Microsporidiosis: epidemiology, clinical data and therapy.

Microsporidiosis is an emerging and opportunistic infection in AIDS patients, organ transplant recipients, children, travelers, contact lens wearers and the elderly. It is associated with a wide range of clinical syndromes of microsporidiosis in humans. The disease is caused by microsporidia, obligate intracellular microorganisms that were recently reclassified from protozoa to fungi. 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 of water-borne, food-borne and zoonotic transmission. Various molecules have been tested for treating microsporidiosis in humans with variable success. Albendazole is effective against Encephalitozoon species such us Encephalitozoon intestinalis but not against Enterocytozoon bieneusi. This species has shown excellent clinical therapeutic response to direct action with fumagillin, but this drug is toxic when administered systematically to mammals. Its analog, TNP 470, could be promising alternative. Further work is necessary to identify other drugs, which are both effective and devoid of adverse effects.