Most damage from hepatitis B virus (HBV) is caused by the body's response to the infection. This immune response against the infected liver cells (hepatocytes) damages the cells, causing the liver inflammation known as hepatitis.

As a result, liver enzymes (transaminases) leak out of the liver into the blood, causing transaminase blood levels to be elevated. The virus impairs the liver's ability to produce the clotting factor prothrombin, increasing the time required for blood clot formation (prothrombin time).

Liver damage also impairs the body's ability to rid itself of bilirubin (a breakdown product of old red blood cells), causing jaundice (yellow discoloration of the eyes and body) and dark urine.

In a small percentage of patients, an overly vigorous immune response to the infection leads to fulminant hepatic failure.


Symptoms

Additional symptoms that may be associated with this disease:

• nosebleed
• depression

Treatment
There is no treatment for acute HBV infection. Interferon-Alfa and lamivudine are the two FDA-approved antiviral drugs used for chronic HBV infection.

There are two types of chronic infections: the replicative phase where there is active reproduction of the HBV virus in the liver resulting in severe chronic hepatitis with the person being very infectious; and the non-replicative phase where there is very minimal liver injury.

Interferon and lamivudine are only recommended for those with chronic replicative HBV infection. Interferon is given over a four-month period either on a daily or three times per week basis. About 40% of patients treated with interferon will have a positive response.

Another drug, thymosin alpha-1, has been approved in countries outside the US and has shown considerable promise as a booster to the immune system's own defenses against Hepatitis B. Studies are ongoing in the US to gain FDA approval.


Prevention

Immunisation
Hepatitis B is a preventable disease. 10% of people who get hepatitis B do not recover completely. They become hepatitis B carriers who appear well but carry the virus and spread the virus to others.

Hepatitis B carriers may develop complications such as chronic hepatitis, liver cirrhosis, liver failure and liver cancer.

Those who recover completely from hepatitis B infection are immune for life.

Immunisation is recommended for all persons and currently, all newborns born in hospitals are immunised.

The HBV vaccine provides protection for up to 15 years and is considered to be safe and effective. It is given in three injections scheduled at 0, 1, and 6 months. For babies born to infected HBV mothers, hepatitis immune globulin (HBIG) is given immediately after birth, followed by the first dose of the hepatitis B vaccine.

Avoiding high risk activity
Hepatitis B virus is carried in the blood and body fluids and can be spread by high risk activities which should be avoided:

• sexual contact with a carrier or an infected person
• use of contaminated skin piercing instruments such as in acupuncture, body piercing, tattooing and the sharing of injection needles.