Viral Hepatitis

What is Hepatitis ?

Hepatitis is the inflammation of the liver. Although hepatitis can be the symptom of many illnesses, including autoimmune diseases, it is most often caused by a viral infection. Many illnesses and conditions can cause inflammation of the liver, for example, drugs, alcohol, chemicals, and autoimmune diseases. Many viruses, for example, the virus causing mononucleosis and the cytomegalovirus can inflame the liver. Most viruses, however, do not attack primarily the liver; the liver is just one of several organs that the viruses affect

When most doctors speak of viral hepatitis, they are using the definition that means hepatitis caused by a few specific viruses that primarily attack the liver and are responsible for about half of all human hepatitis.

There are several hepatitis viruses; they have been named types A, B, C, D, E, F (not confirmed), and G. 

As our knowledge of hepatitis viruses grows, it is likely that this alphabetical list will become longer. The most common hepatitis viruses are types A, B, and C. Reference to the hepatitis viruses often occurs in an abbreviated form (for example HAV,HBV, HCV represent hepatitis viruses A, B, and C, respectively). The focus of this article is on these viruses that cause the majority of human viral hepatitis.

What is Acute Fulminant Hepatitis?

Rarely, individuals with acute infections with HAV and HBV develop severe inflammation, and the liver fails (acute fulminant hepatitis). These patients are extremely ill with the symptoms of acute hepatitis already described and the additional problems of confusion or coma (due to the liver's failure to detoxify chemicals), as well as bruising or bleeding (due to a lack of blood clotting factors). In fact, up to 80% of people with acute fulminant hepatitis can die within days to weeks; therefore, it is fortunate that acute fulminant hepatitis is rare. For example, less than 0.5% of adults with acute infection with HBV will develop acute fulminant hepatitis. This is even less common with HCV alone, although it becomes more frequent when both HBV and HCV are present together.

What is Chronic Viral Hepatitis?

Patients infected with HBV and HCV can develop chronic hepatitis. Doctors define chronic hepatitis as hepatitis that lasts longer than 6 months. In chronic hepatitis, the viruses live and multiply in the liver for years or decades. For unknown reasons, these patients' immune systems are unable to eradicate the viruses, and the viruses cause chronic inflammation of the liver. Chronic hepatitis can lead to the development over time of extensive liver scarring (cirrhosis), liver failure, and liver cancer. Liver failure from chronic hepatitis Cinfection is the most common reason for liver transplantation in the U.S. Patients with chronic viral hepatitis can transmit the infection to others with blood or body fluids (for example, sharing needles, sexually, and infrequently by organ donation) as well as infrequently by transmission from mother to newborn.

Viral Hepatitis Facts :

• Many illnesses and conditions can cause inflammation of the liver (hepatitis), but certain viruses cause about half of all hepatitis in people.
• Viruses that primarily attack the liver are called hepatitis viruses. There are several types of hepatitis viruses including types A, B, C, D, E, and possibly G. Types A, B, and C are the most common.
• All hepatitis viruses can cause acute hepatitis.
• Viral hepatitis types B and C can cause chronic hepatitis.
• Hepatitis infections can be prevented by avoiding exposure to viruses, and through injectable immunoglobulins or by vaccines; however, vaccines are available for only hepatitis A and B.
• Those at risk for viral hepatitis B and C include workers in the health care profession, people with multiple sexual partners, intravenous drug abusers, and people with hemophilia. Blood transfusion is a rare cause of viral hepatitis.

Functions of Liver :

Hepatitis viruses replicate (multiply) primarily in the liver cells. This can cause the liver to be unable to perform its functions. The following is a list of major functions of the liver:

• The liver helps purify the blood by changing harmful chemicals into harmless ones. The source of these chemicals can be external, such as medications or alcohol, or internal, such as ammonia or bilirubin. Typically, these harmful chemicals are broken down into smaller chemicals or attached to other chemicals that then are eliminated from the body in the urine or stool.
• The liver produces many important substances, especially proteins that are necessary for good health. For example, it produces albumin, the protein building block of the body, as well as the proteins that cause blood to clot properly.
• The liver stores many sugars, fats and vitamins until they are needed elsewhere in the body.
• The liver builds smaller chemicals into larger, more complicated chemicals that are needed elsewhere in the body. Examples of this type of function are the manufacture of a fat, cholesterol, and the protein bilirubin.

When the liver is inflamed, it does not perform these functions well, which brings about many of the symptoms, signs, and problems associated with any type of hepatitis. Each hepatitis viral type (A-F) has both articles and books describing the details of infection with that specific virus. This article is designed to give the reader an overview of the predominant viruses that causes viral hepatitis, their symptoms, diagnosis, and treatments, and should help the reader choose the subject(s) for more in depth information.