Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus. It is a major global health problem and the most serious type of viral hepatitis. It can cause chronic liver disease and puts people at high risk of death from cirrhosis of the liver and liver cancer.
Worldwide, an estimated two billion people have been infected with the hepatitis B virus (HBV), and more than 350 million have chronic (long-term) liver infections.
Hepatitis B virus can cause an acute illness with symptoms that last several weeks, including yellowing of the skin and eyes (jaundice), dark urine, extreme fatigue, nausea, vomiting and abdominal pain. People can take several months to a year to recover from the symptoms. HBV can also cause a chronic liver infection that can later develop into cirrhosis of the liver or liver cancer.
Hepatitis B virus is transmitted between people by contact with the blood or other body fluids (such as semen and vaginal fluid) of an infected person. Modes of transmission are the same for the human immunodeficiency virus (HIV), but HBV is 50-100 times more infectious. Unlike HIV, HBV can survive outside the body for at least 7 days. During that time, the virus can still cause infection if it enters the body of a person who is not infected.
Carriers of HBV are capable of transmitting the disease, though often remain asymptomatic and may not be aware that they are infected.
Common modes of transmission in developing countries are:
- perinatal (from mother to baby at birth);
- early childhood infections (unapparent infection through close interpersonal contact with infected household contacts);
- unsafe injections practices;
- needle-stick injury;
- blood transfusions;
- sexual contact; and
- nosocomial transmission in overseas healthcare facilities if infection control procedures are unsatisfactory.
HBV is a major infectious occupational hazard of health workers. HBV is not spread by contaminated food or water, and cannot be spread casually in the workplace.
The virus incubation period is 90 days on average, but can vary from about 30 to 180 days. HBV may be detected 30 to 60 days after infection and persist for widely variable periods of time.
There is no specific treatment for acute hepatitis B. Care is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids that are lost from vomiting and diarrhoea.
Chronic hepatitis B can be treated with drugs, including interferon and anti-viral agents, which can help some patients. Treatment can cost thousands of dollars.
Liver cancer is almost always fatal, and often develops in people at an age when they are most productive and have family responsibilities.
All children and adolescents younger than 18 years old and not previously vaccinated should receive the vaccine.
People in high risk groups should also be vaccinated, including:
- persons with high-risk sexual behaviour;
- partners and household contacts of HBV infected persons;
- injecting drug users;
- persons who frequently require blood or blood products;
- recipients of solid organ transplantation;
- those at occupational risk of HBV infection, including health care workers; and
- international travellers to countries with high rates of HBV.