The Alphabet Soup of Virus Hepatitis: Hepatitis B
What is Hepatitis B?
Hepatitis B is a major public health problem in the Asia Pacific region where three quarters of the whole world’s chronic Hepatitis B patients live. Hepatitis B is a DNA virus with a number of sub-types that have some relevance to the severity of hepatitis and the response to treatment.
How is Hepatitis B acquired?
The virus is acquired through being injected into the body. Common routes include intravenous drug abuse and blood transfusions in places where good screening of the blood is not done. Hepatitis B is also easily acquired through sexual intercourse and contact with body fluids. Mothers who have chronic Hepatitis B can transmit the virus to their new-born babies at the time of birth. This is an important means of transmission in our region.
What are the symptoms?
There is an incubation period between acquiring the virus and showing clinical symptoms. This period is between 40 and 180 days. The larger the number of viruses acquired, the shorter is the incubation period. Hepatitis B can cause an acute hepatitis with significant un-wellness and jaundice during which the virus is cleared by the body’s immune system and antibodies are developed that protect against future infection. However, the earlier in life the virus is contracted, the more likely it is to become chronic, which as described in another article, has few symptoms until a late stage.
What is the outcome?
In our region, due to vertical transmission between mother and new-born baby and young age transmission, more than 90% of these young persons end up with chronic hepatitis (see other article on what is chronic hepatitis). On the other hand, if the infection is acquired as an adult, more than 90% will recover completely. Fulminant hepatitis occurs in about 2% of patients.
Can it be treated?
Most patients at the time of diagnosis have chronic hepatitis. The aim of treatment is to reduce virus replication so as to prevent further damage to the liver, reduce infectivity (especially important for mothers to reduce transmission to new-borns) and reduce the risk of liver cancer. Treatment is most urgent when there is evidence of on-going liver inflammation and cell damage, indicated by elevated liver enzymes such as ALT and AST. A 3-6 month period of monitoring is often undertaken to see if the patient’s own immune system can overcome the virus and effect a cure. If not, then treatment can proceed.
What is used to treat Hepatitis B?
The treatment of Hepatitis B has evolved over the years. In the past, the mainstay was a natural protein molecule called Interferons, initially injected three times a week below the skin and later, with the advent of “pegelated” interferons, once weekly, for about a year. Interferons cause severe side effects such as a ‘flu syndrome, fatigue, loss of appetite, weight loss, reduction of blood counts and depression. It was also dangerous in patients with liver cirrhosis, as the body’s reaction may cause fulminant hepatitis. However the course of treatment is finite and if it works, a long term cure with immunity is achieved.
More recently, a number of antiviral drugs have been developed and licensed for use in Hepatitis B. When to use these drugs depend on many factors, including the degree of liver inflammation, the amount of virus in the blood and the types of antibodies relating to different parts of the virus that are present or absent (e.g. HBs Ag and Ab, HBe Ag and Ab etc.). A proper analysis by a specialist is required.
These drugs suppress viral replication, but seldom effect a permanent cure. If the drugs are stopped, a good proportion of patients will suffer relapse. Hence the drugs need to be taken for many years, sometimes lifelong. These drugs are safe in liver cirrhosis unlike interferons.
Available drugs include Lamivudine, Adefovir, Entecavir and Tenofovir. The latter two are more resistant to the development of viral resistance and are nowadays most commonly used.
Can I vaccinate against it?
Passive antibodies or immunoglobulins are helpful to immediately neutralise viruses that have entered the body, such as by injection or during childbirth. Active vaccination is also available for Hepatitis B. It is safe and effective and is now part of the schedule of routine childhood vaccinations which includes universal immunisation at birth. This has resulted in a dramatic reduction of Hepatitis B transmission in areas where the virus is common (endemic). Three injections over six months are needed and after the third the rate of protection is >95%. For adults who were not vaccinated when young, indications for vaccination include
- Persons at high risk of infection by injection or exposure to blood or body fluids such as intravenous drug abusers, household contacts of infected persons, residents and staff of institutionalised persons, healthcare or public safety workers and persons with end stage kidney disease.
- Persons at risk of infection by sexual exposure
- International travellers to regions with high endemicity
- Persons with other chronic liver sieases
- Persons with HIV infections