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The Rate of BK Virus Infection in Pediatric Renal Transplant Patients

Introduction BK virus-associated nephropathy is an increasing problem in renal transplant recipients. Untreated BK virus (BKV) infections lead to kidney allograft dysfunction or loss. Decreased immunosuppression is the principle treatment but predisposes to acute and chronic rejection. Screening for early detection and prevention of symptomatic BKV nephropathy may improve outcomes. The purpose of this study was to determine the incidence, clinical features and risk factors of BKV infection (viruria, viraemia, virus nephropathy) in pediatric renal transplant patients in our center. Materials and Methods We retrospectively evaluated the data of 138 renal transplant patients. Demographic data of patients, etiology of renal failure, donor types were recorded. BKV values were measured periodically by quantitative polymerase chain reaction test in urine and plasma. Kidney biopsies of patients with viremia and graft dysfunction were evaluated. Patients with and without Polyoma BK infection were compared to assess risk factors in terms of chronic renal failure etiology, donor types, immunosuppressive treatments, ureteral stent, acute rejection episodes, and accompanying viral infection. Results BKV infection was detected in 12 patients (8.69%). Twelve patients (100%) developed BKV viruri; 7 patients (75%) developed BKV viremia; 4 patients (33.3%) developed BKV nephropathy. BKV replication appeared in the first year after renal transplantation (median, 11th month). Seven patients remained asymptomatic, renal biopsy was performed in five patients who had viremia and/or elevated serum creatinine level. BKV nephropathy was developed in 4 (2.89%) of all renal transplant patients. Acute humoral rejection was present in 3 (75%) of BKV nephropathy patients, acute rejection was present in 25% of BKV (+) patients. Graft loss developed in 2 (16.6%) of BKV (+) patients. Patients with BKV infection gender, age of transplantation, donor type, etiology of renal failure, immunosuppressive treatment, ureteral stent, acute rejection were similar when compared to patients without BKV infection. Accompanying CMV infection were significantly higher in patients with BKV infection (p=.013). Rate of acute rejection, presence of ureteral stent, CMV infection association and graft loss were significantly higher in BKV nephropathy (p<.01). Conclusions BKV infection is common in pediatric renal transplant patients. Although BKV infection does not significantly affect short-term renal function; the risk of developing graft loss is still high in patients with BKV nephropathy despite the treatment. CMV infections are most commonly associated with BKV infection, with patients having an increased risk of infection due to immunosuppression. Close monitoring, early detection and diagnosis have a significant effect on the prognosis of polyomavirus BK infection in pediatric renal transplant patients.