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Review
. 2006 Oct;19(5):485-92.
doi: 10.1097/01.qco.0000244055.46382.23.

Microsporidiosis: current status

Elizabeth S Didier  1 , Louis M Weiss
Affiliations
Review

Microsporidiosis: current status

Elizabeth S Didier et al. Curr Opin Infect Dis. 2006 Oct.

Abstract

Purpose of review: Microsporidiosis is an emerging and opportunistic infection associated with a wide range of clinical syndromes in humans. This review highlights the research on microsporidiosis in humans during the previous 2 years.

Recent findings: The reduced and compact microsporidian genome has generated much interest for better understanding the evolution of these parasites, and comparative molecular phylogenetic studies continue to support a relationship between the microsporidia and fungi. Through increased awareness and improved diagnostics, microsporidiosis has been identified in a broader range of human populations that, in addition to persons with HIV infection, includes travelers, children, organ transplant recipients, and the elderly.

Summary: Effective commercial therapies for Enterocytozoon bieneusi, the most common microsporidian species identified in humans, are still lacking, making the need to develop tissue culture and small animal models increasingly urgent. Environmental transport modeling and disinfection strategies are being addressed for improving water safety. Questions still exist about whether microsporidia infections remain persistent in asymptomatic immune-competent individuals, reactivate during conditions of immune compromise, or may be transmitted to others at risk, such as during pregnancy or through organ donation. Reliable serological diagnostic methods are needed to supplement polymerase chain reaction or histochemistry when spore shedding may be sporadic.

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Figures

Figure 1
Figure 1. Life cycle of the four most prevalent species of microsporidia that infect humans
Most infections are believed to occur through ingestion or inhalation of spores that are the mature stages of the microsporidia. Encephalitozoon species are shown to typically cause disseminated infections. Enterocytozoon bieneusi primarily infects the gastrointestinal tract, but recent reports suggest that extraintestinal infections may also occur. Organisms are typically shed with feces, urine, or respiratory secretions to transmit infections. This figure was reprinted with permission from the DPDx: CDC's website for parasite identification; http://www.dpd.cdc.gov/dpdx/.
See this image and copyright information in PMC

References

    1. Desportes I, Le Charpentier Y, Galian A, et al. Occurrence of a new microsporidian: Enterocytozoon bieneusi n.g., n. sp., in the enterocytes of a human patient with AIDS. J Protozool. 1985;32:250–254. - PubMed
    1. Katinka MD, Duprat S, Cornillot E, et al. Genome sequence and gene compaction of the eukaryote parasite Encephalitozoon cuniculi. Nature. 2001;414:450–453. - PubMed
    1. Didier ES. Microsporidiosis: an emerging and opportunistic infection in humans and animals. Acta Trop. 2005;94:61–76. - PubMed

    2. The names of the microsporidia are continuously changing as new information is obtained. This review includes a table listing the currently recognized species of microsporidia that infect humans and cites references for the first descriptions, original taxonomic descriptions, current designations, and other known hosts and environmental sources. It should be noted, however, that the Brachiola species presented in this citation were recently transferred to Anncaliia (see Ref. [32•]).

    1. Franzen C, Muller A. Cryptosporidia and microsporidia: waterborne diseases in the immunocompromised host. Diagn Microbiol Infect Dis. 1999;34:245–262. - PubMed
    1. Vavra J, Larsson R. Structure of the microsporidia. In: Wittner M, Weiss LM, editors. The microsporidia and microsporidiosis. Washington, DC: American Society for Microbiology; 1999. pp. 7–84.

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