Hepatitis B virus ( HBV ) is the most common human hepatitis virus in Singapore. HBV infection and its chronic sequelae are major world-wide health problems. There are approximately 300 million chronic HBV carriers in the world, of whom 75% are found in the Asia Pacific region. It is estimated that between 25 to 50 percent of these carriers can expect to die prematurely, either as a result of chronic liver inflammation and liver failure (cirrhosis) or the development of liver cancer.
6% of the Singapore population are hepatitis B carriers. Most hepatitis B infection is acquired during birth and in early childhood. These infections are generally asymptomatic. These carriers remain well for long periods and are discovered incidentally during blood donation, health screening or screening prior to vaccination. While the number of acute hepatitis B has decreased over the years, largely as a consequence of universal vaccination and screening of blood donors, doctors still have to deal with problems of chronic liver inflammation, liver cirrhosis and cancer.
A baby who acquires the hepatitis B infection manifests a different course of illness from one who is infected in adulthood. Generally, an infection contracted at birth (from mother-to-child), does not manifest in any symptoms. Following such an infection the baby has a 90% chance of becoming a hepatitis B carrier, because they are unable to eliminate the virus from their bodies.
On the other hand, an individual who acquires the infection as an adult displays symptoms of "acute liver inflammation" (acute hepatitis B). Of these patients, 1% develop a very serious clinical course known as fulminant viral hepatitis B. These patients deteriorate very rapidly during the clinical course of the illness and may go into liver failure or even die. However, newer modalities of treatment like liver transplantation exist.
The symptoms of acute hepatitis B include:
Treatment in the acute period of the illness is essentially symptomatic relief of symptoms like itch, nausea and vomiting. It is generally advisable for patients with severe symptoms or deep jaundice to be admitted to hospital for observation because of the potentially severe consequences (fulminant hepatitis ) which may prove to be fatal, albeit rarely. This enables rapid intervention, which may be lifesaving, to be instituted if required. The patient is advised bedrest, and avoidance of alcohol and traditional Chinese remedies which could exacerbate his condition.
A chronic hepatitis B carrier goes through 3 phases, especially if the infection is acquired at birth. This is the usual scenario amongst carriers in Singapore:
High viral replicative ( immune-tolerant ) phase which is usually seen in patients less than 20 year old. There is rapid viral replication but the patient is well and has no symptoms. Blood tests and liver samples indicate minimal liver inflammation.
Low viral replicative (immune-elimination ) phase which occurs in patients between 20 to 40 years old. In this phase, the body's immune system attempts to rid itself of the hepatitis B virus, and this is reflected by abnormal blood tests that indicates active liver inflammation. The carrier may complain of lethargy. Occasionally, if this phase occurs in older patients, especially if more than 60 years, the clinical course is more serious and can cause severe liver dysfunction and death.
Non-replicative ( latent infection ) phase occurs in carriers above the age of 40 years. This phase is characterised by the continuous presence of the hepatitis B virus with a low replicative rate. There may be however, evidence of liver damage which later progresses on to liver cancer. The patient in this last phase may present for the first time with swelling of legs and abdomen, progressive mental deterioration and vomiting or passing out of blood in the stools.
Hepatitis B is best prevented by vaccination. The following groups who are at highest risk for contracting hepatitis B should be vaccinated:
Side-effects of vaccines are rare and include local soreness at the injection site, mild fever, malaise but extremely infrequently may cause swelling of the lymph nodes (glands in the neck, groin, armpits ), and abnormalities of the nervous system.
The vaccine is administered at time 0,1 and 6 months. However, before one gets vaccinated, one should check oneself for the immune status. Only those who are non-immune to hepatitis B and not carriers should be vaccinated.
Although we would expect the number of hepatitis B carriers to decrease in time, largely due to widespread screening and immunisation efforts, there still exists a significant proportion of our population who are carriers. The treatment of these carriers include:
I) Diagnosis and evaluation
Blood tests, ultrasonography of the liver and liver tissue sampling ( liver biopsy ) are used to assess the severity and stage of the illness. In suitable patients, appropriate treatment e.g. interferon may be instituted.
i) General Advice
II) Supportive therapy
The aim of specific therapy is to reduce infectivity, stop the progression of the disease and ultimately prevent complications like cirrhosis ( 'liver failure with hardening' ) and cancer. These are basically 2 groups of drugs that are used by liver specialists, namely:
Only alpha-interferon is registered, the rest are on trials at the Singapore General Hospital (SGH). Suitable hepatitis B carriers are treated with alpha-interferon. (To learn more about alpha-inteferon, see Hepatitis C treatment). Clinical trials using alpha-thymosin, famcyclovir, lamivudine are being conducted in SGH. The current success rate in the treatment of chronic hepatitis B is 30 - 40% using alpha-interferon. Interferon is costly, and has side effects.
III) Monitoring of hepatitis B carriers
Hepatitis B carriers should be followed up regularly at intervals depending on the stage of the disease. Besides monitoring the disease activity or progression, the patient is screened for liver cancer. The risk is estimated to be 200 times greater amongst hepatitis B carriers as compared to non-carriers. During such visits, besides a clinical examination, the patient is subjected to blood tests which includes an alpha-fetoprotein level. Alpha-fetoprotein is a tumour marker for liver cancer. Ultrasonography of the liver is usually performed at 6 - 12 monthly interval depending on the stage of the disease. These measures ensure that if a cancer is detected, the likelihood of it being early and curable is considerably higher.
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