Australian researchers have discovered a hepatitis B virus (HBV) subtype that is 53,000 years old, suggesting that the liver disease may have co-evolved with humans since ancient people first left Africa, reports.

The new HBV strain is called C4 and has not been found outside of Australia’s Northern Territory, whose indigenous residents have high rates of liver cancer.

Researchers found the virus while undertaking “genetic fingerprinting” research among HBV-positive indigenous people in the territory. Besides its impressive age, the viral subtype also seems to be far more aggressive than other hep B strains.

In Northern Australia, it is estimated that between 5 and 10 percent of adults are living with hep B. Researchers found the highly volatile ancient subtype in nearly every person they tested.

Their report, published by Australia’s CHARM project, stressed the importance of diagnosing HBV early to prevent liver cancer in indigenous populations.