Frequent Respiratory Viral Infections in Children with Febrile Neutropenia - A Prospective Follow-Up Study

Söderman, Martina; Rhedin, Samuel; Tolfvenstam, Thomas; Rotzén-Östlund, Maria; Albert, Jan; Broliden, Kristina; Lindblom, Anna

One major limitation of the current study was the lack of a control cohort of neutropenic patients without fever to address the question as to whether respiratory viruses are frequently found in asymptomatic immunosuppressed children. However, the use of a longitudinal design allowed us to collect follow-up samples from patients both with and without respiratory symptoms. Only five patients at the first sampling and two patients at follow-up sampling were positive for a respiratory virus without the presence of respiratory symptoms, which suggests that the frequency of asymptomatic infections is low in this group of patients. Interestingly, RV was detected in five of these seven episodes and HCoV was detected in the other two, which are in line with other studies [13] . The presence of respiratory symptoms was significantly higher in the episodes involving only respiratory viral infection, compared with both episodes involving only septicemia and fever of unknown origin, with symptoms appearing with the onset of fever in the majority of the episodes. Peck et al. investigated the incidence of respiratory virus in patients receiving a hematopoietic stem cell transplant using longitudinally collected respiratory tract samples regardless of symptoms [27] . In line with our results, a majority of the respiratory viruses detected could be correlated with respiratory tract symptoms, with the exception of PIV, which was detected in asymptomatic patients. Infection with RV or HCoV was not investigated in that study. In addition, high viral loads were correlated to more symptoms. Our real-time-PCR technique was not validated for use in reporting clinical viral loads; thus the presented Ct-values must be interpreted with extreme caution. Nevertheless, the Ct-values <30 observed in 27 of the 39 episodes of febrile neutropenia are suggestive of high viral loads ( Table 2) . Considered together, our data suggests that respiratory viruses play an etiologic role in febrile neutropenia, but our results should be interpreted carefully, especially those regarding RV, which is commonly detected in asymptomatic patients [13] .