Western Pacific Surveillance and Response (Nov 2014)

Seroprevalence survey of avian influenza A(H5N1) among live poultry market workers in northern Viet Nam, 2011

  • Tham Chi Dung,
  • Pham Ngoc Dinh,
  • Vu Sinh Nam,
  • Luong Minh Tan,
  • Nguyen Le Khanh Hang,
  • Le Thi Thanh,
  • Le Quynh Mai

DOI
https://doi.org/10.5365/wpsar.2014.5.2.006
Journal volume & issue
Vol. 5, no. 4
pp. 21 – 26

Abstract

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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. Discussion: 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.

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