Impact of rhinovirus nasopharyngeal viral load and viremia on severity of respiratory infections in children

Abstract

There are few and partially discordant data regarding nasopharyngeal rhinovirus (RV) load and viremia, and none of the published studies evaluated the two variables together. The aim of this study was to provide new information concerning the clinical relevance of determining nasopharyngeal viral load and viremia when characterising RV infection. Nasopharyngeal swabs were obtained from 251 children upon their admission to hospital because of fever and signs and symptoms of acute respiratory infection in order to identify the virus and determine its nasopharyngeal load, and a venous blood sample was taken in order to evaluate viremia. Fifty children (19.9 %) had RV-positive nasopharyngeal swabs, six (12 %) of whom also had RV viremia: RV-C in four cases (66.6 %), and RV-A and RV-B in one case each. The RV nasopharyngeal load was significantly higher in the children with RV viremia (p < 0.001), who also had a higher respiratory rate (p = 0.02), white blood cell counts (p = 0.008) and C-reactive protein levels (p = 0.006), lower blood O2 saturation levels (P = 0.005), and more often required O2 therapy (p = 0.009). The presence of RV viremia is associated with a significantly higher nasopharyngeal viral load and more severe disease, which suggests that a high nasopharyngeal viral load is a prerequisite for viremia, and that viremia is associated with considerable clinical involvement.

Rhinovirus Viremia in Patients Hospitalized With Community-Acquired Pneumonia

“…Our findings were similar to several international reports of RV viremia detected by RT-PCR in children with acute respiratory RV infections [5–7]. A study from Greece detected RV viremia in 10 of 88 (11.4%) children presenting with acute respiratory symptoms ranging from common colds to pneumonia [5]; a study from Italy detected RV viremia in 6 of 50 (12.0%) children with fever and acute respiratory symptoms [6]; and a study from Japan detected RV viremia in 30 of 243 (12.3%) children hospitalized in the Philippines with severe lower respiratory tract infections [7]. Although these studies examined RV respiratory tract infections of varied clinical severity among mostly young children, our study was larger, included all age groups, and focused on hospitalized patients diagnosed with CAP, of which nearly 90% of pneumonias were subsequently confirmed on radiographic review.…”

Superiority of Digital Reverse Transcription-PCR (RT-PCR) over Real-Time RT-PCR for Quantitation of Highly Divergent Human Rhinoviruses

“…In comparison, other reports on the quantification of HRV used only consensus RT-qPCR assays, quantified from standard curves generated from a single HRV genotype, and tested a limited number of HRV genotypes (14)(15)(16). Nevertheless, our findings confirm the results from some of these studies and show that assay quantification ability is linked to target variability and that accurate HRV quantification by a single RT-qPCR assay is not feasible for all HRV genotypes (17,18).…”

Human Rhinovirus Infection in Children with Cystic Fibrosis

“…A plasmid containing the corresponding target viral sequence was then used to quantify the positive samples, as described previously (8). The quantitative results were expressed as log 10 RNA copy numbers/mL of nasopharyngeal swab after data multiplication by an appropriate dilution factor.…”

“…The real-time reverse transcription-polymerase chain reaction (RT-PCR) assay was performed using the iAg-Path-ID One-Step RT-PCR Kit (Applied Biosystems, Foster City, CA, USA), and the primers and probe sequences employed have been previously described (7,8). The PCR products were purified using the Wizard SV Gel and PCR Clean-Up System (Promega, Milan, Italy), and the purified products were sequenced in both the directions using the same forward and reverse primers as those used in PCR.…”