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Hepatitis B infection
Hepatitis B is caused by a virus called the Hepatitis B virus (HBV). It is the most common serious infection of the liver in the world. It is a contagious liver infection with varied natural causes in different individuals.
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The first six months after a person becomes infected is called the acute Hepatitis B infection in which many people show no symptoms at all or may present with mild feeling of unwell.
Most people will not recognise that they have liver disease during this phase. In over 90 per cent of persons who become infected as adults with Hepatitis B, the immune system successfully fights off and clears the virus from the body within six months.
Any damage done to the liver heals completely with development of immunity to Hepatitis B infection for the rest of their life. In less than 10 per cent of patients, the immune system is unable to clear the virus and Hepatitis B infection persists beyond six months, usually for the rest of the person’s life, as chronic Hepatitis B infection. This is completely opposite to what is observed in babies who become infected at birth or during infancy. In their case, only about 10 per cent will clear the infection, with the remaining 90 per cent developing chronic Hepatitis B infection.
In chronic Hepatitis B infection, the liver becomes inflamed and scarred over a period of years. However, the speed at which inflammation and scarring takes place varies between people. Some develop severe liver scarring (cirrhosis) within 20 years.
In others, liver disease progresses slowly and does not become a major problem during their lifetime. About two-thirds of people with chronic HBV infection are chronic carriers. These people do not develop symptoms, even though they harbour the virus and can transmit it to other people. The danger of Hepatitis B is that it is associated with liver cancer in later life.
The Hepatitis B virus is a blood-borne virus because it is transmitted from one person to another via blood or fluids contaminated with blood. Another important route of transmission is from an infected mother to a newborn child (vertical transmission), which occurs during or shortly after birth. The Hepatitis B virus is 50 to 100 times more infectious than HIV and an important occupational hazard for health workers who handle or encounter these bodily fluids in their line of duty.
Direct contact with blood may occur using dirty needles during illicit drug use, inadvertent needle stick injuries experienced by healthcare workers or contact with blood through other means. Semen, which contain small amounts of blood, and saliva that is contaminated with blood also carry the virus. The virus may be transmitted when these fluids come in contact with broken skin or a mucous membrane (in the mouth, genital organs, or rectum) of an uninfected person. Kissing is a recognised mode of transmission of HBV.
People who are at an increased risk of being infected with the Hepatitis B virus include the following:
• Men or women with multiple sex partners, especially if they don't use condom
• Men who have sex with men
•Men or women who have sex with a person infected with Hepatitis B virus
• People who inject drugs with shared needles
• People who receive unscreened transfusions of blood or blood products
• People who undergo dialysis for kidney disease
• Health care workers with injuries from needles or other sharp instruments contaminated with infected blood
• Infants born to infected mothers
• Hepatitis B cannot be contracted through hugging, sneezing or coughing, handshaking or casual contact with an infected person.
Once somebody has come into contact with this virus, the conventional test done for Hepatitis B will test positive. The only way to ascertain whether a positive test to HBV is of acute origin or chronic in nature or not is to do the Hepatitis B profile as well as the viral loads. The HBV profile tests the presence of antibodies to certain specific parts of the virus known by letters of the alphabets such as c and s antigens.
Testing for exposure to the HBV is usually done by doing the Hepatitis B surface antigen (HBsAg). The drawback of this test is that it only shows that the person has been exposed to the HBV but does not indicate whether the person has acute disease or chronic disease. To differentiate between active disease and prior exposure which has been cleared by the body, the Hepatitis B profile test must be done.
This test tests for the presence of certain antibodies produced by the body to attack certain parts of the virus, the presence or otherwise is used to determine active or chronic disease. For example, if HBsAg, anti-HBc and anti-HBs results are all negative, then it means that the individual has not come into contact with the virus and so is susceptible or prone to infections by the virus. In the same vein if
HBsAg is negative but anti-HBc and anti-HBs are both positive, then it means that the person has been exposed to the virus but the immune system has cleared the virus, conferring immunity from the natural infection.
I will discuss prevention and treatment next week.
The Mirror doctor is a member of the Paediatric Society of Ghana
E-mail: [email protected]
