Includes bibliographical references (pages 9-12). Pre-publication draft : Parasitology research, Volume 88, no.10 (October 2002).

Several microsporidia species are recognized etiological agents of human diseases. Microsporidian spores have been detected by Chromotrope 2R and calcofluor stains in fecal samples of three free-ranging human-habituated mountain gorillas of Uganda and two people who share gorilla habitats, i.e., park staff members. All spore isolates have been identified by PCR with species-specific primers and fluorescent in situ hybridization (FISH) with a species-specific oligonucleotide probe to be Encephalitozoon intestinalis. Sequencing analyses of the full length SSUrRNA amplified from all spore isolates were identical with E. intestinalis SSUrRNA GenBank SIU09929. Also, sequences generated from a fragment containing the internal transcribed spacer (ITS) of these isolates were identical to GenBank sequence Y11611, i.e., E. intestinalis of anthroponotic origin. A single pathogen genotype in two genetically distant but geographically united host groups indicates anthropozoonotic transmission of E. intestinalis. It is highly unlikely that these two identical E. intestinalis genotypes were acquired independently by gorillas and people, and it is much more likely that one group initiated infection of the other. FISH assay represents a convenient cos-effective technique for rapid specific identification and viability assessment of E. intestinalis spores.