Introduction: Advancement in the immunosuppression has resulted in better graft survival but risk of infection following kidney transplantation remains high. BK virus is a challenging infection to manage and associates with poor graft survival. In this study we aim to evaluate incidence and risk factors of BK virus infection in kidney allograft recipients aged less than 21 years.
Methods: All kidney allograft recipients between 2017 to April 2024 were assess for eligibility. Patient should have age less than 21 years at time of transplantation and minimum follow-up duration of 6 months to be eligible for this study. Patients with graft failure within three months of transplantation were excluded. If a patient received more than one transplant, each counted as discrete event. Participants were routinely screened 2-3 months interval till 2 years during two years following transplantation and 6 monthly interval thereafter. Between January 2017 to March 2024, surveillance for BK virus infection was done using urine samples and in last one year our unit has employed plasma BK virus PCR based screening. BK viuria defined as urine BK virus DNA PCR more than 107 viremia defined as BK virus DNA PCR load in plasma >103copies/mL.
Results: In this study we included 71 patients with age at kidney transplantation was 13.7 (3.2) years.  Mean follow up duration 3.36 (2.0) years. Overall, 20 (28.5%) patients had evidence of BK virus infection. Eleven patients (15.5%) patient only had BK viuria and 9 (12.8%) patients had BK viremia. Of all 71 patients enrolled into this study, only 3 (4.2%) had BK virus nephropathy on allograft biopsy performed to allograft dysfunction or persistent of BK viremia. Median age at detection of BK DNA PCR in urine or plasma was 6 months (IQR: 3 to 12 months). Estimated GFR at last follow up was lower in children with confirmed BK virus infection than those without this (57.3 vs 50.4 mL/min/1.73m2). We did not find significant association between BK virus infection and induction therapy, type of maintenance immunosuppressive agents. We could not demonstrate association between acute rejection and BK virus infection (P=0.21)
Conclusion: BK virus infection is not uncommon in pediatric kidney allograft recipients. BK infection associates with lower eGFR at last follow up visit.