For the first time, doctors are reporting that they have cured a child of HIV, the virus that causes AIDS.

The landmark finding will help scientists better understand the nature of HIV, doctors say, and could potentially help countless HIV-positive babies in developing countries.

'I'm sort of holding my breath that this child's virus doesn't come back in the future,' says Hannah Gay, an associate professor of pediatrics at the University of Mississippi Medical Center, who treated the child, a 2½-year-old Mississippi girl. 'I'm certainly very hopeful that it will produce studies that will show us a way to cure other babies in the future.'

Experts note that the girl's story is also unique — involving a string of unusual events — and won't immediately lead to a cure for the 34 million people living with HIV worldwide.

The baby contracted HIV at birth, says study co-author Katherine Luzuriaga of the University of Massachusetts Medical School.

The girl's mother tested positive for HIV when she arrived at the hospital to give birth, Gay says. But the mother hadn't had any prenatal care, including anti-HIV therapy. The baby was born too quickly for doctors to begin any therapy before delivery, as well.

Because doctors suspected the baby would be infected, they began administering anti-AIDS therapy the day after birth, Luzuriaga says..