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Hepatitis – Causes

Causes

HBV, HCV and HIV share transmission routes, and exhibit biological similarities. HBV and HCV infections are major causes of chronic liver disease and related deaths worldwide.1–3

  • HBV, HCV and HIV  produce large numbers of virions and have high mutation rates,3 but while HCV can be completely eradicated from the body,4 HIV and HBV currently cannot.3

Hepatitis B

  • ‘Wild-type’ HBV is the primary cause of hepatitis B e antigen (HBeAg)-positive disease, which typically represents the early phase of chronic HBV infection, although patients can have HBeAg-positive disease for several years2
  • Naturally occurring HBV variants with genomic nucleotide substitutions are primarily the cause of HBeAg-negative disease and this represents a later phase of chronic HBV infection2
    • a HBeAg-negative, inactive HBV carrier state may follow seroconversion from HBeAg to anti-HBe antibodies. This state is characterized by very low or undetectable serum HBV DNA levels and normal aminotransferases.2
  • Eight HBV genotypes (A–H) have been identified
    • HBV genotype may influence response to interferon therapy and progression of HBV-related liver disease5
    • additional data on the relation between HBV genotypes and treatment response are needed before testing for HBV genotypes in clinical practice is recommended5
  • HBV is transmitted by the percutaneous route or by sexual, peri-natal and close person-to-person contact via open cuts and sores (particularly among children in endemic areas)5

Hepatitis C

  • Similarly to HBV, HCV typically exists within the body as a quasispecies, ie as populations of viral variants3
  • There are six HCV genotypes (1–6), and many subtypes (a, b, etc). The chances of successful treatment vary with HCV genotype1
  • Historically, the principal routes of HCV transmission were infected blood transfusion, unsafe injection procedures and intravenous drug use. New HCV infections are generally linked to intravenous or nasal drug use rather than unsafe medical or surgical procedures, and recent data have linked promiscuous male homosexual activity to increased risk of HCV infection1
  • In contrast to HBV transmission, there is a low risk of HCV transmission through peri-natal contact or heterosexual intercourse1
    • occasionally, parenteral transmission via resulting from unsafe tattooing or acupuncture techniques has been implicated in HCV transmission1

References

  1. European Association for the Study of the Liver (EASL). Clinical practice guidelines: management of hepatitis C virus infection. J Hepatol 2011;55:245–264. Accessed 1 December 2011.
  2. European Association for the Study of the Liver (EASL). Clinical Practice Guidelines: Management of Chronic Hepatitis B. J Hepatol 2009;50:227–242. Accessed 1 December 2011.
  3. Soriano V, Perelson AS, Zoulim F. Why are there different dynamics in the selection of drug resistance in HIV and hepatitis B and C viruses?  J Antimicrob Chemother 2008;62:1–4.
  4. European AIDS Clinical Society (EACS). Guidelines Version 6.0. Accessed 30 November 2011.
  5. American Association for the Study of Liver Diseases (AASLD). Practice Guideline. Chronic Hepatitis B: Update 2009. Accessed 1 December 2011.