title: Seroprevalence of H1N1, H3N2 and H1N2 influenza viruses in pigs in seven European countries in 2002-2003.
abstract: OBJECTIVE
  Avian-like H1N1 and human-like H3N2 swine influenza viruses (SIV) have been considered widespread among pigs in Western Europe since the 1980s, and a novel H1N2 reassortant with a human-like H1 emerged in the mid 1990s. This study, which was part of the EC-funded 'European Surveillance Network for Influenza in Pigs 1', aimed to determine the seroprevalence of the H1N2 virus in different European regions and to compare the relative prevalences of each SIV between regions.
  
  
  METHODS
  Laboratories from Belgium, the Czech Republic, Germany, Italy, Ireland, Poland and Spain participated in an international serosurvey. A total of 4190 sow sera from 651 farms were collected in 2002-2003 and examined in haemagglutination inhibition tests against H1N1, H3N2 and H1N2.
  
  
  RESULTS
  In Belgium, Germany, Italy and Spain seroprevalence rates to each of the three SIV subtypes were high (> or =30% of the sows seropositive) to very high (> or =50%), except for a lower H1N2 seroprevalence rate in Italy (13.8%). Most sows in these countries with high pig populations had antibodies to two or three subtypes. In Ireland, the Czech Republic and Poland, where swine farming is less intensive, H1N1 was the dominant subtype (8.0-11.7% seropositives) and H1N2 and H3N2 antibodies were rare (0-4.2% seropositives).
  
  
  CONCLUSIONS
  Thus, SIV of H1N1, H3N2 and H1N2 subtype are enzootic in swine producing regions of Western Europe. In Central Europe, SIV activity is low and the circulation of H3N2 and H1N2 remains to be confirmed. The evolution and epidemiology of SIV throughout Europe is being further monitored through a second 'European Surveillance Network for Influenza in Pigs'.
authors.affiliation: Ghent University, Merelbeke, Belgium. kristien.vanreeth@ugent.be
authors.forename: Kristien
authors.initials: K
authors.lastname: Van Reeth
authors.forename: Ian H
authors.initials: IH
authors.lastname: Brown
authors.forename: Ralf
authors.initials: R
authors.lastname: Dürrwald
authors.forename: Emanuela
authors.initials: E
authors.lastname: Foni
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Labarque
authors.forename: Patrick
authors.initials: P
authors.lastname: Lenihan
authors.forename: Jaime
authors.initials: J
authors.lastname: Maldonado
authors.forename: Iwona
authors.initials: I
authors.lastname: Markowska-Daniel
authors.forename: Maurice
authors.initials: M
authors.lastname: Pensaert
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Pospisil
authors.forename: Guus
authors.initials: G
authors.lastname: Koch
mesh_terms: D000818:Animals; D005060:Europe; D006385:Hemagglutination Inhibition Tests; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology / Q000302:isolation & purification*; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology / Q000302:isolation & purification*; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D016036:Seroepidemiologic Studies; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000821:virology*