Feb. 20 (UPI) — Researchers at Dusseldorf University said Monday a fifth person has been declared free of HIV after a blood stem cell transplant during that patient’s treatment for leukemia. The revelation, disclosed in a study published Monday in the scientific journal Nature Medicine, said the patient, a 53-year-old man from Dusseldorf, Germany, tested positive for HIV in 2008 and developed leukemia three years later.