Epidemiology and outcome of chronic high Epstein-Barr viral load carriage in pediatric kidney transplant recipients

The development of EBV infection and PTLD is normally associated with a high EBV viral load in peripheral blood. Observations have previously identified existence of a CHL carrier state that demonstrated variable outcomes based upon the organ which was transplanted. Data defining the incidence and outcome of CHL in pediatric KTx are not well described. The charts of children undergoing isolated KTx at Children's Hospital of Pittsburgh between January 2000 and December 2014 were retrospectively reviewed. EBV loads in the peripheral blood were routinely measured as part of surveillance protocols at our center. CHL was defined as the presence of high load for >50% of samples for 6months. PTLD was defined histologically using WHO definitions. Of 188 isolated KTx recipients, we identified a total of 16 (8%) children who developed CHL carrier state. No patient developed EBV-driven late-onset PTLD. Age at the time of KTx was significantly lower in the CHL group (median 3.9years, interquartile range: IQR 2.9-6.6, P=.0004). Children in the CHL group were more likely to be EBV-seronegative prior to KTx (94%, 15/16), compared to the UVL and LVL groups (55% and 50%, respectively, P<.002). The median duration of CHL carrier state was 20months (IQR 10.7-35.8). Fifteen of the 16 CHL carriers experienced spontaneous resolution of CHL carrier state. Children in the CHL group were younger at the time of primary EBV infection (P=.023). Finally, antiviral medication was not effective in either preventing or decreasing the EBV viral load in blood (P=.84). Overall incidence of late-onset PTLD is very low compared to heart and intestinal transplant, even though KTx recipients can develop CHL carrier state. The CHL carriers in KTx recipients were EBV-seronegative prior to transplant and were younger both at the time of KTx and at the time of primary EBV infection compared to those in the UVL and HVL groups. Antivirals did not prevent EBV infection or decrease EBV viral loads.