Chronic hepatitis B and liver damage

In some people, the hepatitis B virus continues to reproduce in the body long after initial infection. They are sometimes called 'chronic carriers', meaning that they are infectious for life, although they may not experience any symptoms themselves. Approximately 90% of babies exposed to the hepatitis B virus before the age of one year become chronic carriers, compared to 20 to 50% of children aged one to five years at the time of exposure. In contrast, only 5 to 10% of HBV-infected adults go on to develop chronic infection, even though about half develop symptoms of acute infection. People co-infected with HIV are less likely to clear the hepatitis B virus without treatment.

Several factors affect progression to chronic liver inflammation, cirrhosis and liver cancer. These include the state of the immune system, gender, hepatitis C or HIV co-infection, the age of the patient at time of infection, the stage of infection and other genetic and viral factors. Hepatitis B viral genotype C has been associated with greater risk of liver inflammation, cirrhosis and liver cancer than genotype B.1 2 3 4

Given the many factors that affect hepatitis B progression, estimates of progression rates tend to vary. Approximately 15 to 25% of people with untreated chronic hepatitis B will go on to develop cirrhosis or liver cancer, although this may be lower in women.5

HIV-positive people who contract hepatitis B are at higher risk of becoming chronic carriers of the virus and of developing advanced liver damage, as are people who receive immunosuppressive treatments following a transplant.6

The liver damage experienced by some people with hepatitis B is caused not by the virus itself, but by the immune system's destruction of infected cells in the liver. Because the immune responses of people with HIV are often impaired, HIV-positive people with chronic hepatitis B virus infection may be less likely to experience liver damage than people with fully functioning immune systems.7 Conversely, HIV-positive people may have higher levels of hepatitis B virus in their blood due to their weakened immune systems, so HIV-positive carriers of the hepatitis B virus may be more infectious than their HIV-negative counterparts.

A review of people with hepatitis B in the EuroSida cohort found that only 34% had undectable hepatitis C viremia, despite the fact that 90% of patients were receiving antiretroviral treatment. Twenty per cent of all patients had a viral load above 10 million copies, indicating a significantly higher risk of progression to liver disease in this subset.8

Hepatitis B genotype G, which is rare in Europe and North America, has been associated with a higher risk of fibrosis.9

References

  1. Chu C et al. Genotype C hepatitis B virus infection is associated with a higher risk of reactivation of hepatitis B and progression to cirrhosis than genotype B: a longitudinal study of hepatitis B e antigen-positive patients with normal aminotransferase levels at baseline. J Hepatol 43: 411-417, 2005
  2. Chan HL et al. Viral genotype and hepatitis B virus DNA levels are correlated with histological liver damage in HBeAg-negative chronic hepatitis B virus infection. Am J Gastroenterol 97: 406-412, 2002
  3. Tsubota A et al. Genotype may correlate with liver carcinogenesis and tumor characteristics in cirrhotic patients infected with hepatitis B subtype adw. J Med Virol 65: 257-265, 2001
  4. Kao JH et al. Genotypes and clinical phenotypes of hepatitis B virus in patients with chronic hepatitis B virus infection. J Clin Microbiol 40: 1207-1209, 2002
  5. Dickinson JA et al. Modelling death rates for carriers of hepatitis B. Epidemiol Infect 128: 83-92, 2001
  6. Sinicco A et al. Coinfection and superinfection of hepatitis B virus in patients infected with human immunodeficiency virus: no evidence of faster progression to AIDS. Scan J Infect Dis 29: 111-115, 1997
  7. Perrillo RP et al. Chronic hepatitis B in asymptomatic homosexual men with antibody to the human immunodeficiency virus. Ann Intern Med 105: 382-383, 1986
  8. Vogel M et al. Epidemiological and virological characteristics of chronic HBV infection in HIV-positive patients in Europe, Twelfth European AIDS Conference, Cologne, abstract PS2/2, 2009
  9. Lacombe K et al. Major role of hepatitis B genotypes in liver fibrosis during coinfection with HIV. AIDS 20: 419-427, 2006
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