hepatitis hĕpˌətīˈtĭs [key], inflammation of the liver. There are many types of hepatitis. Causes include viruses, toxic chemicals, alcohol consumption, parasites and bacteria, and certain drugs. Symptoms of hepatitis are nausea, fever, weakness, loss of appetite, sudden distaste for tobacco smoking, and jaundice.

A number of viruses can cause acute viral hepatitis. Five have been identified and named hepatitis A through E. At least 10 other viruses are under study. Hepatitis A, also called infectious hepatitis, occurs sporadically or in epidemics, the virus being present in feces and transmittable via contaminated food (e.g., food prepared by an infected person with unwashed hands or fresh food washed or grown with contaminated water) or water. A person with active infection can spread it by physical contact. The disease usually resolves on its own. Exposed persons can be protected by injections of gamma globulin. A vaccine was made available in 1995 and is recommended for children at risk for the virus.

Hepatitis B, also called serum hepatitis, was commonly transmitted through blood transfusions until the 1970s, when screening tests were introduced. Intravenous-drug abusers remain a high-risk group because of the sharing of needles. It is also spread by sexual transmission and from mother to baby at birth. Some infected individuals, particularly children, become chronic carriers of the virus. Hepatitis B can progress to chronic liver disease and is associated with an increased risk of developing liver cancer. A vaccine, available since 1981, is recommended for all infants and others at risk for the virus. Alpha-interferon was approved as a treatment in 1992.

Hepatitis C, formerly called non-A, non-B hepatitis, is also transmitted by contaminated blood transfusions and by sharing of needles among drug abusers, although in many cases no source can be identified. It is the most common form of chronic liver disease in the United States. Many of those infected have no symptoms but become carriers. The virus can cause serious liver damage and is the leading cause of liver transplants in the United States. Blood banks routinely screen for hepatitis C. Depending on the genetic makeup of the virus, antivirals, either alone or in conjunction with alpha-interferon and the drug ribavirin, are used to treat the disease, and may result in a long-term cure.

Hepatitis D, or delta hepatitis, affects only people with hepatitis B; those infected with both viruses tend to have more severe symptoms. Hepatitis E is spread by consuming feces-contaminated food or water. It is common in Mexico, Africa, and Asia and is especially serious in pregnant women.

Hepatitis can be incurred as a complication of several other disorders in addition to viral infection, among them amebic dysentery, cirrhosis of the liver, and mononucleosis. Also, alcohol, carbon tetrachloride, some tranquilizers and antibiotics, and many other substances can produce a toxic reaction in the liver, resulting in toxic hepatitis.

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