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From 2011 to 2013, the French network for the surveillance of influenza viruses in pigs (Résavip) has made it possible to conduct 629 visits in 476 farms in the context of respiratory influenza-like syndromes. While nearly 87% of visits were conducted in Brittany, a region containing 60% of the French pig population, sampling was done in a total of 14 different regions.
Nasal swabs enabled the detection of influenza A virus in 53.6% of cases and the identification of 257 viral strains. Fifty-seven percent of the detected viruses belonged to the European “avian-like swine H1N1” (H1avN1) lineage and were circulating in all the regions sampled. “Humanlike reassortant swine H1N2” (H1huN2) viruses represented 16.9% of the viruses detected but were identified only in the western part of the country, where some reassortant viruses between H1avN1 and H1huN2 were also identified. Less than 1% of the cases were found to be infected by the pandemic H1N1 virus, in regions with low pig population density. The sampled animals were essentially fattening pigs of all ages, mostly from farrow-to-finish herds. Confirmed swine flu cases in the context of this surveillance programme were detected throughout the year and were usually of average intensity. The classical epidemiological form affected pigs in all physiological stages equally, while recurrent flu (nearly 40% of cases) was reported preferentially in animals during the post-weaning period (median age of 8 weeks).
Séverine Hervé, Emmanuel Garin, Nicolas Rose, Clara Marcé, Gaëlle Simon. Réseau national de surveillance des virus influenza chez le porc (Résavip) – Résultats des trois premières années de fonctionnement. Bulletin épidémiologique, santé animale et alimentation Nº 63.
