Chronic hepatitis B
Chronic Hepatitis B is a potentially life-threatening liver infection caused by the HBV. Worldwide, an estimated two billion people were HBV infected, whereas more than 350 million of those have chronic liver infections. Chronic hepatitis B is a serious global public health issue. Up to 1.2 million deaths per year are caused by HBV-related chronic liver diseases resulting in it being the 10th leading cause of death worldwide. Without appropriate treatment, 15-25% of the chronically infected will die prematurely because of the severe and fatal complications of chronic liver disease. The ideal endpoint of the therapy is sustained Hepatitis B virus s antigen (HBsAg) loss with or without seroconversion to anti-HBs. This is associated with a complete and definitive remission of the activity of CHB and an improved long-term outcome. However, this goal can be achieved only in minority of patients with available therapies.
Chronic hepatitis delta
Hepatitis delta is the most severe form of viral hepatitis. It is caused by HDV, a small RNA virus, which requires helper functions from HBV for virion assembly and propagation, and uses the HBV envelope for virus release and infection of new cells. About 5% of chronically HBV infected are co-infected with HDV. Immunization against HBV also protects against HDV infection. The presence of HDV is associated with more severe and rapid progression of liver disease than HBV infection alone. Liver cirrhosis and decompensation occur earlier and more frequently in course of HBV/HDV co-infection than in HBV mono-infection. The therapeutic options for HDV co-infected patients are very limited. Only interferons show some degree of efficacy in a small proportion of patients with approximately 25% of virological and biochemical response. However, high proportion of responders relapse several years after the cessation of treatment. Antiviral agents active against HBV do not work against HDV.