title: Different herd level factors associated with H1N1 or H1N2 influenza virus infections in fattening pigs.
abstract: Herd-level factors associated with European H1N1 or H1N2 swine influenza virus (SIV) infections were assessed by mean of a cross-sectional study carried out in 125 herds in France. Serum samples from 15 fattening pigs in each herd were tested by haemagglutination inhibition. Data related to herd characteristics, biosecurity, management and housing conditions were collected by questionnaire during the farm visit. Climatic conditions in the post-weaning and fattening rooms, where the sampled pigs were housed, were measured over 20 h. Factors associated with H1N1 or H1N2 sero-positive status of the herd were identified by logistic regressions for binary outcome. For both subtypes, the odds for a herd to be SIV sero-positive increased if there were more than two pig herds in the vicinity (OR=3.2, 95% confidence interval (95% CI): 1.4-7.6, p<0.01 and OR=3.5, 95% CI: 1.5-8.1 p<0.01 for H1N1 and H1N2 respectively). Different factors were specifically associated with either H1N1 or H1N2 SIV infections. The odds for a herd to be H1N1 sero-positive were significantly increased by having a large number of pigs per pen in the post-weaning room (OR=3.2, 95% CI: 1.2-8.6, p=0.02), temperature setpoints below 25 °C (OR=2.6, 95% CI: 1.1-6.4, p=0.03) and below 24 °C (OR=2.6, 95% CI: 1.1-6.1, p=0.03) for the heating device in the farrowing room and the ventilation controller, respectively, and moving the pigs to the fattening facility via a room housing older pigs (OR=3.3, 95% CI: 1.1-9.6, p=0.03). A H1N2 sero-positive status was associated with a brief down period in the farrowing room (OR=2.6, 95% CI: 1.1-6.3, p=0.03), small floor area per pig in the post-weaning pen (OR=2.9, 95% CI: 1.2-7.0, p=0.02), large-sized fattening room (OR=2.5, 95% CI: 1.1-5.9, p=0.03), lack of all-in all-out management in the fattening room (OR=2.4, 95% CI: 1.0-5.8, p=0.04) and a temperature range of less than 5 °C controlling ventilation in the fattening facilities (OR=3.2, 95% CI: 1.4-7.4, p<0.01). Factors related to external and internal biosecurity and to the control of inside climatic conditions should be considered together when implementing programmes to better control SIV infections.
authors: Anses, Unité Epidémiologie et Bien-Etre du Porc, B.P. 53, 22440 Ploufragan, France; Université Européenne de Bretagne, France. Electronic address: christelle.fablet@anses.fr.
authors: C
authors: C
authors: Fablet
authors: G
authors: G
authors: Simon
authors: V
authors: V
authors: Dorenlor
authors: F
authors: F
authors: Eono
authors: E
authors: E
authors: Eveno
authors: S
authors: S
authors: Gorin
authors: S
authors: S
authors: Quéguiner
authors: F
authors: F
authors: Madec
authors: N
authors: N
authors: Rose
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D005602:France / Q000453:epidemiology; D006385:Hemagglutination Inhibition Tests / Q000662:veterinary; D006799:Housing, Animal; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D057221:Influenza A Virus, H1N2 Subtype / Q000302:isolation & purification*; D016015:Logistic Models; D008297:Male; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D015995:Prevalence; D012621:Seasons; D016036:Seroepidemiologic Studies; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000821:virology
chemical_list: D000914:Antibodies, Viral
keywords: Biosecurity; Husbandry; Pigs; Risk factors; Swine influenza virus