Updated

There’s an estimated 33 million people worldwide living with HIV/AIDS, and now doctors believe one of them may have been cured of the virus after receiving a stem cell transplant in 2007, the medical journal Blood reported.

Timothy Ray Brown, an HIV-positive American living in Germany, had leukemia and was undergoing chemotherapy, when he received a transplant of stem cells from a donor carrying a rare, inherited gene mutation that seems to make carriers virtually immune to HIV infection.

The transplant appeared to wipe out both diseases, giving hope to doctors, but Dr. Anthony Fauci, director of the National Institutes of Allergy and Infectious Diseases, who has been studying HIV/AIDS for almost 30 years, said while this is an interesting proof of concept, it’s absurdly impractical.

“It’s hard enough to get a good compatible match for a transplant like this,” Fauci told FoxNews.com, “But you also have to find compatible donor that has this genetic defect, and this defect is only found in 1 percent of the Caucasian population and zero percent of the black population. This is very rare.”

Fauci said while this patient is “functionally cured” this is not something you can do with every HIV-infected individual.

“This is not prime time to me at all,” he said. “This is a very unusual situation that has little practical application for a simple reason. This donor not only had to be a good compatible match, but the donor had to have a genetic defect of cells that do not express the receptor that the HIV virus needs to enter the cell.”

Fauci also pointed to the fact that this transplant process is not only expensive, it’s incredibly painful and complicated, and requires the patient to start a whole new regimen of drugs.

“This patient is trading one poison for another. He may not have to be on antiretroviral drugs anymore, but he has to take immunosuppressant drugs now to prevent the rejection of his transplant cells. Again, what this is, is an interesting proof of concept, but it’s absolutely impractical.”

Dr. Thomas Quinn, director of Johns Hopkins Center for Global Health told FoxNews.com that he is very familiar with the “Berlin patient” case.

“This was a new report that looked much deeper into whether HIV could still be present or lurking in the body in some way, not cured, and since the transplant he remains viral free and his cells appear to be resistant to infection,” he said.

Quinn said he agrees with the researchers on this case that it would be qualified as the first HIV cure, opening the door to alternative means of curing HIV.

“He [Brown] has been without therapy for three years and appears to be free of the virus,” he said. “It gives hope to the millions of people infected with HIV that cure is a feasible option in the future.”

Even though Brown’s procedure proved to be successful, Quinn also warns that this was a rare case and a bone marrow transplant is not a cure-all for other HIV patients.

“It is a near fatal procedure that he had to have done because of the leukemia, but this procedure is very expensive and you have to be transplanted with a donor who is shown to be already resistant to HIV,” Quinn said. “You’re asking for a tall order to replicate this in the future.”

Brown’s case was published in a February 2009 issue of the New England Journal of Medicine.

Click here to read more from the journal Blood (subscription is required).