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, and the virus may eventually cause liver damage. Blood banks routinely screen for hepatitis C. Alpha-interferon is used also to treat hepatitis C, in combination with the drug ribavirin, 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.
Inflammation of the liver. There are seven known types of viral hepatitis (A-G). Types A, spread mainly through food contaminated with feces, and B, transmitted sexually or by injection, cause jaundice and flulike symptoms. The hepatitis C virus spreads mostly by shared needles in intravenous drug use and can cause liver cirrhosis and cancer after a long latent period. Until recently there was no test to detect it in blood, and many people were exposed through blood transfusions. Hepatitis D becomes active only in the presence of type B; it causes severe chronic liver disease. Type E, like Type A, is transmitted by contaminated food or water; its symptoms are more severe than Type A's and can result in death. The hepatitis F virus (HFV), which was first reported in 1994, is spread like Type A and E. The hepatitis G virus (HGV), isolated in 1996, is believed to be responsible for many sexually transmitted and bloodborne cases of hepatitis. Vaccines exist for types A and B (the second also prevents type D). Drug treatment for B and C is not always effective. The other types may not need drug treatment. Chronic active hepatitis causes spidery and striated skin markings, acne, and abnormal hair growth. It results in liver tissue death (necrosis) progressing to cirrhosis. Alcoholic hepatitis, from long-term overconsumption of alcohol, can be reversed and cirrhosis prevented by early treatment including quitting or sharply reducing drinking. Other drugs can also cause noninfectious hepatitis. An autoimmune hepatitis affects mainly young women and is treated with corticosteroids to relieve symptoms.
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Hepatitis (plural hepatitides) implies injury to the liver characterized by the presence of inflammatory cells in the tissue of the organ. The name is from ancient Greek hepar (ηπαρ) or hepato- (ηπατο-), meaning liver, and suffix -itis, meaning "inflammation" (c. 1727). The condition can be self-limiting, healing on its own, or can progress to scarring of the liver. Hepatitis is acute when it lasts less than six months and chronic when it persists longer. A group of viruses known as the hepatitis viruses cause most cases of liver damage worldwide. Hepatitis can also be due to toxins (notably alcohol), other infections or from autoimmune process. It may run a subclinical course when the affected person may not feel ill. The patient becomes unwell and symptomatic when the disease impairs liver functions that include, among other things, removal of harmful substances, regulation of blood composition, and production of bile to help digestion.
Clinically, the course of acute hepatitis varies widely from mild symptoms requiring no treatment to fulminant hepatic failure needing liver transplantation. Acute viral hepatitis is more likely to be asymptomatic in younger people. Symptomatic individuals may present after convalescent stage of 7 to 10 days, with the total illness lasting 2 to 6 weeks.
Initial features are of nonspecific flu-like symptoms, common to almost all acute viral infections and may include malaise, muscle and joint aches, fever, nausea or vomiting, diarrhea, and headache. More specific symptoms, which can be present in acute hepatitis from any cause, are: profound loss of appetite, aversion to smoking among smokers, dark urine, yellowing of the eyes and skin (i.e., jaundice) and abdominal discomfort. Physical findings are usually minimal, apart from jaundice (33%) and tender hepatomegaly (10%). There can be occasional lymphadenopathy (5%) or splenomegaly (5%).
Majority of patients will remain asymptomatic or mildly symptomatic, abnormal blood tests being the only manifestation. Features may be related to the extent of liver damage or the cause of hepatitis. Many experience return of symptoms related to acute hepatitis. Jaundice can be a late feature and may indicate extensive damage. Other features include abdominal fullness from enlarged liver or spleen, low grade fever and fluid retention (ascites). Extensive damage and scarring of liver (i.e., cirrhosis) leads to weight loss, easy bruising and bleeding tendencies. Acne, abnormal menstruation, lung scarring, inflammation of the thyroid gland and kidneys may be present in women with autoimmune hepatitis.
Most cases of acute hepatitis are due to viral infections:
Ethanol, mostly in alcoholic beverages, is a significant cause of hepatitis. Usually alcoholic hepatitis comes after a period of increased alcohol consumption. Alcoholic hepatitis is characterized by a variable constellation of symptoms, which may include feeling unwell, enlargement of the liver, development of fluid in the abdomen ascites, and modest elevation of liver blood tests. Alcoholic hepatitis can vary from mild with only liver test elevation to severe liver inflammation with development of jaundice, prolonged prothrombin time, and liver failure. Severe cases are characterized by either obtundation (dulled consciousness) or the combination of elevated bilirubin levels and prolonged prothrombin time; the mortality rate in both categories is 50% within 30 days of onset.
Alcoholic hepatitis is distinct from cirrhosis caused by long term alcohol consumption. Alcoholic hepatitis can occur in patients with chronic alcoholic liver disease and alcoholic cirrhosis. Alcoholic hepatitis by itself does not lead to cirrhosis, but cirrhosis is more common in patients with long term alcohol consumption. Patients who drink alcohol to excess are also more often than others found to have hepatitis C. The combination of hepatitis C and alcohol consumption accelerates the development of cirrhosis.
A large number of drugs can cause hepatitis:
The clinical course of drug-induced hepatitis is quite variable, depending on the drug and the patient's tendency to react to the drug. For example, halothane hepatitis can range from mild to fatal as can INH-induced hepatitis. Hormonal contraception can cause structural changes in the liver. Amiodarone hepatitis can be untreatable since the long half life of the drug (up to 60 days) means that there is no effective way to stop exposure to the drug. Statins can cause elevations of liver function blood tests normally without indicating an underlying hepatitis. Lastly, human variability is such that any drug can be a cause of hepatitis.
The diagnosis depends on medical history, physical exam, blood tests, radiological imaging and sometimes a liver biopsy. The initial evaluation to identify the presence of fatty infiltration of the liver is medical imaging, including such ultrasound, computed tomography (CT), or magnetic resonance (MRI). However, imaging cannot readily identify inflammation in the liver. Therefore, the differentiation between steatosis and NASH often requires a liver biopsy. It can also be difficult to distinguish NASH from alcoholic hepatitis when the patient has a history of alcohol consumption. Sometimes in such cases a trial of abstinence from alcohol along with follow-up blood tests and a repeated liver biopsy are required.
NASH is becoming recognized as the most important cause of liver disease second only to hepatitis C in numbers of patients going on to cirrhosis.
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