title: Human enterovirus 71 strains in the background population and in hospital patients in Finland.
abstract: BACKGROUND
  Human enterovirus 71 (HEV71) is a common cause of severe outbreaks of hand-foot- and mouth disease, aseptic meningitis and encephalitis in Asian populations but has not caused such epidemics in all populations.
  
  
  OBJECTIVE
  To analyze the frequency of HEV71 in the background childhood population in Finland by screening in stool and serum samples and by measuring neutralizing antibodies against HEV71 in serum and to compare the genetic relationship of virus strains detected in asymptomatic children and those causing severe illness in Finland to the strains found in other countries.
  
  
  METHODS
  4185 stool samples and 5686 serum samples were collected and clinical symptoms recorded from children who were observed from birth. Additional stool samples were available from four children hospitalized due to EV71 infection. Samples were screened for the presence of RNA of human enteroviruses using RT-PCR and HEV71 amplicons were identified by sequencing. Phylogenetic analyses were carried out to study genetic relationships between different virus strains. Neutralizing antibodies against HEV71 were screened from 522 children.
  
  
  RESULTS
  A total of 0.3% of stool samples and two serum samples from healthy children were positive for HEV71 genome. 1.6% of the children had neutralizing antibodies against HEV71. Most infections were asymptomatic or mild in contrast to the clear symptoms in the children hospitalized due to HEV71. All viruses were C strains.
  
  
  CONCLUSIONS
  HEV71 is circulating in Finland but it is rare. No clear difference was seen between strains circulating in the Finnish background population and those found in hospitalized patients or those causing severe outbreaks worldwide.
authors.affiliation: University of Tampere, Tampere, Finland. hanna.honkanen@uta.fi
authors.forename: Hanna
authors.initials: H
authors.lastname: Honkanen
authors.forename: Sami
authors.initials: S
authors.lastname: Oikarinen
authors.forename: Outi
authors.initials: O
authors.lastname: Pakkanen
authors.forename: Tanja
authors.initials: T
authors.lastname: Ruokoranta
authors.forename: Minna M
authors.initials: MM
authors.lastname: Pulkki
authors.forename: Olli H
authors.initials: OH
authors.lastname: Laitinen
authors.forename: Sisko
authors.initials: S
authors.lastname: Tauriainen
authors.forename: Sanna
authors.initials: S
authors.lastname: Korpela
authors.forename: Maija
authors.initials: M
authors.lastname: Lappalainen
authors.forename: Tytti
authors.initials: T
authors.lastname: Vuorinen
authors.forename: Anna-Maija
authors.initials: AM
authors.lastname: Haapala
authors.forename: Riitta
authors.initials: R
authors.lastname: Veijola
authors.forename: Olli
authors.initials: O
authors.lastname: Simell
authors.forename: Jorma
authors.initials: J
authors.lastname: Ilonen
authors.forename: Mikael
authors.initials: M
authors.lastname: Knip
authors.forename: Heikki
authors.initials: H
authors.lastname: Hyöty
mesh_terms: D057134:Antibodies, Neutralizing / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003428:Cross Infection / Q000453:epidemiology* / Q000821:virology; D029821:Enterovirus A, Human / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D004769:Enterovirus Infections / Q000453:epidemiology* / Q000821:virology; D005243:Feces / Q000821:virology; D005260:Female; D005387:Finland / Q000453:epidemiology; D006760:Hospitalization; D006801:Humans; D007223:Infant; D008297:Male; D010802:Phylogeny; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016036:Seroepidemiologic Studies
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral