Chronic hepatitis B virus infection: a review with emphasis on therapy

Despite vaccination campaigns around the world and the resolution of the disease in immunocompetent adults, it is estimated that 400 million people worldwide are chronically infected with the hepatitis B virus (HBV). The prevalence rate of this disease in the Colombian population is low, though variable among regions: only 2% are positive in tests for the surface antigen of this virus (HBsAg). Carriers of HBV have a higher risk of developing chronic hepatitis, cirrhosis (HC), liver failure and hepatocellular carcinoma (HCC). The aims of treatment for chronic HBV infection are to completely control viral replication and to induce remission of liver damage before HC or HCC may develop. Nowadays, pharmacological therapy of HBV infection is done, among others, with pegylated interferon alfa 2a, lamivudine, adefovir, and entecavir. Patients with acute hepatitis do not need to be treated, those with acute liver failure should be evaluated for transplantation, and therapy for chronic infection should be chosen according to the degree of severity and the characteristics of their disease. Patients with acute HBV infection should be monitored every 1 to 3 months in order to detect the progression toward chronic hepatitis; for that purpose the levels of aminotransferases, bilirubin, prothrombin time, serum albumin, alpha-fetoprotein and HBV DNA are determined, and platelet count, liver biopsy, abdominal ultrasonography and upper digestive endoscopy are carried out. In patients being treated with alfa 2a pegylated interferon HBeAg, anti-HBe and HBV DNA must be measured every 6 months. These measurements should be made every 3 to 6 months in patients who use lamivudine, adefovir, entecavir or other antivirals. Other drugs with immunomodulatory or antiviral properties are being studied. The new antiviral agents include: emtricitabine, clevudine, tenofovir, telmivudine and beta L nucleosides. Immunomodulatory strategies include the use of cytokines and vaccination.