Introduction: This study aims to determine the prevalence/ incidence of BK virus viruria, viraemia and BK virus associated nephropathy (BKVAN), and identify risk factors in local renal recipients
Materials and Methods: Kidney transplant recipients who were under the care of our centre were recruited. Recruited patient had urine cytology test. The frequency of tests were determined by their duration of transplantation: every 3 months from the time of transplantation until the end of the first year post-transplantation and then annually till 5-year post-transplant. Additional urine cytology tests were performed in patients after anti-rejection therapy. Quantification of serum BK viral load by qPCR was performed in patient who had urinary decoy cell. In patients who had serum BK viral load >10⁴ copies/ml, allograft biopsy was be arranged for definitive diagnosis of BKVAN.
Results: 467 kidney transplantation patients (268 male, 519 patient-years) were included. 35 patients were transplanted <1 year and 73 patients were transplanted between 1 and 5 year. 16, 7 and 3 patients had urinary decoy, BK viraemia >10⁴ copies/ml and BKVAN respectively. The incident rate of urinary decoy cell, significant viraemia and BKVAN were 3%, 1.6% and 0.6% respectively. 71.4% viraemic (n=7) and all (n=3) BKVAN patients were transplanted within 1 year. 4 (57.1%) viraemic and 2 (66.7%) BKVAN patient receive induction therapy with IL-2R/ATG. All viraemic and BKVAN patients were on mycophenolate based therapy at time of diagnosis. 3 (42.9%) viraemic and 1 (33.3%) BKVAN patients were on cyclosporine A. 4 (57.1%) viraemic and 2 (66.7%) BKVAN patients were on tacrolimus. None of these patients were on mTOR inhibitor.
Conclusions: BK virus infection was not uncommon in kidney transplantation in first post-transplant year. Routine BK virus screening with urine cytology and BKV qPCR could identify early infection without evidence of BKVAN.