Enterocytozoon bieneusi genotypes in people with gastrointestinal disorders in Queensland and Western Australia

Enterocytozoon bieneusi is the commonest pathogenic microsporidian found in humans and animals in many countries, but there is scant information on this pathogen in Australia. Here, we conducted the first molecular epidemiological investigation of E. bieneusi in humans with gastrointestinal disorders in Queensland and Western Australia. Genomic DNAs derived from 605 individual faecal samples from children (n = 279) and adults (n = 326) were extracted, and then subjected to nested PCR-based sequencing of the internal transcribed spacer (ITS) of nuclear ribosomal DNA to detect and characterise E. bieneusi. Enterocytozoon bieneusi was detected in eight of 605 human faecal samples (1.3%), including five children (≤3 years of age) and one adult (58 years) in Queensland, and two children (≤3 years) in Western Australia. Analysis of ITS sequence data revealed two known zoonotic (ALP1 and Ind4) and three novel (Hum_q1–3) genotypes of E. bieneusi. Genotype ALP1 identified here in humans has been found previously in farmed alpacas in Australia. Phylogenetic analysis showed that genotypes ALP1, Hum_q1–2 and Ind4 belonged to E. bieneusi Group 1 (with zoonotic potential), whereas genotype Hum_q3 clustered within E. bieneusi Group 10, suggesting that some genotypes within Group 10 might have zoonotic potential. Further investigations of humans, alpacas, marsupials and other animals in Australia will be significant to understand the epidemiology of E. bieneusi in Australia, to identify possible reservoirs of human infection, and to assist in the prevention and control of human microsporidiosis.