Liz Szabo, USA TODAY6:38p.m.March 4, 2013

Doctors are thrilled with the cure of a 2½-year-girl infected with HIV at birth but say that extending that success to others will be a challenge.

More than 300,000 babies a year worldwide are born infected with HIV, the virus that causes AIDS.

As of this week, doctors appear to have cured exactly one.

And while the Mississippi child’s story has generated excitement in the medical community, researchers also note that it will likely take years before they’re able to extend that success to a broader community of patients, if ever.

“This is a really groundbreaking report,” says Diane Havlir, a professor and AIDS researcher at the University of California-San Francisco, who attended a presentation of the new study Monday at an Atlanta medical conference.

“This tells us a cure is possible,” says Havlir, who wasn’t involved in the new study, which reported on a 2½-year-old girl who was infected with HIV at birth but apparently cured after 18 months of triple-drug therapy. “That is thrilling news.”

Doctors credit the child’s cure to early treatment; her physicians began treatment soon after delivery, which is the standard of care for the child of an untreated, HIV-positive mother.

STORY: Doctors report first cure of HIV in a child

Most adults can’t benefit from such early therapy, because they typically don’t even learn that they’re infected for months or years, says Rana Chakraborty, an associate professor of pediatrics at Emory University School of Medicine. The only adult to have been definitively cured of HIV had a unique situation: He had a bone-marrow transplant to treat his leukemia from a donor with a genetic mutation that provided protection from HIV.

Scientists will first have to learn what exactly allowed the child to be cured before they can apply that knowledge to developing vaccines or new drugs, he says.

And Havlir notes that doctors are unlikely to make any changes to children’s care before they can verify the study’s results. She notes that, in developed countries, doctors focus far more on prevention than treatment. Giving women anti-HIV therapy while pregnant reduces the risk of mother-to-child transmission by 98%.

But if the results hold up and doctors can identify the best medications, they could start anti-AIDS therapy on high-risk newborns even before getting results of their HIV tests, Havlir says.

That could be important in developing countries, where many women — like the mother of this Mississippi child — don’t get recommended care. The girl’s mother had no prenatal care, let alone anti-HIV therapy, before delivery. Then, when the girl was 18 months old, the mother stopped bringing her to the doctor, which left the child with no anti-HIV treatment for five months.

While the child’s story has been hailed as a victory for science, Chakraborty says the case also illustrates the single greatest challenge in treating AIDS: actually getting care to patients.

Delivering on the promise of scientific breakthroughs has been a challenge not just in developing countries of Africa, but in the USA.

Only 28% of people of the 1.2 million HIV-positive Americans have been diagnosed and treated successfully so that their levels of virus are undetectable, according to the Centers for Disease Control and Prevention.

HIV has become entrenched among the poor in the USA. Many patients lack access to health care and grapple with other problems that keep them from getting the care they need, such as homelessness, drug addiction or mental illness, Chakraborty says.

“Many individuals fall out of care, especially in adolescence or young adulthood,” Chakraborty says. “Young people think they’re invincible.”

Yet Havlir says scientists are ready to confront such obstacles.

“There are daunting challenges,” Havlir says, “but they are challenges that the field is going to embrace, because many people think they are surmountable.”