title: A 4-year Study on Epidemiologic and Molecular Characteristics of Human Parechoviruses and Enteroviruses Circulating in Children Younger Than 5 Years in Northern Italy.
abstract: Human parechovirus (HPeV) and enterovirus (EV) infections are widespread and can lead to a broad range of symptoms, from the common cold to severe disease (SD). Because of the lack of Italian data, this 4-year retrospective cross-sectional study aimed to investigate the frequency, seasonality and molecular characteristics of EV and HPeV circulating in children younger than 5 years.
  
  
  
  A total of 812 samples were collected from children ≤5 years (56.5% males; median age: 20.6 months; interquartile range: 30.1 months) from September 2010 to August 2014. Two real-time RT-PCR assays were used for EV/HPeV and EV-D68 detection. Phylogenetic analysis was performed on the EV-VP1 gene and the HPeV-VP3/VP1 junction.
  
  
  
  16.1% and 5.2% of samples were EV- and HPeV-positive, respectively. One sample was EV-D68-positive. The majority (nearly 80%) of EV/HPeV-positive samples was detected in children ≤3 years, during the summer/autumn seasons. The risk of EV infection was higher in children presenting with SD, whereas the risk of infection from HPeV was higher in infants ≤1 year. Most (61.7%) of molecularly characterized EVs belonged to species B, followed by A (29.4%). The majority (66.7%) of characterized HPeVs were type 1, followed by types 3 (20%) and 6 (13.3%).
  
  
  
  This study shows the significant impact of EV/HPeV circulation in children, particularly among those ≤3 years and during and early autumn, with different pattern of viral strains. The implementation of a national surveillance system could clarify the epidemiologic and clinical characteristics of these viruses in the general population.
authors.affiliation: From the Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bubba
authors.forename: Marianna
authors.initials: M
authors.lastname: Martinelli
authors.forename: Laura
authors.initials: L
authors.lastname: Pellegrinelli
authors.forename: Valeria
authors.initials: V
authors.lastname: Primache
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Tanzi
authors.forename: Elena
authors.initials: E
authors.lastname: Pariani
authors.forename: Sandro
authors.initials: S
authors.lastname: Binda
mesh_terms: D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004770:Enterovirus / Q000145:classification / Q000235:genetics*; D004769:Enterovirus Infections / Q000453:epidemiology* / Q000821:virology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D008297:Male; D030061:Parechovirus / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D010850:Picornaviridae Infections / Q000453:epidemiology* / Q000821:virology*; D012189:Retrospective Studies; D012621:Seasons