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, public health experts recommend that Asian-Americans get tested for chronic hepatitis B. This is because most Asian-Americans came from countries with high rates of the disease or their parents did. 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 thirty 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, Irving Millman, invented the vaccine in nineteen sixty-nine. 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 nineties, Baruch Blumberg 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, at the age of eighty-five.

For VOA Special English, I'm Carolyn Presutti.