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Scientists believe a little girl who was born with HIV has been cured of the infection. She is the first child and only the second person in the world known to have been cured since the virus touched off a global pandemic more than 30 years ago.
NPR's Richard Knox says the case has major implications for hundreds of thousands of children around the world who get infected with HIV at birth every year.
RICHARD KNOX, BYLINE: Doctors aren't releasing the child's name, but we know she was born in Mississippi and is now two-and-a-half years old and healthy. Doctors say she got HIV before birth from her mother. It's rare for children to be born with HIV in the United States these days. There were fewer than 130 last year. That's because most HIV-infected pregnant women get antiviral drugs that prevent their babies from being infected.
The Mississippi child's surprising cure came about from happenstance and the quick thinking of a University of Mississippi pediatric specialist named Hannah Gay.
HANNAH GAY: The child came to our attention as a high-risk exposure to maternal HIV.
KNOX: High-risk because her mother hadn't had any prenatal care, so she didn't get antiviral drugs during pregnancy. So Dr. Gay decided to begin treating the child immediately, within 31 hours of birth. That's quicker than most infants born with HIV get treated. And she gave higher-than-usual doses of three powerful HIV drugs.
Over the months, standard tests could detect no virus in her blood. That's normal. Then her mother stopped coming in for checkups.
GAY: I saw her at 18 months, and then after that, did not see her for several months, and we were unable to locate her for a while.
KNOX: When they tracked her down, the mother said she'd stopped giving antiviral drugs six or seven months earlier. Dr. Gay expected to find HIV in the child's blood. But to her astonishment, tests couldn't find any virus.
GAY: My first thought was: Oh, my goodness. I've been treating a child who's not actually infected.
KNOX: A look at the earlier blood work confirmed that she had been infected with HIV at birth. So Gay then thought the lab must have made a mistake with the new blood samples. She ran the tests again.
GAY: When all of those came back negative, I knew that something odd was afoot.
KNOX: That was last August. Since then, researchers at labs all over the country have run ultra-sensitive tests on the baby's blood. A couple of tests have found pieces of the virus, but no evidence that HIV is replicating in the child's cells.
Dr. Katherine Luzuriaga of the University of Massachusetts says this amounts to what's called a functional cure.
KATHERINE LUZURIAGA: Which means control of viral replication and lack of rebound once they come off anti-retroviral medications.
KNOX: The only other such case known to AIDS researchers is the so-called Berlin patient - a man named Timothy Brown. But his treatment involved a bone marrow transplant from a donor who's genetically resistant to HIV. That's not something that can be easily duplicated.
By contrast, the Mississippi child's cure involved readily available medicines. Luzuriaga says the toddler's cure has electrified researchers searching for a cure.
LUZURIAGA: It has.
LUZURIAGA: It has. And we just want to see if we can replicate this. Because if we were able to replicate this, I think this would be very good news for our children and their families.
KNOX: Details of the case were presented yesterday at a scientific conference by Dr. Deborah Persaud of Johns Hopkins University.
DEBORAH PERSAUD: This is definitely a game-changer. And so this case was sort of the inspiration and provides the rationale to really move forward.
KNOX: Plans are under way to mount studies to see if early, aggressive treatment can cure other children of HIV. But Persaud says it will be a while before researchers can figure out when it might be safe to deliberately stop antiviral drugs.
This research will be high-priority. While mother-to-child infections are uncommon in the United States, there are almost a thousand a day in the developing world - 330,000 a year.
AIDS researchers foresee a day when the same treatment could give many of these children a lifetime free of toxic antiviral drugs.
Richard Knox, NPR News.