What is Hepatitis B virus?
Hepatitis B virus is a disease of the Liver. Hepatitis refers to any condition causing inflammation of the liver. Although many Hepatitis B viruses can cause inflammation of the liver, Hepatitis B is one of six viruses that specifically target the liver – which is why they are called Hepatitis viruses. The Hepatitis B viral particle is made up of an outer surface coat – hep B surface antigen (HBs), inner core ds DNA (hep b core antigen – HBc), and hep e antigen (HBe). These parts of the Hepatitis B virus particle and the antibodies produced against them by the body are used for laboratory detection of the virus.
Statistics on Hepatitis B virus
Hep B is prevalent world-wide and has infected more than 2000 million people, with about 300 million carriers. The disease is more common in South-East asia and Africa. While the rate of carriage of Hepatitis B is 0.1% in the UK, it is as high as 20% in some areas of Asia and Africa. In those areas Hepatitis B carriage is perpetuated by spread from mother to baby during birth.
Risk Factors for Hepatitis B virus
The Hepatitis B virus is found in body secretions.
- Hepatitis B can be spread intravenously (e.g. by transfusion of infected blood, blood products, or by contaminated needle used by drug addicts, tattooists or acupuncturists)
- By close personal contact (e.g. in unprotected sexual intercourse).
- The Hepatitis B virus can also be transmitted from mother to child during parturition or soon after birth.
Progression of Hepatitis B virus
- The incubation period of infectious Hepatitis B can be as long as 2-3 months.
- Acute hepatitis can then develop. This can be severe – causing massive liver necrosis (death of liver cells).
- Around 95% of patients will then recover completely, however 5-10% will develop chronic carriage – where they do not complete control the infection and the virus continues to replicate in liver cells.
- This can be symptomless, or lead to chronic active hepatitis in 3% overall- continuing liver inflammation which can lead to progressive liver failure. Hepatitis D (delta agent) can contribute to the development of this.
- Hepatitis B is also an important risk factor for liver cancer – hepatocellular carcinoma, especially in areas such as Asia and Africa where the infection is acquired often at a young age.
How is Hepatitis B virus Diagnosed?
- Hepatitis B surface antigen detected.
- Hepatitis B core antibody detected 1-2 weeks after first detection of surface antigen.
- Hepatitis B surface antibody.
- Both hepatitis B surface antibody and core antibody persist indefinitely in the blood of patients who have recovered from hepatitis B.
- Your liver enzyme blood levels may be elevated due to sustained liver damage.
Prognosis of Hepatitis B virus
- 95% of adults recover completely from Hepatitis B. 1-10% will develop chronic disease.
- In areas of high endemicity, 80% will become chronic carriers.10-30% of those who develop chronic infection develop chronic liver disease.
- One percent of Hepatitis B patients proceed to acute fulminant liver failure. Hepatitis B is the most important cause of fulminant hepatitis worldwide. Even with the improved survival of liver transplantation, mortality exceeds 60%.
Hepatitis B virus Prevention
- Avoid risk behaviours
- Hepatitis B Vaccination – recommended for those at risk – homosexuals, healthcare workers, those travelling to high risk areas, drug abusers and haemodialysis patients
- Post-exposure for non-immunised individuals: (sexual partners, needle stick injury, infants of mothers who are Hepatitis B Ag positive)
- Hepatitis B Immunization plus specific antihepatitis immunoglobulin
How is Hepatitis B virus Treated?
Treatment of the infected patient:
- Supportive, avoid alcohol.
- Interferon alpha – administered 3 times a week by the patient (subcutaneously) for 4-6 months. Stimulates immune system to clear virus (clear HBe Ag and HBV DNA). Achieved in approximately 50% of cases.
- Other antivirals – lamivudine and famciclovir.
For more information on different types of sexually transmitted infections, prevention of STIs, treatments and effects on fertility, see Sexually transmitted infections (STIs).
Hepatitis B virus References
- Kumar P, Clark M. CLINICAL MEDICINE. WB Saunders 2002.
- Longmore M, Wilkinson I, Torok E. OXFORD HANDBOOK OF CLINICAL MEDICINE. Oxford Universtiy Press. 2001.
- McLatchie G and Leaper DJ (editors). Oxford Handbook of Clinical Surgery 2nd Edition. Oxford University Press 2002.
- Raftery AT Churchill’s pocketbook of Surgery. Churchill Livingsone 2001.
- Timbury, MC. Notes on Medical Virology, 11th Ed.