Respiratory syncytial virus, metapneumovirus or parainfluenza virus are likely the causative agents of acute respiratory illness in children, although other respiratory viruses also may be detected with quantitative real-time PCR, according to recent study findings published in Pediatrics.
“We found that these viruses were almost exclusively found in cases making them likely causes of acute respiratory illness, and indicating that the current diagnostic method is capable of distinguishing infection from asymptomatic infection,” Samuel Rhedin, an MD-PhD student in the unit of infectious diseases at the Center for Molecular Medicine at Karolinksa Institutet in Stockholm, told Infectious Diseases in Children. “Other viruses were detected frequently in asymptomatic children making it hard to interpret the clinical significance of a finding. However, we still believe that rhinovirus is the most common cause of acute respiratory illness.”
Rhedin and colleagues evaluated children aged 5 years and younger with acute respiratory illness and matched controls from Sept. 1, 2011, to Jan. 20, 2012. The investigators compared quantitative real-time PCR (qPCR) findings from patients with acute respiratory illness with asymptomatic controls.
Overall, 72.3% of case patients had respiratory virus detected compared with 35.4% of control patients.
Nearly 8% of case patients had parainfluenza virus (PIV) detected vs. 0.5% of controls, and PIV1 was detected in 4.3% of case patients. PIV2 was detected among two case patients and PIV3 was detected among five case patients; however, PIV1 and PIV2 were not detected among any control patients. Five percent of case patients had RSV detected compared with 0.5% of controls. Nearly 5% of case patients had human metapneumovirus (hMPV) detected compared with 1% of controls. Nearly 16% of case patients had human bocavirus (hBoV) detected compared with 4.3% of controls. The most commonly detected virus was human rhinovirus (HRV) for both case patients (47.9%) and controls (21.5%).
Fever (P=.003), increased respiratory rate (P=.035), tachycardia (P=.01), and decreased O2 saturation (P=.05) were most commonly associated with hMPV infection. Decreased O2 saturation (P=.05) also was associated with human adenovirus (HAdV); increased respiratory rate (P=.003), tachycardia (P=.01), and reported coughing (P=.017) were associated with HBoV; coryza (P=.04) and absence of fever (P=.008) were associated with HRV; and RSV was associated with increased respiratory rate (P=.04) and wheezing (P=.03).
More than one virus was detected in 20.1% of case patients. Of those, 15.2% had two viruses, 4.3% had three viruses and 0.5% had four viruses. Patients with coinfections were more likely to have severe disease compared with case patients with single infections.
“Our study provides further evidence that hMPV is a pathogen associated with severe respiratory disease in children and indicate that PCR is a reliable method for diagnosing the virus,” Rhedin said. — by Amber Cox
Samuel Rhedin can be reached at the Department of Medicine Solna Infectious Diseases Unit (CMM L8:01), Karolinska University Hospital, 171 76 Stockholm, Sweden; email: firstname.lastname@example.org.
Disclosure: The study was funded in part by the Karolinska Institutet.