In the United States, drug therapy has tamed the most vicious effects of AIDS for many people, letting them live relatively long and healthy lives.

But in many countries around the world, and particularly in parts of sub-Saharan Africa, the disease continues to sweep away whole families, even whole villages, and leave millions of orphans behind.

Millions of other African children -- lacking the two doses of antiretroviral drugs that could protect them from the virus, and that almost all American children of HIV/AIDS patients now receive -- contract the disease from their mothers during labor or breast-feeding. About half of those children die before their second birthdays.

Even in the United States, HIV/AIDS remains a common disease, said Talia Rosenberg, a 24-year-old Squirrel Hill resident who will walk 35 miles across Swaziland from June 30 to July 5 to draw attention to pediatric AIDS.

"It's not something that's gone away, even though it seems like it's just in Africa," she said. "There are plenty of populations still in the United States who have the disease."

Ms. Rosenberg, a 2002 graduate of Allderdice High School who graduated from Harvard University with a degree in applied math and plans to attend Yale School of Medicine this fall, will serve as youth ambassador for the Elizabeth Glaser Pediatric AIDS Foundation during the walk. Ms. Rosenberg, the group's first youth representative, won an essay contest about how young people can make a difference in the fight against pediatric HIV/AIDS.

During the walk, Ms. Rosenberg and scores of other people raising money for the foundation's research will visit clinics, orphanages and hospitals to meet scientists, medical workers and families who are fighting HIV/AIDS. It is hoped, she said, the foundation's representatives can convey the message that the rest of the world has not forgotten about their struggles.

"It's probably very important for people working with the disease and fighting the disease to know they're not alone," she said. "They should know that people still care."

Ms. Rosenberg also will file a blog and shoot pictures and videos for the foundation's Web site during her trip, allowing people to follow her journey in real time.

People who are walking with Ms. Rosenberg have each raised at least $15,000 to support the foundation's research, advocacy, and prevention and treatment programs, and to raise awareness about pediatric HIV/AIDS.

Globally, an estimated 33.2 million people live with HIV/AIDS, of whom 2.5 million are children, according to the foundation. More than two-thirds of all those infected people -- and about 90 percent of the world's HIV-infected children-- live in sub-Saharan Africa. The region sees about three-quarters of the world's AIDS deaths.

In Swaziland, nearly 40 percent of the population is infected with HIV/AIDS, and nearly all of the new HIV infections among young children come from the mother during pregnancy or breast-feeding.

In 2007, about one-third of HIV-positive pregnant women around the world received the antiretroviral medicines that can prevent the transmission of HIV to their babies, according to information gathered by the United Nations. And despite progress, more than 1,000 children under the age of 15 still contract HIV each day, according to the foundation.

Someday, researchers might achieve a breakthrough and produce a vaccine that can eliminate or at least control the spread of HIV/AIDS, much as has been done with smallpox or polio, Ms. Rosenberg said. But that vaccine, she said, almost certainly is a long way off, and it will require money, effort and commitment to achieve.

Then there's the added effort of ensuring that the vaccine is affordable and available to people in the developing world.

"I would implore anyone who reads this to see what you can do, how you can help," said Ms. Rosenberg, who until recently worked as a research technician at New York's Aaron Diamond AIDS Research Center. "Even though it's far away with people who aren't exactly like you, it's tremendously important to work and to help."

For more information about the walk, go to www.pedaids.org/awa2008.