Enterocytozoon bieneusi Genotypes in Cattle on Farms Located within a Water Catchment Area.

Enterocytozoon bieneusi is a microsporidian found in humans and other animals around the world. Investigations in some countries, such as the U.S., have indicated the importance of E. bieneusi as a zoonotic water- and food-borne pathogen. However, there is scant epidemiological information on E. bieneusi in animals in many countries including Australia. Here, we conducted the first molecular epidemiological study of E. bieneusi in farmed cattle in Victoria, Australia, to assess whether these bovids are carriers of "zoonotic" genotypes of E. bieneusi. A total of 471 individual faecal samples were collected from calves of < 3 mo and of 3-9 mo of age. Genomic DNAs were extracted from individual faecal samples and then subjected to nested PCR-based sequencing of the internal transcribed spacer (ITS) of nuclear ribosomal DNA to identify E. bieneusi and define genotypes. Enterocytozoon bieneusi was detected in 49 of the 471 samples (10.4%). An analysis of ITS sequence data revealed three known genotypes (BEB4, I, and J) and three novel genotypes (designated TAR_fc1 to TAR_fc3). Phylogenetic analysis showed that genotypes BEB4, I, J, TAR_fc1, and TAR_fc2 clustered with genotypes identified previously in humans, indicating that cattle are carriers of E. bieneusi with zoonotic potential.