tetano
Editor, Senior Moderator
BMC Vet Res. 2016 Oct 10;12(1):227.
[h=1]Effect of herd size on subclinical infection of swine in Vietnam with influenza A viruses.[/h] Takemae N[SUP]1,[/SUP][SUP]2[/SUP], Shobugawa Y[SUP]3[/SUP], Nguyen PT[SUP]4[/SUP], Nguyen T[SUP]5[/SUP], Nguyen TN[SUP]5[/SUP], To TL[SUP]6[/SUP], Thai PD[SUP]4[/SUP], Nguyen TD[SUP]6[/SUP], Nguyen DT[SUP]4[/SUP], Nguyen DK[SUP]4[/SUP], Do HT[SUP]6[/SUP], Le TQ[SUP]4[/SUP], Hua PT[SUP]4[/SUP], Van Vo H[SUP]4[/SUP], Nguyen DT[SUP]5[/SUP], Nguyen DH[SUP]6[/SUP], Uchida Y[SUP]1,[/SUP][SUP]2[/SUP], Saito R[SUP]3[/SUP], Saito T[SUP]7,[/SUP][SUP]8,[/SUP][SUP]9[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] Influenza 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.
[h=4]RESULTS:[/h] From 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.
[h=4]CONCLUSIONS:[/h] We 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.
[h=4]KEYWORDS:[/h] Active surveillance; Influenza A virus; Pig; Pig farm; Vietnam
PMID: 27724934 DOI: 10.1186/s12917-016-0844-z
[PubMed - in process] Free full text
[h=1]Effect of herd size on subclinical infection of swine in Vietnam with influenza A viruses.[/h] Takemae N[SUP]1,[/SUP][SUP]2[/SUP], Shobugawa Y[SUP]3[/SUP], Nguyen PT[SUP]4[/SUP], Nguyen T[SUP]5[/SUP], Nguyen TN[SUP]5[/SUP], To TL[SUP]6[/SUP], Thai PD[SUP]4[/SUP], Nguyen TD[SUP]6[/SUP], Nguyen DT[SUP]4[/SUP], Nguyen DK[SUP]4[/SUP], Do HT[SUP]6[/SUP], Le TQ[SUP]4[/SUP], Hua PT[SUP]4[/SUP], Van Vo H[SUP]4[/SUP], Nguyen DT[SUP]5[/SUP], Nguyen DH[SUP]6[/SUP], Uchida Y[SUP]1,[/SUP][SUP]2[/SUP], Saito R[SUP]3[/SUP], Saito T[SUP]7,[/SUP][SUP]8,[/SUP][SUP]9[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] Influenza 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.
[h=4]RESULTS:[/h] From 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.
[h=4]CONCLUSIONS:[/h] We 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.
[h=4]KEYWORDS:[/h] Active surveillance; Influenza A virus; Pig; Pig farm; Vietnam
PMID: 27724934 DOI: 10.1186/s12917-016-0844-z
[PubMed - in process] Free full text