In a study published in the Journal of Hepatology, Professor Anna Maria Geretti and Dr Alexander Stockdale from the University of Liverpool (United Kingdom), in collaboration with researchers from WHO and the International Agency for Research on Cancer (IARC), estimate that worldwide, hepatitis D virus (HDV) affects nearly 5% of people who have a chronic infection with hepatitis B virus (HBV), and that HDV co-infection could explain about 1 in 5 cases of liver disease and liver cancer in people with HBV infection.