When Hee-Soon Juon asked her physician a few years ago whether she needed to be screened for exposure to the Hepatitis B virus, he told her, "You don't need to be. You're in the U.S.A."

But Hepatitis B is widespread in Asian and sub-Saharan African countries, including Juon's native South Korea, and many immigrants have brought it with them to the United States.

Getting out the word is critical for two reasons: First, there is a vaccine to prevent transmission of the virus. Second, those who have already contracted it should seek early treatment to prevent potentially deadly consequences.

Worldwide, according to the Hepatitis B Foundation, about two billion people have been infected with the virus, which remains the leading cause of liver cancer. Though it's not common among people born in this country, it actually was first identified by a scientist at Fox Chase Cancer Center in Philadelphia.

Juon is a nurse with a doctorate in public health, so she knew more than most about the virus. Despite her doctor's attitude, she requested the blood test anyway. Learning she wasn't carrying the virus, she got the vaccine.

Had she been harboring the disease, she would have missed the chance to get early, cancer-preventing treatment.

"I said, 'My God, this is really a problem,' " she recalled in an interview in her office at Thomas Jefferson University, where she is now a professor of medical oncology in the Division of Population Science.

Until her own experience, she had been only vaguely aware of the issue. Now, she has broadened her areas of research interest from breast cancer to include liver cancer associated with Hepatitis B virus (HBV) infection.

With funds from the National Institutes of Health, she developed a program in several languages to increase awareness of HBV infection among Asian Americans and to promote screening and vaccination.

"It's under-prioritized in the United States," said Chari Cohen, director of public health for the Hepatitis B Foundation, in Doylestown. "It's a silent disease. It affects people who are marginalized."

Cohen and other advocates see several barriers to fighting HBV:

Lack of funding compared with such diseases as HIV and Hepatitis C that affect the native-born population.

Less awareness in the medical community.

Immigrants' lack of insurance and distrust of the medical system.

Stigma, including unfounded fears that HBV can be spread by casual contact.

"Some people think you can get it if you share chopsticks," said Shumengui Zhai, a research associate and outreach worker at the Center for Asian Health at Temple University.

Skipping the follow-up

Grace Ma, the center director, has estimated that fewer than half the Asian American patients diagnosed with the virus come in for needed follow-up.

Cohen said some people still believe HBV is an inherited disease. In truth, it is spread mainly through unprotected sex; blood-to-blood exposure, including sharing of needles through drug use or tattooing; or from an infected mother to her unborn child.

The African immigrant community also doesn't pay enough attention to the virus, said Amy Jessop, the director of HepTREC, a center for viral hepatitis research and community engagement.

"It's way down in the list in importance," said the associate professor of health policy and public health at the University of the Sciences. "They need to eat. They need to pay rent. They're escaping areas where there's been a lot of violence."

Eyob Feyssa, director of the Hepatitis Treatment and Study Center at Einstein Medical Center, notes that prevalence of Hepatitis B is about 8 percent in some African countries.

But many U.S. practitioners don't realize that they should screen immigrants from such countries. Others are vaccinating patients without screening them first - a useless measure if they already have the virus.

Unlike Hepatitis C, Hepatitis B is not curable, but it can be controlled by medication. Otherwise, one in four patients will develop liver cancer, which is usually fatal.

"By the time symptoms manifest," Cohen said, "it's usually too late."

Around for centuries

Hepatitis B has been around for centuries, but it was first identified scientifically in 1967 by Baruch Blumberg, a researcher at Fox Chase Cancer Center in Philadelphia.

Blumberg received the Nobel Prize for medicine in 1976, after helping develop the vaccine.

Blumberg likely "prevented more cancer deaths than any person who's ever lived," said Jonathan Chernoff, Fox Chase's scientific director, when the laureate died in 2011.

It's an especially dangerous virus in children who catch it from their mothers. Unlike adults, many of whom have strong enough immune systems to fight off the virus, children lack such defenses.

But babies who are quickly treated after delivery will avoid the disease about 95 percent of the time.

It could take two generations

Pediatrician Philip Siu, clinical director of Chinatown Medical Services, says Hepatitis B could be eradicated within two generations. The National Academies of Sciences, Engineering, and Medicine, in a report last month, agreed with that estimate.

Why the optimism? Siu credits growing awareness in the medical community, and the work of advocates such as the Hepatitis B Foundation, the African Family Health Organization in West Philadelphia, and Hep B United Philadelphia.

The Center for Asian Health also provides navigators such as Zhai, a native of China, to accompany patients on their medical visits, especially if they don't speak English.

The Philadelphia Department of Health has CDC grants to step up surveillance, particularly among pregnant women. Helping that effort are new guidelines from the American College of Obstetricians and Gynecologists, requiring that pregnant women be tested for HBV.

There are about 20,000 HBV carriers in the city, estimates Kendra Viner, a program manager at the department. That compares with 50,000 carrying Hepatitis C.

The next step, Cohen said, would be for Hepatitis B testing to be made standard for everyone universal by including it in the Quality Measures of the Centers for Medicare and Medicaid Services (CMS).

But even if the disease can be eliminated in a few decades, millions of people need help now. More than 50 scientists funded by the Hepatitis B Foundation are among those seeking a cure, Cohen said.

"It's a long, difficult process."