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What Causes Hepatitis? continued...

About 400 million people worldwide, including 800,000 to 1.4 million people in the United States, are chronic carriers of this virus. Worldwide, about 1 million people die annually from hepatitis B. Hepatitis B is the most common cause of cirrhosis and liver cancer worldwide.

Hepatitis Cis usually spread through contact with blood or contaminated needles, including tattoo needles. 3.2 million people in the US are chronically infected. Although hepatitis C may cause only mild symptoms or none at all, about 20% to 30% of those infected develop cirrhosis, liver cancer, or both within 20 to 30 years. The disease can be passed on through blood transfusions, but screening, which started in 1992, has greatly reduced the number of such cases. As opposed to hepatitis B, hepatitis C is only infrequently spread through sex.

Hepatitis D happens only in people infected with hepatitis B and tends to make that disease more severe. It can be spread from mother to child and through sex. Although less common, hepatitis D is especially dangerous, because it involves two viruses working at once.

Hepatitis E happens mainly in Asia, Mexico, India, and Africa; only a few cases are reported in the United States, mostly in people who have returned from a country where the disease is widespread. Like hepatitis A, this type is usually spread through fecal contamination, and it does not lead to chronic hepatitis. This form is considered slightly more dangerous than hepatitis A. It can cause severe disease and death in pregnant women.

Other viruses. Other viruses may also cause hepatitis. These include the Epstein-Barr virus (often associated with mononucleosis), the varicella virus (which causes chickenpox), the herpes simplex virus (HSV), and cytomegalovirus ( CMV).

Although viruses are the most common cause of hepatitis, other causes include autoimmune liver disease, obesity, alcohol, toxins, or misuse of certain prescription drugs and over-the-counter drugs such as Tylenol. These forms of hepatitis can cause the same symptoms and liver inflammation that result from viral hepatitis, but are not contagious.

What Puts You at Risk?

See how viral hepatitis spreads. Discover where the risk is greatest.
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