Hepatitis B virus is a DNA virus with a exceptionally compact structure. It consists of a core containing DNA and an enzyme for its replication(DNA Polymerase). A surface protein surrounds the core of the virus. Humans are the only source of infection.Hepatitis B infection affects 300 million people and is one of the most common causes of chronic liver disease and liver carcinoma world-wide.
Infection with Hepatits Virus B often produces no symptoms. Sometimes the chronic infection with the same virus also has no symptoms. Chronic liver damage may occur in chronically infected persons after decades of initial infection.
The highest risk of progression of the infection to chronic liver disease is for a baby born from an infected mother. This transmission is the most common way by which Hepatits B spreads.
For Hepatitis B Virus, the existence of inactive hepatitis B carriers with normal liver histology and function suggests that the virus is not directly cytopathic. Patients who have a low cellular immunity more likely to remain chronically infected rather than to clear Hepatitis B Virus.
Symptoms and Signs
Acute viral hepatitis occurs after an incubation period that varies from 30–180 days. The symptoms of acute viral hepatitis are variable. Patients may present with symptoms like anorexia, nausea and vomiting, fatigue, joint pain, muscle pain, headache, sore throat, cough, and cold which may be followed by the development of yellow discolouration (jaundice). Fever in Hepatitis B is usually low grade or absent. Dark urine and stools may be noticed by the patient from 1–5 days before the onset of yellow discolouration (jaundice).
When jaundice appears the symptoms gradually recede. There is an upper abdominal discomfort or pain. Spleen might get enlarged in some patients along with enlargement of lymph nodes. This if followed by recovery in about 3-4 months.
Some patients with infection with Hepatitis B become super infected with Hepatitis D.
How will you investigate for Hepatitis B?
In acute infection the hepatitis B surface antigen (HBsAg) is a reliable marker of Hepatitis B Virus infection, and a negative test for HBsAg makes Hepatitis B Virus infection very unlikely.
Antibody to surface antigen (Anti-HBs) implies that the person is previously vaccinated, however if it is present along with Anti-HBc then the person is usually infected in the past by Hepatitis B Virus.
Chronic Hepatitis B Virus infection is marked by the presence of HBsAg and anti-HBc (IgG) in the blood.
Treatment?
For Acute cases there is no treatment except prolonged best rest with good nutritional support.
For chronic hepatits B treatment is limited to various anti-viral drugs, necleotide and nucleoside analogues. Liver transplantation is often considered in severe cases.
Who are at risk of getting infected with hepatitis B virus?
- Parenteral drug users
- Close contacts of infected individuals
- Newborn of infected mothers
- Regular sexual partners
- Patients on chronic haemodialysis
- Medical/nursing personnel
Prevention from Hepatitis B Virus?
Vaccination: A recombinant hepatitis B vaccine containing HBsAg (Engerix) is capable of producing active immunization in 95% of normal individuals. However the vaccine is ineffective in those already infected by Hepatitis B Virus.
Passive Immunity: Intramuscular injection of hyper-immune serum immunoglobulins prepared from blood containing Anti-HBs.
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