Viral aetiology of influenza-like illness in Belgium during the influenza A(H1N1)2009 pandemic

Abstract

The purpose of this investigation was to determine the proportion of influenza-like illness (ILI) attributable to specific viruses during the influenza A(H1N1)2009 pandemic and to describe the demographic and clinical characteristics of ILI due to respiratory viruses in Belgium. Nasopharyngeal swabs were collected from ILI patients by general practitioners (GPs) and paediatricians (PediSurv) and analysed for viruses. Of 139 samples collected from children <5 years of age by PediSurv, 86 were positive, including 28 influenza (20%), 27 respiratory syncytial virus (RSV) (19%), 21 rhinovirus (17%), 12 human metapneumovirus (hMPV) (9%) and ten parainfluenza virus (PIV) (7%). Of 810 samples received from GPs, 426 were influenza (53%). Of 312 influenza-negative samples, 41 were rhinovirus (13%), 13 RSV (4%), 11 PIV (4%) and three hMPV (1%). Influenza mostly affected the 6-15 years old age group. Other respiratory viruses were commonly detected in the youngest patients. Similar clinical symptoms were associated with different respiratory viruses. Influenza A(H1N1)2009 was the most detected virus in ILI patients during the 2009-2010 winter, suggesting a good correlation between ILI case definition and influenza diagnosis. However, in children under 5 years of age, other respiratory viruses such as RSV were frequently diagnosed. Furthermore, our findings do not suggest that the early occurrence of the influenza A(H1N1)2009 epidemic impacted the RSV epidemic in Belgium.

What We Have Learned from the Influenza A pH1N1 2009/10 Pandemic: High Clinical Impact of Human Metapneumovirus and Respiratory Syncytial Virus in Hospitalized Pediatric Patients

“…up to 44z and 51z in previous reports), the number of children positive for HMPV was unexpectedly high (3,4). Hombrouck et al also found a remarkably high HMPV infection rate (14z of positives) during the pandemic; in contrast to our study, they excluded hospitalized patients (11).…”

“…A study of virus distribution in outpatients (including adults) in Belgium found pH1N1 to be the most common virus among children under the age of 5 years during the pandemic, probably reflecting a correlation between ILI case definition and actual influenza diagnosis. However, this group was frequently coinfected by other respiratory viruses (11). The rate of negative results in our study with respect to viral etiology was only 20z.…”

Use of real-time polymerase chain reaction (rtPCR) as a diagnostic tool for influenza infection in a vaccine efficacy trial

“…As published in the literature, 15 a substantial proportion of the negative cases may have been caused by other viruses, but this was not assessed in the present study.…”

Can we distinguish respiratory viral infections based on clinical features? A prospective pediatric cohort compared to systematic literature review

“…The 47 eligible publications are listed in Table . One quarter of these studies included children aged 0 to 5 years, and 6.4% and 12.8% of studies recruited children aged 0 to 3 years and aged 0 to 2 years, respectively.…”