Role of Human Bocavirus Respiratory Tract Infection in Hematopoietic Cell Transplant Recipients

Background. Limited data exist regarding the impact of human bocavirus (BoV) in hematopoietic cell transplant (HCT) recipients. Methods. In a longitudinal surveillance study among allogeneic HCT recipients, pre-HCT and weekly post-HCT nasal washes and symptom surveys were collected through day 100, then at least every 3 months through 1 year post-HCT at the Fred Hutchinson Cancer Research Center (2005-2010). Samples were tested by multiplex semiquantitative polymerase chain reaction (PCR) for 12 viruses. Plasma samples from BoV + subjects were analyzed by PCR. Separately, we conducted a retrospective review of HCT recipients with BoV detected in lower respiratory tract specimens. Results. Among 51 children and 420 adults in the prospective cohort, 21 distinct BoV respiratory tract infections (RTIs) were observed by 1 year post-HCT in 19 patients. Younger age and exposure to children were risk factors for BoV acquisition. Univariable models among patients with BoV RTI showed higher peak viral load in nasal samples (P =.04) and presence of respiratory copathogens (P =.03) were associated with presence of respiratory symptoms, but BoV plasma detection was not. Only watery eyes and rhinorrhea were associated with BoV RTI in adjusted models. With additional chart review, we identified 6 HCT recipients with BoV detected in lower respiratory tract specimens (incidence rate of 0.4% [9/2509] per sample tested). Although all cases presented with hypoxemia, 4 had respiratory copathogens or concomitant conditions that contributed to respiratory compromise. Conclusions. BoV RTI is infrequent in transplant recipients and associated with mild symptoms. Our studies did not demonstrate convincing evidence that BoV is a serious respiratory pathogen.