This is the VOA Special English Health Report.

Today we answer a question. Vu Quang Hien from Vietnam wants to know more about hepatitis B. Hepatitis is the name for a group of viral infections that attack the liver. These are called A, B, C and so on.

An estimated two billion people are infected with hepatitis B. The rates are highest in China and other parts of Asia. The World Health Organization says most of these infections happen during childhood.

Hepatitis B is spread through contact with infected blood or other body fluids. Mothers can infect babies at birth. Unsafe injections and sexual contact can also spread the virus. Experts say it can survive outside the body for at least a week.

There are two forms of hepatitis B -- acute and chronic. Acute cases last for several weeks, although recovery can take months. Chronic cases can lead to death from cirrhosis or scarring of the liver and liver cancer.

Yet people with long-term liver infections can live for years and not even know they are infected. The ones most likely to develop chronic hepatitis B are young children.

In the United States, experts at the Centers for Disease Control and Prevention urge medical providers to test Asian-American patients.

DR. JOHN WARD: "The bottom line -- since most people of Asian heritage came to the US from endemic countries or were born to parents from these countries, they should be screened for chronic hepatitis B."

For acute hepatitis B, patients may receive care to replace lost fluids, but there are no treatments. Doctors can treat chronic cases with interferon and antiviral drugs. But these medicines cost too much for most of the world's poor.

A vaccine to prevent hepatitis B has been available for 30 years. The researcher who discovered this vaccine -- and hepatitis B itself -- was an American named Baruch Blumberg. Dr. Blumberg also showed that the virus could cause liver cancer.

He and another researcher at the Fox Chase Cancer Center in Philadelphia, Irving Millman, invented the vaccine in 1969. But Dr. Blumberg said it took some time to find a drug company willing to produce it.

He first became interested in studying infectious disease when he volunteered in Surinam during his medical training.

His discoveries with hepatitis B saved many lives and earned him a Nobel Prize in medicine. But he also had other interests -- including the search for life in outer space.

In the late 1990s, he helped launch the Astrobiology Institute at NASA. He was at a space agency conference in California in April when he died, apparently of a heart attack. Baruch Blumberg was 85 years old.

And that's the VOA Special English Health Report, written by Caty Weaver. I'm Steve Ember.

cirrhosis: a serious disease of the liver, caused especially by drinking too much alcohol 肝硬化；肝硬变

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（来源：VOA 编辑：崔旭燕）