Changing Trends in the Epidemiology of Delta Virus Infection

Hepatitis delta virus (HDV) infection is an important health and economic problem worldwide. There are approximately 15 million patients with HDV worldwide and effects of 5-10% of all hepatitis B virus (HBV) infections globally. Chronic HDV infection results in 3 times more hepatocellular carcinoma (HCC) and 2 times more hepatic decompensation in cirrhosis patients compared with chronic HBV infection. HDV is associated with a higher economic burden than both HBV and hepatitis C virus (HCV) infection alone. Unlike HBV, HDV infection progresses to liver cirrhosis in 5 years, to HCC in 10 years. Risk factors for HDV infection are hepatitis B surface antigen (HBsAg) positivity, intravenous drug use, multi partner sexual behaviors, anti-human immunodeficiency virus positivity, anti-HCV positivity, men who have sex with men, healthcare workers, immigrant people moving from high HBV infection endemic areas, prisoners, hemophiliacs, poor hygienic conditions, and low economic income. From West to East, HDV prevalence increased in both patients with chronic active hepatitis (CAH) and cirrhosis. However, the prevalence of HDV infection decreased both CAH and cirrhosis after 1995 in Turkey. Amazon basin, Indian population living in Venezuela, and the Santa Marta region of Colombia are areas of the highest HDV prevalence. Due to immigration from high HBV infection endemic areas to industrialized countries, Delta infection continues stably 5-10 % in HBsAg carriers. Each HBsAg-positive patient should be checked for anti-delta antibody to prevent rapid progress of parenchymal liver diseases.