title: Frequent detection of respiratory viruses without symptoms: toward defining clinically relevant cutoff values.
abstract: Highly sensitive techniques, such as PCR, have greatly improved the detection of respiratory viruses. However, the sensitivity of PCR tests also complicates clinical interpretation, as the presence of small amounts of viral targets may not necessarily have clinical relevance. We performed a prospective case-control study in asymptomatic and symptomatic young children. PCR detection of 14 respiratory viruses was performed in nasal washes, and results were quantified in copies per milliliter. A total of 141 cases and 157 controls were included. In 72% of the cases and 28% of the controls, at least one virus was identified. When stratified for age, at least one virus was identified in 47% of the controls younger than 1 year old. Rhinovirus (RV) was frequently detected in both symptomatic and asymptomatic individuals. Receiver operating characteristic analysis for quantitative rhinovirus detection showed that cutoff values for clinical relevance are feasible for RV. In contrast to rhinovirus, respiratory syncytial virus (RSV) was rarely detected in controls, suggesting that a positive RSV test result is almost always of clinical relevance, independent of viral quantity. In conclusion, our study shows that asymptomatic carriage of a respiratory virus occurs frequently in young children. However, significant differences in the amount of virus present were observed between cases and controls. This suggests that defining cutoff levels should be feasible and represents the next necessary step for diagnosing viral respiratory infections using molecular tests.
authors.affiliation: Department of Medical Microbiology1 and Department of Pediatrics,2 Academical Medical Centre, University of Amsterdam, Amsterdam, Netherlands. R.R.Jansen@amc.uva.nl
authors.forename: Rogier R
authors.initials: RR
authors.lastname: Jansen
authors.forename: Joanne
authors.initials: J
authors.lastname: Wieringa
authors.forename: Sylvie M
authors.initials: SM
authors.lastname: Koekkoek
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Visser
authors.forename: Dasja
authors.initials: D
authors.lastname: Pajkrt
authors.forename: Richard
authors.initials: R
authors.lastname: Molenkamp
authors.forename: Menno D
authors.initials: MD
authors.lastname: de Jong
authors.forename: Janke
authors.initials: J
authors.lastname: Schinkel
mesh_terms: D058070:Asymptomatic Diseases; D002353:Carrier State / Q000821:virology*; D016022:Case-Control Studies; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009297:Nasal Mucosa / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods*; D015995:Prevalence; D011446:Prospective Studies; D012372:ROC Curve; D012141:Respiratory Tract Infections / Q000821:virology*; D012680:Sensitivity and Specificity; D019562:Viral Load; D014773:Virology / Q000379:methods*; D014777:Virus Diseases / Q000821:virology*; D014780:Viruses / Q000235:genetics / Q000302:isolation & purification*