Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
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
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.
Symptoms of acute viral hepatitis include fatigue,
light-colored stools, fever, and jaundice; however, acute viral hepatitis may occur with minimal symptoms that go unrecognized. Rarely, acute viral hepatitis causes fulminant hepatic failure.
The symptoms of chronic viral hepatitis often are mild and nonspecific, and the diagnosis of chronic hepatitis often is delayed.
Chronic viral hepatitis often requires treatment in order to prevent progressive liver damage, cirrhosis, liver failure, and
Hepatitis infections can be prevented by avoiding exposure to viruses, injectable immunoglobulins or by vaccines; however, there is vaccine 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.
Viral hepatitis definition and overview
Hepatitis means inflammation of the liver. Many illnesses and conditions can cause inflammation of the liver, for example, drugs, alcohol, chemicals, and autoimmune diseases. Many viruses, for example, the virus of 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
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
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,
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.
The CDC divides travel vaccinations into three categories: 1) routine,
2) recommended, and 3) required. The only vaccine classified as "required" by
International Health Regulations is the yellow fever vaccination for travel to
certain countries in sub-Saharan Africa and tropical South America.
"Routine" vaccinations are those that are normally
administered, usually during childhood, in the United States. These include immunizations against: