title: Evidence for avian H9N2 influenza virus infections among rural villagers in Cambodia.
abstract: BACKGROUND
  Southeast Asia remains a critical region for the emergence of novel and/or zoonotic influenza, underscoring the importance of extensive sampling in rural areas where early transmission is most likely to occur.
  
  
  METHODS
  In 2008, 800 adult participants from eight sites were enrolled in a prospective population-based study of avian influenza (AI) virus transmission where highly pathogenic avian influenza (HPAI) H5N1 virus had been reported in humans and poultry from 2006 to 2008. From their enrollment sera and questionnaires, we report risk factor findings for serologic evidence of previous infection with 18 AI virus strains.
  
  
  RESULTS
  Serologic assays revealed no evidence of previous infection with 13 different low-pathogenic AI viruses or with HPAI avian-like A/Cambodia/R0404050/2007(H5N1). However, 21 participants had elevated antibodies against avian-like A/Hong Kong/1073/1999(H9N2), validated with a monoclonal antibody blocking ELISA assay specific for avian H9.
  
  
  CONCLUSIONS
  Although cross-reaction from antibodies against human influenza viruses cannot be completely excluded, the study data suggest that a number of participants were previously infected with the avian-like A/Hong Kong/1073/1999(H9N2) virus, likely due to as yet unidentified environmental exposures. Prospective data from this cohort will help us better understand the serology of zoonotic influenza infection in a rural cohort in SE Asia.
authors.affiliation: Naval Medical Research Unit #2/National Institute of Public Health, Phnom Penh, Cambodia.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Blair
authors.forename: Shannon D
authors.initials: SD
authors.lastname: Putnam
authors.forename: Whitney S
authors.initials: WS
authors.lastname: Krueger
authors.forename: Channimol
authors.initials: C
authors.lastname: Chum
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Wierzba
authors.forename: Gary L
authors.initials: GL
authors.lastname: Heil
authors.forename: Chadwick Y
authors.initials: CY
authors.lastname: Yasuda
authors.forename: Maya
authors.initials: M
authors.lastname: Williams
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Kasper
authors.forename: John A
authors.initials: JA
authors.lastname: Friary
authors.forename: Ana W
authors.initials: AW
authors.lastname: Capuano
authors.forename: Vonthanak
authors.initials: V
authors.lastname: Saphonn
authors.forename: Malik
authors.initials: M
authors.lastname: Peiris
authors.forename: Hongxia
authors.initials: H
authors.lastname: Shao
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Perez
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Gray
mesh_terms: D000328:Adult; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002160:Cambodia / Q000453:epidemiology; D004196:Disease Outbreaks; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D053127:Influenza A Virus, H9N2 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D011446:Prospective Studies; D012424:Rural Population / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral
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