Hepatitis B

Definition

The term "hepatitis" refers to syndromes or diseases causing liver inflammation, including inflammation due to viruses and chronic alcohol abuse. Viruses causing hepatitis include Hepatitis A, B, C, E and the delta factor. Each virus causes a distinct syndrome, though they share some symptoms and consequences.

Most people who become infected with hepatitis B get rid of the virus within 6 months. A short infection is known as an "acute" case of hepatitis B.
Approximately 10% of people infected with the hepatitis B virus develop a chronic, life-long infection. People with chronic infection may have symptoms, but many of these patients never develop symptoms. These patients are sometimes referred to as "carriers" and can spread the disease to others. Having chronic hepatitis B increases your chance of permanent liver damage, including cirrhosis (scarring of the liver) and liver cancer.

Causes, incidence, and risk factors

Hepatitis B is transmitted via blood and other body fluids. Infection can occur through:

• Contact with blood in healthcare settings - this puts physicians, nurses, dentists, and other healthcare personnel at risk
  
• Unsafe sex with an infected person
  
• Blood transfusions
  
• Sharing needles during drug use
  
• Receiving a tattoo or acupuncture with contaminated instruments
  
• Birth - an infected mother can transmit the virus to the baby during delivery or shortly thereafter
  

People who are at higher risk, including people who live with someone with hepatitis B and healthcare workers, should get the hepatitis B vaccine.

In acute hepatitis, it takes about 1 to 6 months from the time of infection until the disease manifests itself. Early symptoms may include nausea and vomiting, loss of appetite, fatigue, and muscle and joint aches. Jaundice, together with dark urine and light stools, follows. About 1 percent of patients infected with hepatitis B die due to liver damage in this early stage.

The risk of becoming chronically infected depends on the age at the time of infection. More than 90% of newborns, about 50% of children, and less than 5% of adults infected with hepatitis B develop chronic hepatitis.

Most damage from hepatitis B virus is caused by the body's response to the infection. The body's immune response against the infected liver cells (hepatocytes) damages the cells, causing liver inflammation (hepatitis). As a result, liver enzymes (transaminases) leak out of the liver into the blood, causing transaminase blood levels to be elevated. The virus impairs the liver's ability to produce the clotting factor prothrombin, increasing the time required for blood clot formation (prothrombin time).Liver damage also impairs the body's ability to rid itself of bilirubin (a breakdown product of old red blood cells), causing jaundice (yellow discoloration of the eyes and body) and dark urine.