BACKGROUND: The incidence and trends in hepatitis D virus (HDV) in Australia have not been recently assessed and the circulating genotypes have never been determined.AIM: This study aimed to characterise the current virology and epidemiology of HDV.METHODS: Notifiable disease surveillance and laboratory testing data were analysed to assess demographics, risk factors, and trends. HDV serology and RNA testing were performed on requested samples from 2010-2016. Sequencing of a 500 nucleotides amplicon of the delta antigen and phylogenetic analysis of the strains from 2009-2016 was also conducted.RESULTS: Ninety HDV notifications were reported to the Victorian Department of Health and Human Services between 2010-2016. The majority (64.4%) of those diagnosed were born overseas, most commonly in Sudan, Pakistan and Vietnam. Over the same period 190 patients tested positive for anti-HDV serology and 166 for HDV RNA. Sequencing of isolates from 169 individuals between 2009 and 2016 revealed 80.5% strains were genotype 1, 16% genotype 5 and 3.5% genotype 2. Phylogenetic analysis confirmed relatedness of strains from birth country; revealed the presence of the "Pacific Island" genotype 1 strain in Queensland; and supported possible transmission in correctional facilities and within families.CONCLUSIONS: This study demonstrates the ongoing need for routine HDV screening and engagement in clinical care for people living with HBV in Australia. epidemiologic findings highlight the diversity in those affected and provides insights into the local and global geographic distribution and transmission patterns. This article is protected by copyright. All rights reserved.