Liz Szabo, USA TODAY
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.
The baby's case was exceptional from the beginning.
It's rare today for babies to be born with HIV, says Anthony Fauci, a director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, which partly funded the study.
Doctors now routinely treat HIV-positive pregnant women with anti-retroviral medications and give preventive treatment to babies for the first six weeks of life, Luzuriaga says.
This regimen has reduced mother-to-child transmission from 25% to 30% - in the days before anti-retroviral therapy - to less than 2% today, Gay says.
Normally, doctors would keep an HIV-positive baby like this on medications for the rest of her life, for fear that the virus would come raging back, Gay says.
In another unusual twist, however, the girl and mother disappeared when she was about 18 months old, Gay says. They missed several appointments, leading doctors to seek help from social services to track them down.
The mother and toddler finally returned to the hospital five months later, having taken no anti-AIDS medication during that time, says Gay, whose study was presented Sunday at the 2013 Conference on Retroviruses and Opportunistic Infections in Atlanta.
While most HIV-positive mothers do their best to give children recommended medications, a small number drop out of care, Gay says. "It's more common than we would like," she says, noting that many of those infected with HIV suffer from poverty, homelessness and other problems that can interfere with care.
Doctors fully expected to find high levels of HIV, Gay says.
They were surprised to learn that the child appeared HIV-free, with virus levels "undetectable," according to the new study, co-led by researchers at Johns Hopkins' Children Center in Baltimore.
Today, 10 months after stopping drug therapy, the child remains free of HIV, Luzuriaga says.
"That's a miracle," says Carlos del Rio, co-director of the Emory Center for AIDS Research and a board member at HIVMA (the HIV Medicine Association), who wasn't involved in the study. "This kid could have died from the HIV infection. This outcome is the exception, rather than the rule."
Del Rio says the child's cure shouldn't lead patients or parents to think they can stop medication.
The study's authors say they don't yet have enough evidence to recommend changing children's care. First, they need to find out if this child's cure was a one-of-a-kind miracle, or something that doctors can achieve in other babies.
The Mississippi child's case likely will have a greater practical impact in developing countries, rather than the USA, Fauci says.
That's because most women here get prenatal care and anti-AIDS therapy before delivery, so very few babies today are born with HIV anymore, Fauci says.
In developing nations, however, some mothers get no prenatal care. The new study suggests that providing AIDS drugs soon after birth could protect these babies, Fauci says.
"It's only one case," Fauci notes. "It's a pretty convincing case. But you always have to be careful not to make too much of one case."
Gay says doctors don't know for sure why the child was cured.
It's possible that giving anti-retroviral drugs so early prevented the AIDS virus from hiding in her white blood cells, which can serve as "reservoirs" of infection. These reservoirs of hidden cells can cause the disease to come back if patients stop their medications.
"They have done a lot of tests to see if there is something different about this child's immune system or to see if there is something different about the virus itself," Gay says. "Her virus doesn't seem to be any less virulent. We haven't found anything about the host, this child, or in the mother."
Fauci says the child's cure lends support to something scientists have long believed: that a cure is possible "if you can get somebody treated before the reservoir of virus forms in the body, and before the immune system has been damaged by months or years of viral replication."
Health care workers accidentally exposed to HIV, for example, receive preventive therapy, which is invariably effective, Fauci says.
Most adults, however, are infected for many months or years before even being diagnosed, Fauci says.
Only about three adults have ever been cured of HIV, Fauci says. But their cases are so rare that doctors can't use the same techniques to cure others.
The first man cured of HIV, Timothy Brown of San Francisco, also was diagnosed with leukemia. In 2006, he received a bone-marrow transplant while living in Berlin. That's a harrowing procedure in which doctors eradicate a patient's own immune system, then repopulate it with immune cells from a donor.
In Brown's case, the donor carried a genetic mutation that protects people from HIV. He was able to stop anti-AIDS therapy and remains disease-free.
Two other patients in Boston also appear to have been cured, Fauci says.
Doctors would never put the millions of people currently infected with HIV through such a grueling and expensive therapy, which can cost upward of $100,000 per patient.
The Mississippi child's case "underscores the importance of identifying HIV-positive pregnant women," says Rowena Johnston, vice president and director of research at amfAR, the Foundation for AIDS Research, which helped fund the study. It's just as critical to expand access to treatment for pregnant women, and to put infants immediately on medications, she says.
"It is also imperative that we learn more about a newborn's immune system, how it differs from an adult's, and what factors made it possible for the child to be cured," Johnston said in a statement.
In the early days of AIDS, doctors sometimes reported seeing infected babies who appeared to spontaneously clear the infection on their own. Those reports all came before doctors had access to new, incredibly sensitive tests, which can detect very small levels of virus, suggesting the cases may have been misdiagnoses, Gay says.
Doctors say they hope to make the most of this rare chance.
"Every rare case should be looked at as an opportunity to learn something," Del Rio says.