In the Asia Pacific region Human Immunodeficiency virus (HIV) is often acquired in individuals already infected with hepatitis B virus (HBV). The immune suppression caused by HIV infection reduces cellular immune response against HBV and liver inflammation may improve, but the risk of developing cirrhosis is not. HBV infection does not affect the progression of HIV disease. Anti-retroviral agents may be directly hepatotoxic and cause ALT elevations in patients with chronic hepatitis. Highly active anti-retroviral therapy (HAART) improves immunity and as cytotoxic lymphocyte responses improve, hepatitis flares can occur, usually r within 3 months of initiation of HAART. These hepatitis flares may be followed by normalization of ALT and clearance of HBVDNA. If lamivudine is included in the HAART regime, hepatitis flares may not occur till late and these late flares signal the development of lamivudine resistant HBV strains (90% of HBV/HIV co-infection). Treatment options for chronic HBV infection include interferon (IFN), and nucleoside analogues. Lamivudine, adefovir dipivoxil, tenofovir disoproxil fumarate (DF) are nucleoside analogues with activity against both HBVDNA polymerase and HIV reverse transcriptase. The latter two compounds have added activity against lamivudine resistant HBVDNA. Lamivudine should be avoided in the initial treatment of both hepatitis B as well as HIV because of the high incidence of resistance. Interferon should be considered first for treatment of HBV in HIV co-infected individuals and is usually unsuccessful in the later stages of HIV infection when immune suppression is extreme. As new and improved agents in HAART continue to prolong survival, the use of liver transplantation for cirrhotic patients co-infected with HIV and HBV may increase.
The association of hepatitis B virus (HBV) infection and liver cancer is well documented in epidemiological study. Patients with chronic hepatitis B have increased risk of hepatocelluar carcinoma (HCC), in particular those with active liver disease and cirrhosis. The incidence of HCC increases with age and is more common among male patients. The introduction of universal HBV vaccination program for the newborn in endemic regions has started to show beneficial impact. Taiwan introduced this program two decades ago and the incidence of liver cancer among infants and young children have declined significantly. The carcinogenic events leading to HCC are under intense research. A number of hypotheses have been proposed. HBV is not directly hepatotoxic but its interaction with the host immune system creates opportunity for HBV DNA integration into the host genome. One of the main foci of research is the HBX-encoded X protein. Its integration and protein expression impose alteration in cell proliferation cycle and apoptosis process. Many other factors may be involved including viral-induced alterations in p53 and telemerase, HBV genotypes, co-infection with HCV or delta agents, patient's lifestyle such as smoking, alcohol excesses, and genetic factors of the host patient. The processes of necroinflammation, cell proliferation and fibrosis facilitate the initial carcinogenic development. HCC surveillance with tumor markers such as alpha-foetal protein, decarboxylated prothrombin, in conjunction with imaging techniques has identified early small HCC that is amenable to curative therapy. Viral load has been correlated with increase risk of HCC. The available anti-viral agents have demonstrated clinical benefit among those with maintained and sustained response. Interferon and lamivudine therapy have demonstrated reduction of HCC among responders. However, they only constitute a minority proportion of treated patients. The mainstay of prevention should lie in prevention of HBV infection and early effective therapy of chronic hepatitis B infection.
MeSH terms: Age Factors; Hepatitis B/complications; Hepatitis B/epidemiology*; Hepatitis B/prevention & control; Hepatitis B virus/immunology; Hong Kong/epidemiology; Humans; Liver Cirrhosis; Liver Neoplasms/etiology; Liver Neoplasms/epidemiology*; Risk Factors; Comorbidity*; Hepatitis B Vaccines*; Immunization Programs
Liver transplantation has been successfully used in the treatment of a large number of liver diseases. The largest patient group comprises patients with end stage decompensated liver disease. Decompensation is defined as the presence of cirrhosis and one or more of the following: jaundice, ascites, hepatic encephalopathy, hepatorenal syndrome or bleeding oesophageal varices. In general patients in this category should be considered for liver transplantation, if available. Guidelines for liver transplant assessment have been published by both the British Society of Gastroenterology and the American Association for the Study of Liver Disease. These guidelines provide a good basis for patient selection. As new information becomes available the indications for individual diseases may change somewhat. One of the most important changes in recent years was the introduction of the MELD/PELD scoring system. This is the model for end stage liver disease which provides a reasonably robust estimate of prognosis for individual patients. Prior to this patient waiting time on the transplant list was one of the principal determinants of priority for liver allocation. The MELD scoring system has been widely adopted with the aim of allocating the available livers to patients in the greatest clinical need.
MeSH terms: Humans; Liver Diseases/classification; Liver Diseases/surgery*; Time Factors; Waiting Lists; HIV Infections; Comorbidity; Liver Transplantation*; Patient Selection*
Chronic pancreatitis is a difficult disease to treat. Worldwide, alcohol is the most common aetiology but based on recent studies it is clear that genetic susceptibility plays an important role in determining disease. Several important genetic mutations have been identified. The prevalence of chronic pancreatitis appears to be lower in Asia although very high rates have been reported in parts of India. Severe intractable pain is the predominant presenting complaint of patients. The natural history of the disease and the onset of exocrine and endocrine insufficiency depend on the classification of disease as early onset, late-onset or alcohol associated. Complications of chronic pancreatitis are important and include pseudocyst formation, bile duct and duodenal strictures.
Hepatitis A, an acute usually self limiting infection of the liver is one of the most common vaccine-preventable infectious disease in the world. Effective vaccines which provide long term immunity against hepatitis A have been available since 1992. They are of known good quality, well tolerated with no serious adverse events and have been successfully used to protect different populations from infection as well as interrupt outbreak in closed communities. Mathematical models estimate the long term persistence of antiHAV antibodies to be more than 25 years. Vaccination efforts should be supplemented by health education and improved sanitation. Planning for large scale immunization programmes against hepatitis A should take into consideration epidemiological and cost benefit studies.
MeSH terms: Acute Disease; Adolescent; Adult; Child; Child, Preschool; Communicable Disease Control; Hepatitis A/immunology; Hepatitis A/prevention & control*; Humans; Immunization, Passive; Infant; Vaccination; Hepatitis A Virus, Human/immunology; Hepatitis A Vaccines/adverse effects; Hepatitis A Vaccines/immunology*; Hepatitis A Antibodies