)

Erich KDHCD Burton