Methods: From 2005-2011, we conducted a surveillance study of allogeneic HCT recipients in which upper respiratory samples and symptom surveys were collected weekly for the first 100 days following HCT, then every 3 months or with new respiratory symptoms for 1 year. Samples were tested by real-time RT-PCR for 15 respiratory viruses, including HRV. Unique HRV episodes were defined when ≥4 negative weeks occurred between positive samples or when a new HRV genotype was detected in consecutive samples. Samples with HRV PCR cycle threshold values <32 were sequenced at the 5’ non-coding region. Sequences with >98% match to GenBank sequences were identified as known HRV genotypes.
Results: Of 471 patients (11% ≤ 18 years), 164 (35%) were positive for HRV at least once. Sequencing was completed on 327 samples from 72 patients with 84 HRV episodes. HRV-A was the most common species identified (62% HRV-A, 18% HRV-B, 20% HRV-C). Fifty-three unique genotypes were identified. No molecular evidence of transmission was identified based on lack of significant temporal correlations between genotypes and episodes. The majority of patients demonstrated prolonged shedding of a single HRV genotype, but 9 (12.5%) had multiple illness episodes each with a unique HRV genotype identified. A total of 4/9 (44%) of these patients with multiple episodes were under 18 years of age. Of 63 patients with symptom data available, 15 (24%) were asymptomatic at time of initial viral detection.
Conclusion: HRV was the most common pathogen identified in this surveillance study of HCT recipients. Sequencing analysis showed little temporal overlap between strains, even with a significant proportion of asymptomatic patients who would not have qualified for respiratory droplet isolation. These data suggest that HRVs are most often community–acquired and that nosocomial spread is less common than expected. Enhanced prevention strategies aimed at minimizing HRV community exposures are needed.
A. P. Campbell, None
K. Jerome, None
J. Englund, None
M. Boeckh, None
S. Pergam, None