1779. Can Human Adenovirus (HAdV) Viral Loads Distinguish Acute HAdV Infections from Incidental Shedding?
Session: Poster Abstract Session: Viral Infections; Pathogenesis and Epidemiology
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
Background:

PCR-based diagnosis for HAdV has improved our ability to diagnose HAdV infections, which are common in young children. However, the interpretation of positive PCR for HAdV can be challenging, as HAdV-C can establish low-level replication in the tonsils/adenoids and cause shedding during other illness. We previously described HAdV shedding with low viral load in patients with Kawasaki Disease.  We sought to (1) determine the frequency of nasopharyngeal (NP) HAdV detection among inpatients and outpatients seen in the emergency department (ED), and (2) determine the differences in HAdV semi-quantitative viral loads (Cts) between patients with HAdV alone vs. those who had HAdV plus another respiratory virus.

Methods:

We retrospectively reviewed pediatric HAdV-positive respiratory specimens (Ct<40) obtained from ED or inpatient units using semi-quantitative real-time PCR from August 2011 to December 2012.  Mann-Whitney or Kruskal-Wallis was used for comparisons among groups and Spearman for correlations. The standard respiratory PCR panel includes respiratory syncytial virus (RSV), parainfluenza (PIV), influenza (Flu), human metapneumovirus (hMPV), rhinovirus (HRV) and HAdV.

Results:

Of 7,083 specimens, 579 (8%) specimens were positive for HAdV. The majority of patients were <5 years (n=499, 86%). HAdV was co-detected with least one other respiratory virus in 309/579 (53%). HRV (184/309, 60%) followed by RSV (113/309, 37%), PIV (28/309, 9%), hMPV (18/309, 6%), and Flu (10/309, 3%) were identified as co-infections.  HAdV viral load was significantly higher (lower Ct) in children with HAdV alone compared with those with co-infection (Ct median: 29.2 vs. 35.2, p< 0.001). HAdV viral load was also significantly higher in outpatients vs. inpatients vs. ICU-patients (26.9 vs. 30.3 vs. 35.6; p=0.012) if HAdV was identified alone, but not in the co-infection group. There was no significant correlation between HAdV viral load and age in the HAdV alone group, whereas HAdV viral load was inversely correlated with age when there was a co-infection (R-0.113, p<0.05).

Conclusion:

A positive HAdV PCR result in NP samples should be interpreted with caution as it may represent incidental shedding.  Co-infection with another respiratory virus was associated with lower viral loads, suggesting the possibility of incidental shedding of HAdV.

Eunkyung Song, M.D, Pediatiric Infectious Disease, Nationwide Children's Hospital, Columbus, OH, Octavio Ramilo, MD, Pediatrics, Nationwide, Columbus, OH, Amy Leber, PhD, Nationwide Children's Hospital, Columbus, OH, Douglas Salamon, MB(ASCP)SV, Department of Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH and Preeti Jaggi, MD, Pediatrics, Nationwide Children's Hospital and the Ohio State University College of Medicine, Columbus, OH

Disclosures:

E. Song, None

O. Ramilo, Abbott Molecular: Grant Investigator, Grant recipient
Abbott Labs: Scientific Advisor and Speaker's Bureau, Consulting fee and Speaker honorarium
Merck: Consultant, Consulting fee
Gilead: Scientific Advisor, Consulting fee
Quidel: Scientific Advisor, Consulting fee
Roche: Consultant, Consulting fee

A. Leber, None

D. Salamon, None

P. Jaggi, None

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