Hepatitis B virus

What is Hepatitis B?

Hepatitis B is an infection by a virus mostly replicating in the liver, called the hepatitis B virus (HBV). This virus can be easily transmitted to others. When acquired during delivery of infancy, hepatitis B infection usually become a chronic infection. Worldwide, 296 million people are chronically infected with HBV, most of them in Asia and sub-Saharan Africa. Chronic infection causes the death of liver cells (hepatocytes), inflammation and fibrosis, which may lead to liver cirrhosis and/or liver cancer (hepatocarcinoma). ​

In newborns and infants, acute infection after contamination is usually not recognized as there are no symptoms for several decades. In adults who are not immunized, acute hepatitis B can be symptomatic (fever, jaundice, fatigue) and, exceptionally, causes death. In about 5% of cases, the infection becomes chronic.


Transmission ​

HBV may survive around 7 days out of the body and could remain contagious during this time.

The hepatitis B virus is easily transmitted to a non-immunized person via contact of infected blood, semen or other body fluids with mucosa, wound or skin tears.

It seems most commonly transmitted in the following circumstances:

  • During delivery from an infected mother to her infant
  • During infancy, in the absence of immunization, from an infected person close to the infant
  • During sex activities with an infected partner
  • Using needles, syringes, or any injection equipment contaminated with infected blood
  • Using instruments such as razors that have been used by an infected person
  • Exposure to infected body fluids through needle sticks, or any wound by an equipment contaminated with infected blood

Hepatitis B is not spread through sneezing, coughing, hugging, or breastfeeding. it is not believed to be spread through kissing or sharing kitchen utensils.


It is usually not known that another person is living with HBV. Therefore, immunization is the best way to be protected for life.

A vaccine against hepatitis B is available since the early 1980’s. It is safe, cheap and effective in preventing infection. ​

WHO recommends “universal immunization”: for all infants, first dose at birth, followed by two doses within the first 6 months of life. Immunization of older children and adults consists of three doses at appropriate intervals (about one month).


Chronic hepatitis B infection can be treated with oral antiretroviral agents. Treatment can prevent the consequences of the liver infection, such as progression to cirrhosis and liver cancer but usually cannot definitely stop viral replication. Thus, the treatment cannot be interrupted because viral replication would resume.

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