BK DNA viral load in plasma: evidence for an association with hemorrhagic cystitis in allogeneic hematopoietic cell transplant recipients

We performed a case-control study to determine the association of BK plasma viremia with hemorrhagic cystitis (HCT) in hematopoletic cell transplant (HCT) recipients. Thirty cases of HIC (14 of which occurred after platelet engraftment with documented BK viruria [BK-HC) were compared with matched controls. Weekly plasma samples were tested for BK virus DNA by polymerase chain reaction (PCR). BK viremia detected before or during the disease was independently associated with HIC (adjusted odds ratio = 30, P <.001); BK viremia was even important before clinical symptoms of HIC occurred (odds ratio = 11, P <.001). Cases of HC and BK-HC had a significantly higher peak of BK plasma viral load than controls. BK virus was detected by in situ hybridization in bladder biopsies of 2 cases with severe HC and long-lasting BK viremia. BK virus seems to play a role in the development of HC and quantitative detection of BIK DNA in plasma appears to be a marker of BIK virus disease in HCT recipients.