Microsporidiosis: An emerging and opportunistic infection in humans and animals

• Published in: Acta tropica Vol. 94; no. 1; pp. 61 - 76
• Main Author: Didier, Elizabeth S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2005
• Subjects: Animals; Anti-Bacterial Agents - therapeutic use; Aspergillus fumigatus; Cyclohexanes; Emerging infection; Encephalitozoon; Encephalitozoon intestinalis; Enterocytozoon; Enterocytozoon bieneusi; Fatty Acids, Unsaturated - therapeutic use; Humans; Microsporidia; Microsporidia - growth & development; Microsporidia - immunology; Microsporidia - metabolism; Microsporidiosis - diagnosis; Microsporidiosis - drug therapy; Microsporidiosis - epidemiology; Microsporidiosis - immunology; Opportunistic infection; Opportunistic Infections - drug therapy; Opportunistic Infections - epidemiology; Opportunistic Infections - immunology; Opportunistic Infections - microbiology; Polyamines - therapeutic use; Sesquiterpenes; Vittaforma corneae; Zoonoses - epidemiology; Zoonoses - microbiology; Zoonosis; Opportunistic infection; Encephalitozoon; Emerging infection; Zoonosis; Enterocytozoon
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2005.01.010

Microsporidia have emerged as causes of infectious diseases in AIDS patients, organ transplant recipients, children, travelers, contact lens wearers, and the elderly. These organisms are small single-celled, obligate intracellular parasites that were considered to be early eukaryotic protozoa but were recently reclassified with the fungi. Of the 14 species of microsporidia currently known to infect humans, Enterocytozoon bieneusi and Encephalitozoon intestinalis are the most common causes of human infections and are associated with diarrhea and systemic disease. Species of microsporidia infecting humans have been identified in water sources as well as in wild, domestic, and food-producing farm animals, raising concerns for waterborne, foodborne, and zoonotic transmission. Current therapies for microsporidiosis include albendazole which is a benzimidazole that inhibits microtubule assembly and is effective against several microsporidia, including the Encephalitozoon species, but is less effective against E. bieneusi. Fumagillin, an antibiotic and anti-angiogenic compound produced by Aspergillus fumigatus, is more broadly effective against Encephalitozoon spp. and Enterocytozoon bieneusi but is toxic when administered systemically to mammals. Gene target studies have focused on methionine aminopeptidase 2 (MetAP2) for characterizing the mechanism of action and for identifying more effective, less toxic fumagillin-related drugs. Polyamine analogues have shown promise in demonstrating anti-microsporidial activity in culture and in animal models, and a gene encoding topoisomerase IV was identified in Vittaforma corneae, raising prospects for studies on fluoroquinolone efficacy against microsporidia.