title: Seroprevalence survey of avian influenza A(H5N1) among live poultry market workers in northern Viet Nam, 2011.
abstract: OBJECTIVE
  Highly pathogenic avian influenza A(H5N1) is endemic in poultry in Viet Nam. The country has experienced the third highest number of human infections with influenza A(H5N1) in the world. A study in Hanoi in 2001, before the epizootic that was identified in 2003, found influenza A(H5N1) specific antibodies in 4% of poultry market workers (PMWs). We conducted a seroprevalence survey to determine the seroprevalence of antibodies to influenza A(H5N1) among PMWs in Hanoi, Thaibinh and Thanhhoa provinces.
  
  
  METHODS
  We selected PMWs from five markets, interviewed them and collected blood samples. These were then tested using a horse haemagglutination inhibition assay and a microneutralization assay with all three clades of influenza A(H5N1) viruses that have circulated in Viet Nam since 2004.
  
  
  RESULTS
  The overall seroprevalence was 6.1% (95% confidence interval: 4.6-8.3). The highest proportion (7.2%) was found in PMWs in Hanoi, and the majority of seropositive subjects (70.3%) were slaughterers or sellers of poultry.
  
  
  CONCLUSIONS
  The continued circulation and evolution of influenza A(H5N1) requires comprehensive surveillance of both human and animal sites throughout the country with follow-up studies on PMWs to estimate the risk of avian-human transmission of influenza A(H5N1) in Viet Nam.
authors: National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam .
authors: Tham Chi
authors: TC
authors: Dung
authors: National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam .
authors: Pham Ngoc
authors: PN
authors: Dinh
authors: Department of Preventive Medicine, Ministry of Health, Hanoi, Viet Nam .
authors: Vu Sinh
authors: VS
authors: Nam
authors: National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam .
authors: Luong Minh
authors: LM
authors: Tan
authors: National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam .
authors: Nguyen Le Khanh
authors: Nle K
authors: Hang
authors: National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam .
authors: Le Thi
authors: le T
authors: Thanh
authors: National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam .
authors: Le Quynh
authors: le Q
authors: Mai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000382:Agricultural Workers' Diseases / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D011200:Poultry / Q000821:virology*; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral