Respiratory Syncityal Virus A and B: three bronchiolitis seasons in a third level hospital in Italy

Abstract

Background Respiratory syncytial virus (RSV) is the main cause of hospitalization for bronchiolitis among infants. RSV is classified into two subtypes, A and B, whose predominance alternates during different epidemic seasons. The clinical impact of viral factors is controversial and many evidences suggest a critical role for the immune host response. Premature children are at the highest risk for severe RSV infection. The main aim of this study is to identify the different RSV subtypes circulating in the last three epidemic seasons and to evaluate whether any of them was associated with poor prognosis in term and preterm infants. Methods We performed a retrospective analysis of medical records for all patients aged less than one year which were hospitalized during the winter season between November 2015 and April 2018 with clinical diagnosis of bronchiolitis and nasopharyngeal aspirates positive for RSV. Results We enrolled 422 children, of which 50 were born preterm. During the analysis period, we observed a significant increase in the rates of oxygen supplementation and admission to intensive care unit. The evidence shows an alternating pattern in the prevalence of RSV subtypes among term born; in each epidemic season, the prevalent serotype is the cause of the majority of the cases requiring intensive care. Conversely, RSV-A is always prevalent in preterm children and caused most of the cases requiring intensive care. Conclusions During the 3 seasons analyzed, we observed an alternating prevalence of RSV A and B. While there are no differences in severity between RSV A and B in term population, RSV-A is prevalent and causes most of the severe cases in the premature group. Furthermore, an increase in RSV-related oxygen therapy and PICU admission has been documented not only in the premature population. Considering the absence of appropriate therapeutic strategies, our work emphasizes the importance of implementing prophylaxis measures against RSV and highlights the urgent need to gain knowledge about immune response to the virus, also in premature children. Electronic supplementary material The online version of this article (10.1186/s13052-019-0704-0) contains supplementary material, which is available to authorized users.

Respiratory Syncytial Virus Bronchiolitis in Infancy: The Acute Hospitalization Cost

“…The relevant role of RSV as the major etiologic agent of bronchiolitis was already described by an Italian group in 2014, and the burden of RSV-associated admission is confirmed by a prospective multicenter study performed in Spain, proving that costs were significantly higher in children positive to RSV ( 19 , 20 ). Moreover, in a recent study, we reported an increase in PICU admission rates due to RSV-bronchiolitis ( 21 ).…”

Respiratory syncytial virus subtype circulation and associated disease severity at an Australian paediatric referral hospital, 2014–2018

“…Most studies have focused on hospitalised infants, some have excluded high‐risk children, some have sampled from short time periods, and various measures of disease severity have been used. Of studies that did find a difference, most suggest that RSV‐A infection is associated with greater disease severity in children when compared to RSV‐B infection 1,9–14 …”

“…Another large, prospective study found that RSV‐A positive infants presenting to the emergency department were more likely to be admitted to hospital compared to RSV‐B positive infants 9 . Some studies concluded that RSV‐A was associated with more severe disease in preterm children 10 or that RSV‐A infected infants were significantly younger 14 . Other studies have calculated composite severity scores demonstrating that RSV‐A infection is associated with greater disease severity 12,13 .…”

“…Key differences between the subtypes arise from variations in the G surface glycoprotein 8 while the more highly conserved F protein is commonly the favoured target for preventative therapies 7 . Existing studies suggest that infection with the RSV‐A subtype is associated with increased disease severity compared to RSV‐B 1,9–14 ; however, not all studies have found a clinically important difference 15–19 …”

Respiratory Syncytial Virus in Greece, 2016–2018

“…However, the predominance of RSV subtypes in other European countries during the same winter seasons varied. In Italy, RSV-B predominated in 2016–2017 and RSV-A predominated in 2017–2018 [20], whereas in Catalonia, Spain, RSV-B was more prevalent than RSV-A during both seasons, with strains mainly classified into the BA9 and ON1 genotypes, respectively [21]. In Bulgaria, RSV-B predominated during both seasons (2016–1018) [22].…”