Hepatitis

Introduction

The word "hepatitis" means inflammation of the liver. Rarely, some kinds of hepatitis are not caused by infection. These non-contagious types of hepatitis can result from alcohol abuse, certain drugs, ingestion of toxic substances, or autoimmune disease (the body's own immune system attacks the liver). The usual cause of hepatitis, however, is infection by a virus. At least six viruses, usually identified by the letters A through G, are known to cause hepatitis. In the United States, hepatitis A, hepatitis B, and hepatitis C are the most common.

Typically, hepatitis B and hepatitis C infections have distinct phases. The first, or acute phase, occurs soon after infection with the hepatitis virus and lasts for 6 months or less. Many individuals recover from acute hepatitis, and their livers return to normal within a few months. Depending on the type of hepatitis, however, some of the individuals who contract acute hepatitis infections may not be able to eliminate the virus. For these individuals, the acute infection may be followed by a chronic phase. Usually, chronic hepatitis involves a prolonged latent or inactive period. During this time, which may last 20 years or longer, individuals with hepatitis probably do not experience symptoms or feel ill. Generally, however, the virus continues to multiply, gradually causing liver damage. Typically, symptoms do not become apparent until liver damage is extensive. However, abnormal levels of liver enzymes such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) may show if liver tests are done.

What is it?

Hepatitis B is a specific type of hepatitis caused by the virus that has been designated as hepatitis B virus (abbreviated as HBV), which causes inflammation and damage to the liver. As the virus infects more liver cells, inflammation and destruction of liver cells can interfere with the functions of the liver.

Normal Liver Functions That May Be Affected by Liver Damage
Breakdown of harmful substances to keep them from building up in the bloodstream
Production of bile to help digest food
Production of cholesterol and protein
Regulation of blood clotting
Storage and release of energy in the form of sugar

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Most individuals are able to fight off (or clear) infection with HBV and they recover in 2 to 4 months. Ordinarily individuals only get hepatitis B once and after the HBV infection has been cleared, the individual has lifelong immunity . Up to 10% of adults, 50% of children under the age of 5, and 90% of infants who contract hepatitis B will not be able to eliminate the virus in 6 months. These individuals are considered to be chronic carriers of HBV.

It is estimated that chronic hepatitis B affects 1.25 million people in the United States and leads to 5,000 U.S. deaths per year. Chronic hepatitis puts individuals at a greater risk of developing cirrhosis or liver cancer. Cirrhosis is a condition that gradually replaces active liver cells with inactive scar tissue. Slowly, liver function is lost and liver failure may result. However, individuals who are chronic carriers of HBV but who have no symptoms are much less likely to develop cirrhosis than individuals who have chronic symptoms of hepatitis B.