Chronic viral hepatitis

Hepatitis is inflammation. The term is most commonly used in relation to disease caused by viruses.

The common Hepatitis viruses are:

• Hepatitis A: Common epidemic hepatitis. In the recent past (say 50 years ago) most people caught it and most of those who caught it were not aware of it. I am not sure of current figures but antibodies to the disease are still very common. Some people get a quite severe illness with jaundice but full recovery is the rule. A vaccine is now available. Hyper-immune serum (it used to be just normal pooled serum) will protect against the disease for a few months.

• Hepatitis B: This is a very common disease in some communities (eg Chinese, Pacific Islanders, Maoris) but relatively rare in Western society. It is transmitted by blood and body fluids and vertically (Mother to baby).

It was once called 'Australia antigen' because it was first found in an Australian aborigine's blood.

Some people catch the disease, fully recover and become immune and are non-infectious.

Some people catch the disease and it persists in their body. These people remain infectious and are called carriers. There is a significant long term risk of cirrhosis and hepatocellular cancer[?]. (This is the commonest cancer in China). Carriers can occur at all ages but are more common when the disease is caught in childhood.

There is some protection from hyper-immune serum. There is an effective vaccine.

• Hepatitis C: This used to be called non-A non-B hepatitis. It is caused by a flavi-virus relative and is transmitted by blood and possibily by some other mechanism as yet unknown. In Western societies it is increasingly being spread by intra-venous drug use. There is a significant risk of cirrhosis and hepatocellular carcinoma. A high proportion of people exposed remain infectious (??figure).

• Hepatitis D: or 'delta' agent. This is an RNA passenger virus that requires a co-infection with hepatitis B. The combined disease is usually more serious. As far as I know there is no vaccine.

• Hepatitis E. This is a hepatitis that resembles Hepatitis in many respects but some patients get an extremely severe illness with complete death of the liver. It is mostly described on the Indian subcontinent. As far as I know there is no vaccine.