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Viral Hepatitis: Overview

Hepatitis is an inflammation of the liver that results in diffuse hepatic cell death and may lead to areas of liver necrosis. It can be acute or chronic (lasting > 6 months) and may progress to fulminant liver failure, cirrhosis, and/or hepatocellular carcinoma. The most common causes of hepatitis in the United States are alcohol abuse and viral infection.

Viral hepatitis can be caused by dozens of viral infections, most commonly the hepatitis viruses (especially hepatitis A, hepatitis B, and hepatitis C) and the herpes viruses (cytomegalovirus, Epstein–Barr virus, varicella–zoster virus, herpes simplex virus).

Most cases are subclinical and asymptomatic. In clinically apparent disease, common symptoms include fever, nausea, vomiting, fatigue, jaundice, right–upper–quadrant abdominal tenderness, and dark urine and pale stools. Extrahepatic manifestations may occur, particularly with chronic hepatitis, and include amenorrhea, arthritis, skin rash, vasculitis, thyroiditis, gynecomastia, glomerulonephritis, polyarteritis nodosa, and Sjögren’s syndrome. Complications of chronic hepatitis include cirrhosis, progressive liver failure, and hepatocellular carcinoma.

Hepatitis A is a self–limited cause of acute hepatitis and does not result in a carrier state or chronic disease. Transmission occurs via the fecal–oral route and most commonly results from poor hygienic practices and inadequate sanitation. Disease is usually mild and self–limited, and patients may be asymptomatic. However, fulminant liver failure may occur in patients with underlying liver disease, especially hepatitis C.

Hepatitis B generally causes a mild or subclinical acute hepatitis, but may result in chronic hepatitis or an asymptomatic carrier state. Progression to chronic hepatitis is most common in perinatal infections and young children. Transmission occurs via blood and body fluids (eg, unprotected sex, intravenous drug use, blood transfusions, tattoo and body piercing). Sexual contact is the most common mode of transmission in the United States, whereas perinatal transmission is common in developing countries.

Hepatitis C is the most common cause of chronic hepatitis in the United States and is the most common indication for liver transplantation. Acute hepatitis is usually asymptomatic, but more than 50% of cases will progress to chronic hepatitis. Hepatitis C patients usually do well for 20 to 25 years before developing cirrhosis, which occurs in about 20% to 30% of chronic cases. Although transmission can occur via blood products, this route is much less common since universal blood screening for hepatitis was initiated in 1990. Intravenous drug use in adults and vertical transmission in infants are the most common causes of hepatitis C today. Transmission rate is higher in patients with concomitant HIV.

Hepatitis D is dependent on co–infection with the hepatitis B virus. If hepatitis D is acquired at the same time as hepatitis B, complete recovery can be expected. However, hepatitis D occurring as a superinfection in a hepatitis B patient can cause a syndrome of accelerated hepatitis, with progression to chronic hepatitis within weeks. Transmission occurs via blood and body fluids.

Hepatitis E usually causes a self–limited and mild acute hepatitis. However, the disease may be severe in pregnant women, in whom it may progress to acute onset of liver failure, with mortality as high as 25%. The virus is most commonly spread by fecally contaminated water in endemic areas. No chronic disease state exists for hepatitis E.

 

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Viral Hepatitis: Risk Factors and Diagnosis >>