Human Adenovirus (HAdV) Viremia in Immunocompetent Children with HAdV Infection in Respiratory Specimens: Does Viremia Predict Severity of Illness?

BACKGROUND: The interpretation of HAdV PCR from upper respiratory tract (RT) specimens can be challenging due to prolonged low grade viral shedding. We hypothesized that HAdV detection in the blood (viremia) is more common in acute HAdV infection with high respiratory viral burden (VB) compared with those with low VB in the RT. We sought to determine the frequency of HAdV viremia in immunocompetent children who have detectable HAdV in the RT. METHODS: We prospectively identified + HAdV in RT specimens from emergency department or inpatients using semi-quantitative real-time PCR (Ct <40) or multiplex respiratory viral PCR (FILMARRAY RESPIRATORY PANEL v1.7) and prospectively collected available whole blood from 8/2013 to 2/2015. Blood was considered positive for HAdV if Ct was <40 in whole blood. We compared virologic, including HAdV type from the RT and blood, and clinical characteristics between viremic and non-viremic groups using Mann–Whitney or chi-square as appropriate. RESULTS: There were 196 unique patients with + HAdV in RT specimens as well as available blood for PCR (median age=1.3 years old). Blood and RT samples were obtained on the same calendar day in 78% of patients. Among these 196 patients, 163 (83%) were hospitalized and 58 (36%) were admitted to PICU. HAdV was detected in the blood in 33% of patients. Upper respiratory tract infections were more common (P = 0.026) and the duration of fever at the time of enrollment was longer in the viremia group (3 vs. 2 days, P = 0.043). There was no difference in ICU admission between two groups. Coinfections with bacterial pathogens from sterile sites were only found in the non-viremic group (4%); these included S. aureus or pneumococcal bacteremia, E. coli urinary tract infections, or pneumococcal pneumonia. HAdV VB in RT were significantly higher in the viremia group (Ct median 25.01 vs.. 36.38, P < 0.0001). Species C was more predominant in the viremia group compared with non C (A, B/E, D, F) (P = 0.018). RT type was 100% concordant with blood type. CONCLUSION: HAdV viremia is relatively common in immunocompetent children with HAdV infection in the RT. Subjects with viremia had significantly higher VB in the RT, but this didn’t seem to be correlated with disease severity. HAdV viremia may be useful tool to add further evidence of acute HAdV infection. DISCLOSURES: A. Leber, BioFIre Diagnostics: Research Contractor and Scientific Advisor, Research support, Speaker honorarium and Travel expenses