(Science: virology) a form of viral hepatitis, known as serum hepatitis, because it is commonly spread through contact with infected blood products (transfusion). May also be spread sexually or from mother to infant. Hepatitis b can cause a much more severe infection than hepatitis a and can occur as an asymptomatic carrier state, a chronic infection or as cirrhosis of the liver. Those at risk (iv drug abusers, health care workers, dialysis patients, transfusion recipients, homosexuals) should be immunised with hepatitis b vaccine.
The virus is 42nm diameter, with an outer sheath enclosing inner 27nm core particle containing the circular viral dna. Aggregates of the envelope proteins are found in plasma and are referred to as hepatitis b surface antigen (HBsAg, previously called australia antigen). The virus can persist for long periods (and in asymptomatic carriers), association of integrated virus with hepatocellular carcinoma is now well established.