First detection and genetic characterisation of Enterocytozoon bieneusi in wild deer in Melbourne’s water catchments in Australia

Enterocytozoon bieneusi is reported to be a common microsporidian of humans and animals in various countries. However, E. bieneusi has yet to be recorded in animals in Australia. Here, we undertook the first molecular epidemiological investigation of E. bieneusi in three species of deer (Cervus elaphus, Dama dama and Rusa unicolor) that live in the catchment areas that supply the city of Melbourne with drinking water. Genomic DNA was extracted from a total of 610 individual faecal samples from wild deer, including sambar deer (Rusa unicolor) (n = 516), red deer (Cervus elaphus) (n = 77) and fallow deer (Dama dama) (n = 17) from nine catchment areas, and then tested using a nested PCR-based sequencing approach employing internal transcribed spacer (ITS) of nuclear ribosomal DNA as the genetic marker. Enterocytozoon bieneusi was detected in 25 of all 610 (4.1%) samples exclusively in samples from sambar deer. The analysis of ITS sequence data revealed three known (D, J and Type IV) and two new (MWC_d1 and MWC_d2) genotypes of E. bieneusi. Although the significance of the latter two new genotypes is presently unknown, phylogenetic analysis of ITS sequence data sets showed that they cluster with genotypes D and Type IV, which have been recorded previously in humans. These findings suggest that sambar deer in the water catchments harbour zoonotic genotypes of E. bieneusi. Further insight into the epidemiology of E. bieneusi in wildlife, water and the environment in Australia will be important to have an informed position on the public health significance of microsporidiosis caused by this microbe.