Two patients previously thought to be 'cured' of HIV after undergoing bone marrow transplants have experienced recurrences of the virus in their blood, the Boston Globe reported.

These findings, presented Thursday at an international conference of AIDS researchers, demonstrate HIV's ability to thoroughly hide within the body, according to lead scientist Dr. Timothy Henrich, of Brigham and Women's Hospital in Boston.

The two patients involved in the study both underwent bone marrow transplants after other treatments failed to cure them of Hodgkin's lymphoma - a type of blood cancer.

Both patients had battled HIV for years, but they had agreed to stop taking antiretroviral medications after undergoing their bone marrow transplants, in order to test whether the procedure had eliminated the virus from their bodies.

Though one of the patients remained HIV-free for seven weeks, the researchers soon detected a recurrence of the virus in the patient's blood, and the patient resumed taking his medication. The other patient opted to continue the study, but after eight months the researchers again detected a recurrence of HIV and put the patient back on medication.

While Henrich and his fellow researchers say the results of their study are disappointing, they believe that their findings will help lend insight into future research on potential cures for the disease.

"We go back to the drawing board," Henrich told The Boston Globe. "It's exciting science, even if it's not the outcome we would have liked."