Infection with multiple viruses is not associated with increased disease severity in children with bronchiolitis

Abstract

Background: The clinical relevance of parallel detection of multiple viruses by real-time polymerase chain reaction (RT-PCR) remains unclear. This study evaluated the association between the detection of multiple viruses by RT-PCR and disease severity in children with bronchiolitis.

Methods: Children less than 2 years of age with clinical symptoms of bronchiolitis were prospectively included during three winter seasons. Patients were categorized in three groups based on disease severity; mild (no supportive treatment), moderate (supplemental oxygen and/or nasogastric feeding), and severe (mechanical ventilation). Multiplex RT-PCR of 15 respiratory viruses was performed on nasopharyngeal aspirates.

Results: In total, 142 samples were obtained. Respiratory Syncytial virus (RSV) was the most commonly detected virus (73%) followed by rhinovirus (RV) (30%). In 58 samples (41%) more than one virus was detected, of which 41% was a dual infection with RSV and RV. In RSV infected children younger than 3 months, disease severity was not associated with the number of detected viruses. Remarkably, in children older than 3 months we found an association between more severe disease and RSV mono-infections.

Conclusion: Disease severity in children with bronchiolitis is not associated with infection by multiple viruses. We conclude that other factors, such as age, contribute to disease severity to a larger extent.

Figure 1

Frequencies of viruses detected as a single virus or in combination with other viruses. Numbers in bars represent the absolute numbers of infection per virus. RSV, respiratory syncytial virus; RV, rhinovirus; AdV, adenovirus; EV, enterovirus; hMPV, human metapneumovirus; IV, influenza virus; hBoV, human bocavirus; CoV, coronavirus; PIV, para‐influenza virus; PeV, parechovirus.

Figure 2

Percentages of infections caused by RSV (mono) or RSV and one or more other viruses (multiple) in children (A) younger and (B) older than 3 months of age for the different severity groups. Numbers in bars are absolute numbers.