Human adenovirus in nasopharyngeal and blood samples from children with and without respiratory tract infections

BACKGROUND: Human adenovirus (HAdV) is a double-stranded DNA virus associated with respiratory tract infections (RTI) in children. Using polymerase chain reaction (PCR) tests, HAdV often is detected together with other virus species, even in healthy controls. OBJECTIVES: The aim of this study was to compare molecular detection of HAdV with culture, and to examine the associations of various methods to RTI. STUDY DESIGN: Nasopharyngeal aspirates (NPA) were collected from 4319 children admitted with RTI and from 361 controls. The NPAs were examined for 23 viral and bacterial pathogens, using inhouse real-time PCR-assays based on TaqMan probes, in addition to bacterial and viral culture. HAdV concentration was evaluated semi-quantitatively from the Ct-value and quantitatively by use of ADENOVIRUS R-gene®. RESULTS: HAdV-DNA was detected in 6.1% patient samples and in 10.5% controls (p< 0.001). Compared to controls, patients had an OR of 3.8 (95% CI 1.4–10.3) for mono-detection of HAdV DNA, and an OR of 5.1 (95% CI 2.0–13.4) for HAdV-positive samples grew adenovirus by culture. HAdV DNA loads from children with RTI consisted of two clusters: one cluster with high viral loads (Ct < 30 and >106 copies/ml) and one cluster with low viral loads, whereas among the controls, nearly all had low viral loads (OR 7.8, 95% CI 2.2–27.1). In 61 available plasma samples, 16.4% were positive for HAdV DNA, all were from patients. CONCLUSION: The detection of HAdV DNA per se by qualitative PCR is not useful as a diagnostic test. Detection of HAdV by use of viral culture and a high viral HAdV DNA load are the two methods most strongly associated with RTI in children.