NEW YORK — Doctors announced Sunday that a baby had been cured of an HIV infection for the first time, a startling development that could lead to more aggressive treatment of babies infected at birth and a sharp reduction in the number of children living with the virus that causes AIDS.
The baby, born in rural Mississippi, was treated with antiretroviral drugs starting around 30 hours after birth, something that is not usually done. If further study shows this works in other babies, it will almost certainly change the way newborns of infected mothers are treated all over the world.
The case was investigated by researchers at the Johns Hopkins Children’s Center and the University of Massachusetts Medical Center. Their findings will be reported Monday at the Conference on Retroviruses and Opportunistic Infections in Atlanta.
The United Nations estimates that 330,000 babies were newly infected in 2011, the most recent year for which there is data, and that more than 3 million children globally are living with HIV.
If the report is confirmed, the child born in Mississippi would be only the second well-documented case of a cure in the world, giving a boost to research aimed at a cure, something that only a few years ago was thought to be virtually impossible.
The first person cured was Timothy Brown, known as the ‘‘Berlin patient,’’ a middle-aged man with leukemia who received a bone-marrow transplant from a donor genetically resistant to HIV infection.
‘‘For pediatrics, this is our Timothy Brown,’’ said Dr. Deborah Persaud, associate professor at the Johns Hopkins Children’s Center and lead author of the report on the baby. ‘‘It’s proof of principle that we can cure HIV infection if we can replicate this case.’’
Persaud and other researchers spoke in advance of a presentation of the findings on Monday at the Conference on Retroviruses and Opportunistic Infections in Atlanta.
Some outside experts, who have not yet heard all the details, said they needed convincing that the baby had truly been infected. If not, this would be a case of prevention, something already done for babies born to infected mothers.
“The one uncertainty is really definitive evidence that the child was indeed infected,’’ said Dr. Daniel R. Kuritzkes, chief of infectious diseases at Brigham and Women’s Hospital.
Persaud and some other outside scientists said they were certain the baby — whose name and gender were not disclosed — had been infected. There were five positive tests in the baby’s first month of life — four for viral RNA and one for DNA. And once the treatment started, the virus levels in the baby’s blood declined in the pattern characteristic of infected patients.
Persaud said there was also little doubt that the child experienced what she called a ‘‘functional cure.’’ Now 2½, the child has been off drugs for a year with no sign of functioning virus.
The mother arrived at a rural hospital in the fall of 2010 already in labor and gave birth prematurely. She had not seen a doctor during the pregnancy and did not know she had HIV. When a test showed the mother might be infected, the hospital transferred the baby to the University of Mississippi Medical Center, where it arrived at about 30 hours old.
Dr. Hannah B. Gay, an associate professor of pediatrics, ordered two blood draws an hour apart to test for the presence of HIV RNA and DNA.
The tests found a level of virus at about 20,000 milliliters, fairly low for a baby. But since tests so early in life were positive, it suggests that the infection occurred in the womb rather than during delivery, Gay said.
Typically a newborn with an infected mother would be given one or two drugs as a prophylactic measure. But Gay said that based on her own experience, she almost immediately used a three-drug regimen aimed at treatment, not prophylaxis, not even waiting for the test results confirming infection.
Virus levels rapidly declined with treatment and were undetectable by the time the baby was a month old. That remained the case until the baby was 18 months old, after which the mother stopped coming to the hospital.
When the mother and child returned five months later, Gay expected to see high viral loads in the baby. But the tests were negative.
Suspecting a laboratory error, she ordered more tests. ‘‘To my greater surprise, all of these came back negative,’’ Gay said.