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Medical Author:

Steven Doerr, MD

Steven Doerr, MD

Steven Doerr, MD, is a U.S. board-certified Emergency Medicine Physician. Dr. Doerr received his undergraduate degree in Spanish from the University of Colorado at Boulder. He graduated with his Medical Degree from the University Of Colorado Health Sciences Center in Denver, Colorado in 1998 and completed his residency training in Emergency Medicine from Denver Health Medical Center in Denver, Colorado in 2002, where he also served as Chief Resident.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• What is microsporidiosis? What causes the disease?
• How are microsporidia transmitted?
• What symptoms does microsporidiosis cause?
• How is microsporidiosis diagnosed?
• How is microsporidiosis treated?
• How is microsporidiosis prevented?
• Microsporidiosis At A Glance
• Microsporidiosis Index

Microsporidia spores are released from the stool and urine of infected animals. A number of animals, including insects, birds, and mammals, can serve as reservoirs of infection for microsporidia. These spores are then consumed or inhaled by humans.

Once within a cell, the microsporidia develop and multiply, producing more spores. The infective spores are then released when the cell expands and bursts.

Although microsporidiosis can occur in people with normal immune systems, it is very uncommon. The symptoms of microsporidiosis primarily occur in people with immune-system deficiency, such as HIV-infected individuals and organ-transplant recipients. Microsporidiosis can cause intestinal, lung, kidney, brain, sinus, muscle, or eye disease.

Intestinal symptoms that are caused by microsporidia infection include chronic diarrhea, wasting, malabsorption, and gallbladder disease. In patients with AIDS, the chronic diarrhea may be extremely debilitating and carries a significant mortality risk. The majority of cases of intestinal microsporidiosis in AIDS patients are caused by Enterocytozoon bieneusi.

Lung symptoms may include a cough and difficult, labored breathing. A chest X-ray may show signs of inflammation, fluid, or cavities in the lungs.

Microsporidiosis can cause infection in the urinary tract, kidney failure, bladder inflammation, and bowel perforation. Microsporidia can also spread throughout the body to cause inflammation in the brain, pancreas, sinuses, and muscle tissue.

Eye infection with microsporidia can cause inflammation of the cornea and conjunctiva (keratoconjunctivitis). Symptoms of ocular microsporidiosis may include eye pain, eye redness, or blurry vision.