Effect of herd size on subclinical infection of swine in Vietnam with influenza A viruses

BMC Veterinary Research

Research Article

Phuong Thanh Nguyen¹  Hung Van Vo¹  Thi Quynh Anh Le¹  Dung Kim Nguyen¹  Phuong Duy Thai¹  Phan Truong Hua¹  Duy Thanh Nguyen¹  Tien Ngoc Nguyen²  Tung Nguyen²  Diep Thi Nguyen²  Dang Hoang Nguyen³  Tho Dang Nguyen³  Hoa Thi Do³  Thanh Long To³  Yugo Shobugawa⁴  Reiko Saito⁴  Yuko Uchida⁵  Nobuhiro Takemae⁵  Takehiko Saito⁶ 

[1] Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam;Department of Animal Health, Epidemiology Division, Hanoi, Vietnam;Department of Animal Health, National Centre for Veterinary Diagnostics, Hanoi, Vietnam;Division of International Health, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan;Influenza and Prion Diseases Research Center, National Institute of Animal Health, NARO, Ibaraki, Japan;Thailand–Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand;Influenza and Prion Diseases Research Center, National Institute of Animal Health, NARO, Ibaraki, Japan;Thailand–Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand;United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan;

关键词: Active surveillance;    Influenza A virus;    Pig;    Pig farm;    Vietnam;   

DOI  :  10.1186/s12917-016-0844-z

 received in 2015-09-17, accepted in 2016-02-18,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundInfluenza A viruses of swine (IAV-S) cause acute and subclinical respiratory disease. To increase our understanding of the etiology of the subclinical form and thus help prevent the persistence of IAV-S in pig populations, we conducted active virologic surveillance in Vietnam, the second-largest pig-producing country in Asia, from February 2010 to December 2013.ResultsFrom a total of 7034 nasal swabs collected from clinically healthy pigs at 250 farms and 10 slaughterhouses, we isolated 172 IAV-S from swine at the weaning and early-fattening stages. The isolation rate of IAV-S was significantly higher among pigs aged 3 weeks to 4.5 months than in older and younger animals. IAV-S were isolated from 16 large, corporate farms and 6 family-operated farms from among the 250 farms evaluated. Multivariate logistic regression analysis revealed that “having more than 1,000 pigs” was the most influential risk factor for IAV-S positivity. Farms affected by reassortant IAV-S had significantly larger pig populations than did those where A(H1N1)pdm09 viruses were isolated, thus suggesting that large, corporate farms serve as sites of reassortment events.ConclusionsWe demonstrate the asymptomatic circulation of IAV-S in the Vietnamese pig population. Raising a large number of pigs on a farm has the strongest impact on the incidence of subclinical IAV-S infection. Given that only some of the corporate farms surveyed were IAV-S positive, further active monitoring is necessary to identify additional risk factors important in subclinical infection of pigs with IAV-S in Vietnam.

【 授权许可】

CC BY   
© The Author(s). 2016