How Common is Hepatitis B Infection and How it is Transmitted?

Hepatitis B infection is infectious disease of liver caused by hepatitis B virus (HBV). Hepatitis B was known previously as serum hepatitis. It is endemic in parts of Asia (including China) and Africa. According WHO estimate every year more than half a million people die due to hepatitis B virus infection.

How common is hepatitis B infection?

It is estimated that approximately one third of world population has been infected at some point of their life. Out of these approximately 350 million have become chronic carriers and act as reservoir of infection of hepatitis B. The prevalence rate of hepatitis B infection varies from country to country and in the same country it varies from region to region. The prevalence rate is as high as 10% or more in some parts of Asia and low of approximately 0.5% in United States and Europe.

How hepatitis B infection is transmitted?

The main mode of transmission is by exchange of body fluid (i.e. semen, blood etc.). The modes of transmission of hepatitis B infection are:

  • Exposure to infectious body fluids containing the virus (hepatitis B virus) such as blood or blood products transfusion.
  • Sexual contact (if semen contain virus).
  • Through use of contaminated needles, this generally occurs due to reuse or inappropriate sterilization of needles and syringes, as seen among intravenous drug addicts.
  • Vertical transmission, i.e. transmission from mother to child during childbirth. If mother in positive for HBsAg (hepatitis B surface antigen) the risk of transmission of hepatitis B infection from mother to child during delivery is 20% if no preventive intervention is applied. The risk increases to approximately 90%, if the mother is positive for HBeAg (hepatitis B e antigen) also. This is an important mode of transmission of hepatitis B in Africa and Asian high endemic regions such as China.
  • Between family members, this may be due to contact of non-intact skin or mucous membrane with secretions containing hepatitis B virus. Objects (fomites), such as toys may contain hepatitis B virus which may live up to one week and transmit the disease.

But up to 30% of adults with hepatitis B virus infection, the mode of transmission can not be established.

Image: Victor Habbick /

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