This original paper was written by Dr. Florence Wong, Gastroenterologist at The Toronto Hospital in Ontario, Canada.
Hepatitis B is a virus that infects the liver. Is estimated that 350 million people are infected with hepatitis B worldwide, with 50 million new cases diagnosed annually. The carrier rate of hepatitis B varies widely, being uncommon amongst Westerners, but reaching as high as 20% in people from Asia and Africa. Thus, the disease is very common amongst Chinese. With immigration of Chinese into Western countries, hepatitis B is now becoming established in countries where it was previously uncommon.
Approximately 10 percent of patients contract hepatitis B as an adult and that is usually the case amongst Westerners. In the Chinese population, hepatitis B is usually transmitted from infected mother to the newborn infant. Because of the immature immune system in these infants, they cannot clear the virus from their bodies. They therefore remain infected for life. Such infected individuals act as potential reservoirs of infection and can transmit the disease through kissing, sharing of toothbrushes, razors and sexual contact. Hepatitis B can also be transmitted through blood transfusion, although the incidence of this happening is very low now since routine screening of blood donations. Intravenous drug users who share needles with others and health-care workers who handle blood samples are also at high risk of contracting hepatitis B.
Currently, it is estimated that approximately 20 percent of the Chinese population are infected with hepatitis B. Many infected individuals cannot remember being ill with hepatitis. The virus may remain dormant and these people are usually a symptomatic and therefore referred to as healthy carriers. However, a significant portion of patience may have ongoing liver damage despite remaining asymptomatic. Occasionally their liver inflammation can be so severe that the patient feels ill with nausea, loss of appetite and becomes jaundiced. Repeat episodes of liver damage will lead to scarring of the liver called cirrhosis which will lead to many complications including the development of liver cancer.
Because many patients with liver inflammation remain asymptomatic, they may progress to liver cirrhosis or even liver cancer silently. Therefore it is important for the Chinese population to be screened for hepatitis B. Once hepatitis B is diagnosed, the treating physician will determine from various investigations and abdominal ultrasound the extent of liver inflammation. If the patient has normal liver function tests as well as a normal and abdominal ultrasound, he needs to be followed up regularly by his family physician since it is totally unpredictable when the virus will become active. Blood tests are recommended every six months and abdominal ultrasound every year. The patient should also be screened for the presence of liver cancer, especially in males older than 40 years of age. Should liver inflammation be detected, patient should be referred for a specialist opinion. The specialist will undertake further investigations which may include a liver biopsy to determine the extent of inflammation and cirrhosis. Treatment is now available for hepatitis B and it should be offered to patients who have persistence inflammation for more than six months. Once cirrhosis is established treatment is less effective. Therefore, patients should be screened and treatment offered before a there is any significant liver damage.
Approved treatment for hepatitis B is Interferon given over a period of 16 weeks during which time the patient is closely monitored. Treatment with Interferon is associated with some side effects which tend to settle down after the initial few weeks. The dose of Interferon may be reduced should the side effects become intolerable. Approximately 50 percent of patients treated with Interferon will a favorable response with the virus being converted from the active to be inactive form. Treatments are now being developed for those patients who were unsuitable for Interferon treatments or have failed Interferon treatment. These are still currently being used in investigational studies.
Once an index case of viral hepatitis B is identified, the entire family should be screened for hepatitis B. Some members of the family may have been infected but cleared the virus and therefore have become immune. Other members may be chronic carriers, while others may still be unexposed to the virus. those individuals who have cleared the virus do not require further medical attention. Those individuals not yet exposed to the virus should be vaccinated against hepatitis B while chronic carriers need to be cared in the same way as the index case. Vaccination against hepatitis B is very effective and consists of the course of three injections. Vaccination can be arranged with the family physician. Once the course is completed, the individual is protected for life. Currently various provincial governments have agreed to fund vaccination for children in grades 7. It is recommended that all children in communities with high carrier rates, such the Chinese community, should be vaccinated from birth or as soon as possible once they have been screened and found to be unexposed. Is only with a mass vaccination program that we can hope to eradicate hepatitis B in the next generation.
Viral Hepatitis C Infection
Hepatitis C virus is another virus which infects the liver. It is made up of a family of similar viruses and they are structurally different from the hepatitis B virus. The distribution of hepatitis C infection differs from that of hepatitis B in that it is particularly prevalent in certain countries such as Japan, Korea, Vietnam and China. It is mainly transmitted through contact with infected blood. Therefore, patients who required transfusion of blood and blood products are risk, together with patients who have had injections with shared needles. Unlike hepatitis B, infection with hepatitis C usually occurs in adulthood. Once infected, the majority patients will not be able to get rid of the virus, but rather will have ongoing inflammation ultimately leading to cirrhosis. Hepatitis C is a very slow growing virus and this process of smoldering inflammation may take 20 years before symptoms develop. Certain subgroups of patients tend to have a more rapid progression of the disease leading to cirrhosis in a few years and these are usually patients who contracted the disease at an older age, patients who abuse , alcohol and patients who also have hepatitis B infection. Once symptoms develop, the liver disease is usually quite advanced and complications of cirrhosis are usually present. Therefore, it is important to screen patients from high prevalence countries for hepatitis C, even at the asymptomatic stage, so that treatments can be offered before the development of cirrhosis.
Once the patient is diagnosed to have hepatitis C infection, investigations including blood test and ultrasound and the liver biopsy will be performed to determine the severity of the inflammation and to assess for the presence of cirrhosis. Screening for liver cancer is also performed since patients infected with hepatitis C also are at higher risk for the development of liver cancer.
The currently recommended treatment for hepatitis C infection is Interferon. Like hepatitis, the treatment is more effective before the development of cirrhosis. Our present experience recommends treatment for a period of 12 months. Side effects tend to be less severe since these patients require a lower daily dose than those being treated for hepatitis B. The response rate to Interferon as approximately 30% after one year of treatment. Recently, a new anti-viral agent in the form of an oral medication, has been used in combination with Interferon with improved response rates. Patients being treated with Interferon for hepatitis C with or without the oral agent, need to be monitored regularly. Successful treatment will suppress liver inflammation and convert the patient from an active phase to a dormant phase of the disease. This will slow down progression to cirrhosis and also reduce the risk of the development of liver cancer.
Currently, there is no available vaccination against hepatitis C infection. The only effective prevention is to avoid contact with infected blood. Current practices with blood transfusion should make the risk of contracting viral hepatitis C minimal. Patients who are infected should not share their razors toothbrushes, or shavers. Sharing needles should also be avoided. Patients with hepatitis C should not drink alcohol, because the combination of alcohol and hepatitis C will accelerate the progression to cirrhosis and even increase the risk of liver cancer. Currently, Hepatitis C infection is the biggest epidemic worldwide. Active screening and treatment of suitable cases is the only possible means of controlling this problem.