Microsporidia infection is caused by parasitic obligate intracellular spore-producing fungi or closely similar organisms. Previously, microsporidia were categorized as protozoa. Of the more than 1,400 species of microsporidia, at least 15 are linked to disease in humans. Inhalation, ingestion, interaction with animals, direct contact with the conjunctiva, and person-to-person transmission are all ways that the spores of the organism might be acquired.

Only a few cases of human infection were documented before the AIDS epidemic, possibly because there was less general knowledge of microsporidia infection. Microsporidia are likely a prevalent source of subclinical or moderate self-limited sickness in otherwise healthy individuals. Microsporidial keratoconjunctivitis in immunocompetent persons has been documented more frequently lately.


The microsporidia-related clinical disease varies with

  • The type of parasite
  • The host’s level of immunity

Microsporidia can induce an asymptomatic infection in immunocompetent persons or self-limited watery diarrhea. Keratoconjunctivitis caused by eye infections has been reported.

Chronic diarrhea, wasting, malabsorption, punctate keratoconjunctivitis, cholangitis, hepatitis, peritonitis, myositis, and sinusitis are all symptoms of several microsporidia species that affect people with AIDS. Gallbladder and kidney infections have both happened. Numerous species of Vittaforma corneum, including punctate keratopathy with redness and irritation and severe stromal keratitis that can impair vision, can cause ocular infections.


  • Microscopy using light or electrons and specific stains
  • Occasionally, assays based on immunofluorescence or polymerase chain reaction (PCR)

It is possible to identify the infecting organisms in biopsy samples of the affected tissue as well as in stool, cerebrospinal fluid, urine, sputum, and corneal scrapings. The best way to see microsporidia is with certain staining procedures. Spores can be seen in tissues and smears using fluorescent brighteners. The quickest method is quick-hot Gramme chromotrope.

Specialized laboratories offer PCR-based testing and immunofluorescence assays (IFA). The most sensitive test available right now is transmission electron microscopy; however, it cannot be used for regular diagnosis.

For speciation, scientists use molecular techniques.


Initiating or improving ART for people with AIDS is crucial. The degree of immune reconstitution with ART determines the duration of antimicrobial therapy and the outcome. The infectious microsporidia species, the immunological health of the human host, and the affected organs all affect how antibiotic treatment for microsporidiosis is administered. Information on available treatments is limited.

Albendazole, a broad-spectrum anthelmintic of the benzimidazole type intended to treat infections caused by certain microsporidia, can have substantial side effects, including liver damage in 10% of patients and, infrequently, low white blood cell counts.

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