Prevalence of intestinal encephalitozoonosis in Mexico.

Infections with Encephalitozoon (phylum Microspora) protozoa in immunodeficient patients have emerged worldwide. The prevalence of infections due to Encephalitozoon species in nonclinical populations remains unclear. We conducted a cross-sectional survey of two rural highland villages in Mexico by using monoclonal antibody 3B6 to Encephalitozoon in immunofluorescence to assess the prevalence of Encephalitozoon spores in human stools. We found that 20 (7.84%) of the 255 subjects were positive and that 15 (21.4%) of the 70 households had at least one member who was positive. These results suggest that Encephalitozoon species, most likely Encephalitozoon intestinalis, may be commonly present in community settings.

Simple diagnosis of Encephalitozoon sp. microsporidial infections by using a panspecific antiexospore monoclonal antibody.

Microsporidia (phylum Microsproa) have recently become recognized as common opportunistic protozoans in the United States and worldwide, particularly affecting immunodeficient patients. Microsporidian organisms within the genus Encephalitozoon are the cause of nephrologic, ophthalmic, pneumologic, gastroenteric, and systemic infections. However, diagnosis of the small spores by light microscopy is difficult, even with newly developed and improved staining techniques. We have developed an anti-Encephalitozoon species monoclonal antibody-based immunoassay for easy diagnosis. A hybridoma was produced and selected following one main criterion: recognition by immunofluorescence of all known Encephalitozoon spores affecting humans. The selected monoclonal antibody-secreting hybridomas were characterized by enzyme-linked immunosorbent assay, immunofluorescence, Western blot, and immunoelectron microscopy using Encephalitozoon species from fresh and fixed samples from patients and from in vitro cultures. In the immunofluorescence assay, one monoclonal antibody, termed 3B6, strongly recognized Encephalitozoon cuniculi, E. hellem, and E. intestinalis. Monoclonal antibody 3B6 bound to other microsporidia (Nosema and Vairimorpha spp.) without cross-reacting with any other parasite, including Enterocytozoon bieneusi, fungus, or bacterium tested. In immunoelectron microscopy assays, monoclonal antibody 3B6 bound to the exospore of Encephalitozoon species, while in Western blot assays, it recognized three to seven antigens with molecular masses ranging from 34 to 117 kDa. We have developed a sensitive and specific monoclonal antibody-based immunoassay to diagnose common microsporidian infections, particularly with Encephalitozoon species. This is a new tool for identifying spores in bodily fluids and biopsy samples and is an efficient diagnostic test. Additionally, monoclonal antibody 3B6 can serve to assess the prevalence of microsporidial infections in immunodeficient and immunocompetent patients.