Viral hepatitis is an inflammation of the liver caused by a virus. The liver, the largest internal organ in the body, is responsible for more than 500 functions. When the liver swells from the infection, it cannot effectively complete its essential tasks, which include:

• Digestion. The liver produces bile, the greenish fluid stored in the gallbladder that helps digest fats.
  
  
• Energy storage. The liver processes most of the nutrients absorbed in the intestine.
  
  
• Removal of poisons. The liver metabolizes or breaks down and eliminates drugs, alcohol and other harmful substances from the blood.
  
  
• Production of other important chemicals. The liver produces cholesterol, vitamin A, blood-clotting factors and certain proteins.
  

  

There are five basic types of viral hepatitis: A, B, C, D and E. The virus is transmitted in a number of different ways, depending on the form of hepatitis. In most cases, hepatitis is the result of contact with bodily fluids from an infected person during sexual intercourse, shared use of needles or exposure to blood. However, hepatitis A and E are also transmitted through consuming food or water contaminated with feces from an infected person. Some studies have shown that, unlike many other viral infections, the damaged caused by viral hepatitis may be due to the immune response to the virus, rather than the virus itself.

People who contract viral hepatitis may experience it in two forms:

• Acute viral hepatitis. Initially, all forms of viral hepatitis are experienced as short-term viral infection. In many cases, this form of hepatitis will resolve on its own without the need for treatment, and in some cases the patient may not experience symptoms or even be aware of the infection.
  
  
• Chronic viral hepatitis. In some cases, acute viral hepatitis will develop into this longer-lasting viral infection that is present for at least six months and often for a lifetime. Hepatitis B and C can develop into chronic viral hepatitis. In some cases, patients can be unaware of these infections for decades before they start to cause serious illness.

Chronic viral hepatitis can lead to cirrhosis of the liver, in which liver cells die and are replaced by scar tissue and fat. In addition, patients may go on to develop liver failure or liver cancer. There is no cure for this form of viral hepatitis, although treatments can help keep the virus at bay and prevent further damage to the liver. In some cases, patients require liver transplants.

Most forms of viral hepatitis cannot be transmitted through casual contact, such as hugging or shaking hands. However, it is possible for people to contract hepatitis A by touching their mouth after touching an infected person (e.g., after shaking hands).