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

• Published in: Western Pacific surveillance and response journal Vol. 5; no. 4; pp. 21 - 26
• Main Authors: Tham, Chi Dung, Pham, Ngoc Dinh, Vu, Sinh Nam, Luong, Minh Tan, Nguyen, Le Khanh Hang, Le, Thi Thanh, Le, Quynh Mai
• Format: Journal Article
• Language: English
• Published: Philippines World Health Organization Regional Office for the Western Pacific 01.10.2014
• Subjects: A(H5N1); Adolescent; Adult; Aged; Agricultural Workers' Diseases - blood; Agricultural Workers' Diseases - epidemiology; Agricultural Workers' Diseases - virology; Animals; Antibodies, Viral - blood; Cross-Sectional Studies; Female; Humans; Influenza A Virus, H5N1 Subtype - immunology; Influenza, Human - blood; Influenza, Human - epidemiology; Influenza, Human - virology; live poultry market workers; Male; Middle Aged; northern Viet Nam; Occupational Exposure - adverse effects; Poultry - virology; Risk Factors; Seroepidemiologic Studies; seroprevalence survey; Vietnam - epidemiology; Young Adult; Vietnam
• ISSN: 2094-7321; 2094-7313; 2094-7313
• DOI: 10.5365/wpsar.2014.5.2.006

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. 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. 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. 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.