Doctors in Germany are reporting that they think they've cured a man with HIV. But while the report is generating a huge amount of interest, many point out that the method used is hardly practical for most patients.

In 2007, Timothy Ray Brown, who had HIV for over 10 years, developed AML or acute myelogenous leukemia. He underwent a blood stem cell transplant -- a procedure similar to a bone marrow transplant often used for treating blood cancers.

Brown's stem cell donor was chosen because he was an appropriate match and carried a rare, inherited gene mutation called the CCR5 Delta 32 mutation. It's a mutation that confers natural resistance to HIV but is found in only one to three per cent of white people of European descent.

Brown's HIV also immediately appeared to go quiet and he went off his retroviral medications, researchers reported in the New England Journal of Medicine last year. But questions remained about how long the effect would last and whether the HIV would resurge.

Now, more than three years later, Brown, 44, not only shows no signs of leukemia, his blood shows no signs of HIV replication. What's more, his immune system has been restored to normal health, the researchers report in the journal Blood. His doctors now feel comfortable that he is cured of HIV.

"Our results strongly suggest that cure of HIV has been achieved in this patient," carefully write the researchers, led by Dr. Gero Hutter from Charite-University Medicine Berlin.

Bone marrow and blood stem cell transplants are effective for some blood cancers but they carry risk. They involve destroying a patient's immune system with chemotherapy drugs and radiation, then building up a new immune system with donor cells.

"Bone marrow transplants are incredibly dangerous. You are taking someone's immune system and totally renovating it with the immune system of someone else's and in the process you have to destroy a person's immune system before the new one can take hold," Dr. Neil Rau, an infectious disease expert told CTV News Channel.

"It's a cure but a very rare way to achieve a cure. It's a bit like climbing Mount Everest . . . many people don't survive the climb."

Infections can occur while the patient's immunity is suppressed, and the death rate from the procedure can be five per cent or more, Dr. Michael Saag of the University of Alabama at Birmingham and past chairman of the HIV Medicine Association, tells the Associated Press.

Still, Saag says the case proves that the understanding of HIV biology is correct -- that if all of the cells that are producing HIV are eliminated and replaced with uninfected cells, a cure appears possible.

"It's an interesting proof-of-concept that with pretty extraordinary measures, a patient could be cured of HIV," Saag told AP.

But he added that the treatment is likely far too risky to become standard therapy even if matched donors could be found. Unless someone with HIV also had cancer, a transplant would not likely be considered, he said.

Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, noted that finding enough donors with the gene mutation also makes the treatment not widely practical.

"It's hard enough to get a good compatible match for a transplant like this," he said in a statement. "But you also have to find (a) compatible donor that has this genetic defect, and this defect is only found in one per cent of the Caucasian population and zero per cent of the black population. This is very rare."