Investigating nosocomial BKPyV (BK Polyomavirus) infections in pediatric hematopoietic stem cell transplantation recipients: challenges and prospects

Introduction The modes of transmission of BK Polyomavirus (BKPyV) remain incompletely understood. BKPyV infections can lead to hemorrhagic cystitis after hematopoietic stem cell transplantation (HSCT). Hospitalization in a pediatric hematology unit may represent initial exposure to BKPyV due to the high rate of viral shedding among hematology patients. This study explores the potential for nosocomial transmission of BKPyV within a hematology department. Materials and Methods Epidemiologic investigation and BKPyV genome phylogenetic analyses were conducted among individuals with BKPyV DNAuria and/or DNAemia over a three-year period in a pediatric hematology unit. Results From November 2019 to December 2022, BKPyV DNA was detected in the urine or plasma of 34 out of 173 HSCT children. An unusually high prevalence of genotype Ia BKPyV was observed in 2021, suggesting possible patient-to-patient transmission. However, despite closely related sequences, they clustered with several GenBank entries, complicating phylogenetic linkage determination. Genetic signature analysis also did not link these sequences to specific patient clinical profiles. Discussion This study highlights the complexity of establishing nosocomial transmission of BKPyV, even with viral sequence analyses. Future prospective studies should include Non-Coding Control Region (NCCR) analysis, serological data, and environmental factors to enhance understanding of BKPyV transmission routes.