Respiratory infections positive for human respiratory syncytial virus (RSV) subtype A were characterised in children admitted to hospitals in Rome and Ancona (Italy) over the last three epidemic seasons. Different strains of the novel RSV-A genotype ON1, first identified in Ontario (Canada) in December 2010, were detected for the first time in Italy in the following 2011/12 epidemic season. They bear an insertion of 24 amino acids in the G glycoprotein as well as amino acid changes likely to change antigenicity. By early 2013, ON1 strains had spread so efficiently that they had nearly replaced other RSV-A strains. Notably, the RSV peak in the 2012/13 epidemic season occurred earlier and, compared with the previous two seasons, influenza-like illnesses diagnoses were more frequent in younger children; bronchiolitis cases had a less severe clinical course. Nonetheless, the ON1-associated intensive care unit admission rate was similar, if not greater, than that attributable to other RSV-A strains. Improving RSV surveillance would allow timely understanding of the epidemiological and clinicopathological features of the novel RSV-A genotype.

Background: Preliminary results suggest that pertussis infection might be considered in infants during a seasonal respiratory syncytial virus (RSV) outbreak.Methods: In order to analyze clinical features and laboratory findings in infants with pertussis hospitalized for acute respiratory symptoms during a seasonal RSV outbreak, we conducted a retrospective single-center study on 19 infants with pertussis (6 boys; median age 72 days) and 19 matched controls (RSV-bronchiolitis), hospitalized from October 2008 to April 2010.B. pertussisand RSV were detected from nasopharyngeal washes with Real Time-PCR.Results: Infants with pertussis were less often breastfeed than infants with RSV bronchiolitis (63.2% vs 89.5%; p <0.06). Clinically, significantly fewer infants with pertussis than controls had more episodes of whooping cough (63.2% vs 0.0%; p < 0.001) and also less frequently fever at admission (15.8% vs 68.4%; p <0.01), apnea (52.6% vs 10.5%; p <0.006), and cyanosis (52.6% vs 10.5%; p < 0.006). Infants with pertussis had more often no abnormal chest sounds on auscultation than infants with RSV bronchiolitis (0% vs 42,1%; p < 0.005). The absolute blood lymphocyte and eosinophil counts were higher in infants withB. pertussisthan in controls with bronchiolitis (23886 ± 16945 vs 10725 ± 4126 cells/mm³, p < 0.0001 and 13.653 ± 10.430 vs 4.730 ± 2.400 cells/mm³, p < 0.001). The molecular analysis of 2B. pertussisisolates forptxA1,ptxP3, andprn2genes showed the presence of gene variants.Conclusions: When infants are hospitalized for acute respiratory symptoms, physicians should suspect a pertussis infection, seek for specific clinical symptoms, investigate lymphocyte and eosinophil counts and thus diagnose infection early enough to allow treatment.

The relationship between viral infection, host immune response in infants with respiratory syncytial virus (RSV) bronchiolitis and subsequent wheezing is discussed. We measured RSV-RNA load and interferon-λ1–3 expression in the nasopharyngeal washings from 68 infants hospitalized for RSV bronchiolitis, and wheezing was assessed 36 months after the first episode of bronchiolitis. Higher RSV-RNA load and higher interferon-λ2/3 levels were found in children with recurrent wheezing at 36-month follow-up.