Hepatitis B virus (HBV) is a highly infectious virus that can cause either an acute hepatitis or chronic infection. It primarily affects liver, but can be found elsewhere in the body. There is a wide spectrum of disease in chronic infection, from a mild inactive state to a rapidly progressive hepatitis. In certain individuals the infection causes complications more rapidly. 

HBV can be transmitted in several ways:

1. Around the time of birth from an infected mother ("perinatal")
2. By exposure to infected blood e.g. blood transfusion, sharing needles, open wounds
3. Sexual transmission

Chronic HBV infection usually occurs in individuals exposed to the virus early in life or in individuals with weakened immune systems.

Symptoms

• Patients with acute hepatitis B often have jaundice and are very unwell.
• Chronic infection is usually asymptomatic until complications arise. The infection may only be detected when donating blood or when abnormal liver results are found on blood tests.

Complications:

• Liver fibrosis and cirrhosis
• Liver failure
• Liver cancer
• Kidney disease

Treatment

• Acute HBV infection – Usually self-limited and resolves with supportive management only. Bed rest is crucial for faster recovery.
• Chronic HBV infection – Infection is not curable with currently available therapies. Treatment is aimed at suppressing replication of the virus using oral antiviral agents, thus preventing damage to the liver and the development of complications. It is also important to monitor individuals infected with HBV for the development of liver cancer. There are effective strategies for dealing with HBV infection, and infected individuals should always seek medical care from a specialist trained in the management of this condition, such as a gastroenterologist.

Immunization and prevention of infection

HBV infection can be prevented by vaccination. Since 1995 HBV vaccination has been part of the South African national immunization program. Transmission of HBV perinatally can also be prevented by using the correct therapy. It is advised that all adults who are at an increased risk of infection or are at risk of more severe infection should also receive vaccination. This includes patients receiving immunosuppressant drugs, as in Crohn's disease and ulcerative colitis.