Disease / Pathology

The Microsporidia are a very large group of organisms that have been traditionally difficult to place within other groups of organisms because they are unicellular with some characteristics of more complex organisms yet falling in as a fungi in other characteristics. It is generally treated as a parasite in most text books/literature while identified as a fungus.

They generally produce spores that are highly resistant with a size range of between 1-4 um for most clinically important species. There are literally over a thousand species of Microsporidia yet only a small fraction that are known to cause human disease. To be more specific there have been to date about 15 species known to cause disease in humans.

When it does cause disease in humans it most commonly afflicts the immunocompromised such as those undergoing immunosuppressive therapy or HIV/AiDS patients. The location of the infection invariably depends on the species causing the infection as various species have more of a predilection for certain organ/body sites. The table below is a short list of some species and their predominant site of localization in the human host.

Location in the Host

Microsporidia species location in infections varies with the species and the host. See table above.

Geographic Distribution

Microsporidia species with a worldwide distribution though various species are found more commonly in certain areas of the world then other areas.

Life Cycle

Morphology & Diagnosis

Microsporidia species identification is dependent on the clinical symptoms in an immunocompromised person, site of infection, and staining of suspected biopsy material collected.

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