A hepatitis B subtype only seen in Aboriginal patients in northern Australia — in fact, a subtype seen in all Aboriginal patients in the NT — appears particularly dangerous, researchers say.

The subtype, called C4, was first identified in 2013, and a new cohort study has found that fibrosis and cirrhosis are highly prevalent among patients with C4.

To date, every single genotype analysis of hepatitis B (HBV) from Aboriginal Australians from the NT, as well as many from northern WA and western Queensland, has shown this genotype, says infectious diseases physician Professor Jane Davies.

“Most places where you look in the world, you will find a few different genotypes within a population,” said Professor Davies, a co-author of the new study who also helped identify C4 over a decade ago.