Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android

Key Features

Essentials of Diagnosis

  • Acute diarrhea, especially in children in developing countries

  • Outbreaks of diarrhea secondary to contaminated water or food

  • Prolonged diarrhea in immunocompromised persons

  • Diagnosis mostly by identifying organisms in specially stained stool specimens

General Considerations

  • Infection occurs mainly by ingestion of spores, but also by direct inoculation of the eyes

  • May be transmitted from person to person or by contaminated drinking or swimming water or food

  • Cysts can remain viable in the environment for years


  • Occurs worldwide, particularly in the tropics and in regions where hygiene is poor

  • Clustering occurs in households, day care centers, and among sexual partners

Clinical Findings

Symptoms and Signs

In immunocompetent patients

  • Most commonly presents as self-limited diarrhea

  • Ocular infections have also been described

In immunocompromised patients

  • Most commonly caused by Enterocytozoon bieneusi and Encephalitozoon intestinalis

  • Chronic diarrhea, with anorexia, bloating, weight loss, and wasting

  • Fever is usually not seen

  • Other illnesses include

    • Biliary tract disease (AIDS cholangiopathy)

    • Genitourinary infection with cystitis

    • Kidney disease

    • Hepatitis

    • Peritonitis

    • Myositis

    • Respiratory infections including sinusitis

    • Central nervous system infections including granulomatous encephalitis

    • Disseminated infections

  • Ocular infections with Encephalitozoon species cause conjunctivitis and keratitis, presenting as redness, photophobia, and loss of visual acuity


Laboratory Findings

  • Identification of organisms in stool, fluid, or tissue specimens using Weber chromotrope-based stain

Diagnostic Studies

  • Electron microscopy is helpful for confirmation of the diagnosis and speciation

  • Polymerase chain reaction and culture techniques are available but not used routinely


  • Albendazole (400 mg orally twice daily for 2–4 weeks)

    • Has activity against a number of species, but relatively poor efficacy (about 50%) against E bieneusi, the most common microsporidial cause of diarrhea in patients with AIDS

    • Used to treat gastrointestinal and other manifestations

  • Fumagillin

    • Has shown benefit in clinical trials at a dose of 20 mg orally three times per day for 14 days

    • Treatment was accompanied by reversible thrombocytopenia

  • For ocular microsporidiosis

    • Fumagillin solution (3 mg/mL)

    • Consider concurrent systemic therapy with albendazole

    • Adjunctive management may include corticosteroids to decrease inflammation and keratoplasty

  • Antiretroviral therapy is the best means of controlling microsporidiosis in patients with AIDS



  • Optimal means of preventing microsporidial infections are not well understood, but water purification as discussed above and body substance precautions for immunocompromised and hospitalized individuals are likely effective


Almeria ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.