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Herd-level factors associated with enzootic H1N1 or H1N2 swine influenza virus (SIV) infections were assessed by mean of a crosssectional 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 hours.
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. 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, low temperature setpoints for the heating device in the farrowing room and the ventilation controller in the fattening room and moving the pigs to the fattening facility via a room housing older pigs. A H1N2 sero-positive status was associated with a brief down period in the farrowing room, a small floor area per pig in the post-weaning pen, a large-sized fattening room, a lack of all-in all-out management in the fattening room and a short temperature range for the ventilation control rate in the fattening facilities.
C. Fablet, G. Simon, V. Dorenlor, F. Eono, E. Eveno, S. Gorin, S. Queguiner, F. Madec , N. Rose. Les circonstances associées à l’infection grippale des porcs en engraissement diffèrent selon le sous-type viral en cause : une enquête épidémiologique dans 125 élevages du Grand Ouest de la France. JRP, 2014.