Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/26/2003
Publication Date: 8/1/2003
Citation: SULAIMAN, I.M., FAYER, R., LAL, A.A., TROUT, J.M., SCHAEFER, F., XIAO, L. MOLECULAR CHARACTERIZATION OF MICROSPORIDIA INDICATES THAT FUR-BEARING MAMMALS CAN BE A SOURCE OF HUMAN PATHOGENIC ENTEROCYTOZOON BIENEUSI. EMERGING INFECTIOUS DISEASES. 2003. Vol.69. pp. 4495-4501. Interpretive Summary: Microsporidia are obligate, intracellular, protozoan parasites with 14 species reported to infect humans. Enterocytozoon bieneusi, the most common microsporidian that infects humans, also infects cattle, but little is known of reservoirs or routes of infection. The possibilities that E. bieneusi might result in zoonotic infection under certain circumstances and that spores might be spread by water led to the present study in which beaver, muskrats, otters, foxes, and raccoons closely associated with grazing cattle and with surface waters, were trapped and their feces examined for the presence of spores. This study, the first involving wildlife in the epidemiology of these parasites, found extensive genetic diversity in E. bieneusi, some genotypes being potentially zoonotic. The data should be useful in the development of alternative molecular tools for the detection and differentiation of E. bieneusi parasites, and in the investigations of outbreaks or endemic diseases.
Technical Abstract: Over 13 months, 558 beavers, foxes, muskrat, otters, and raccoons were trapped in 4 counties in eastern Maryland. Feces from all animals were stained with Calcofluor white and examined by fluorescence microscopy and 465 specimens were examined by molecular methods for microsporidia. Samples from the internal transcribed spacer (ITS) region of the rRNA gene of Enterocytozoon bieneusi were characterized. A two-step nested PCR protocol was developed to amplify a 392 bp fragment of the ITS region from the E. bieneusi isolates, using primers complementary to the conserved regions of published E. bieneusi nucleotide sequences. Fifty-nine samples were sequenced and multiple alignments of these sequences identified 15 genotypes of E. bieneusi, of these 13 E. bieneusi genotypes have not been reported before. Most of the E. bieneusi genotypes were found in multiple species of wildlife. Some of the isolates of muskrats and raccoons formed two distinct groups; others belong to a major group consisting of all the previously described E. bieneusi genotypes from human and non-human sources. Results of this study indicate that fur-bearing mammals, especially those closely associated with surface water can be a potential source of human-pathogenic E. bieneusi.