A little girl who was treated for HIV shortly after birth still shows no sign of infection at age three, suggesting her apparent cure was not a fluke, US researchers said Wednesday.

The story of the first child known to have been cured of HIV through early treatment with powerful doses of antiretroviral drugs -- what researchers call "sustained remission" rather than a cure -- was initially announced in March when she was two and a half.

A handful of HIV-infected adults around the world have been described in medical literature as newly free of the disease, most famously Timothy Brown, also known as "the Berlin patient," who was given a bone marrow transplant for leukemia that wiped out his HIV as well.

But no easy method has emerged to eradicate the three-decade-old human immunodeficiency virus that infects 34 million people globally and is responsible for 1.8 million deaths each year.

The girl's updated case report in the New England Journal of Medicine also sought to answer questions raised by outside experts over whether she was ever really infected, by describing DNA and RNA tests that were positive for HIV just over a day after birth.

The child was given antiretroviral drugs until the age of age 18 months and, after a year and half without treatment, no sign of the disease has returned, the article said.

"Our findings suggest that this child's remission is not a mere fluke but the likely result of aggressive and very early therapy that may have prevented the virus from taking a hold in the child's immune cells," said lead author Deborah Persaud, a virologist and pediatric HIV expert at the Johns Hopkins Children's Center.

The child's mother gave birth to her prematurely, about a month early, and had not received any prenatal care. She was unaware that she was HIV positive until she was tested at the Mississippi hospital where she delivered.

The newborn also tested positive for HIV, and the high level found in her blood suggested that she had become infected with human immunodeficiency virus while in the womb, researchers said.

She also showed signs of HIV in blood tests at 19 days of age, data that "support the authors' perspective that the infant was truly infected," said an accompanying editorial by Scott Hammer, a leading HIV scientists at Columbia University Medical Center.

"The big question, of course, is, 'Is the child cured of HIV infection?' The best answer at this moment is a definitive 'maybe,'" he wrote.

A longer term follow up of the child is needed, he said, cautioning that her case may be "unique," even as it shows a proof of principle that may lead to more rigorous studies down the road.

The child was given antiretroviral drugs for the first 15-18 months of her life, when she was lost to follow up.

Her mother brought her back to doctors at 23 months of age, saying she had last given her anti-HIV medication at age 18 months.

"This happened almost by accident," said Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases.

"It wasn't that the doctor said 'let's stop the therapy.' This is not recommended for home use," he told AFP.

Tests at 23 months were negative for HIV, and by the time the child reached 30 months of age, tests still showed no sign of HIV or HIV antibodies, said the study.

"We're thrilled that the child remains off medication and has no detectable virus replicating," said pediatrician Hannah Gay of the University of Mississippi Medical Center.

"We've continued to follow the child, obviously, and she continues to do very well," said Gay, who first treated her.

"There is no sign of the return of HIV, and we will continue to follow her for the long term."

The girl's medical team believes the reason for her success was the early intervention, and they hope to investigate whether treating other infected infants within hours or days of birth could show similar outcomes.

A US-government funded study is set to begin in low and middle income countries in 2014 that would test the method in HIV-infected newborns on a wider scale, Fauci said.