Distribution of Leptospira Serogroups In Swine Herds In France, 2007 - 2017

Abstract Background: Leptospirosis is a widespread zoonotic disease caused by pathogenic Leptospira and is responsible for significant economic losses in porcine livestock. Knowledge of Leptospira serogroups and their distributions is important for evaluating the relevance of leptospirosis management measures, including the use of the prophylactic vaccine recently made available in France.A retrospective study was conducted to determine the distribution of Leptospira serogroups. Pigs from across France presenting clinical signs suggestive of leptospirosis were tested by micro-agglutination test between 2007 and 2017. We used a weighted average to determine the serogroup distributions according to the MAT results, considering cross reactions.Results: A total of 19,395 pig sera, mostly from Brittany, were tested, and 22.7 % were found to be positive for at least one Leptospira serogroup. In analysing the 4346 seropositive results for which the putative infective serogroup could be defined, we found that two serogroups out of ten were much more frequent than the others: Australis (48.5 %) and Icterohaemorrhagiae (38.2 %). Other serogroups, including Autumnalis, Panama, Ballum, Tarassovi, Sejroe, Grippotyphosa, Bataviae, and Pomona, were less common. Conclusion: Although data from diagnostic laboratories are prone to selection bias, using such a large amount of data provides a relevant overview of Leptospira distribution in space and time. Extracting epidemiological information with a standardized approach could be used for surveillance and support prophylactic strategies. Along the last decade, provide protection against the serogroups Australis and Icterohaemorrhagiae could prevent most of the clinical porcine leptospirosis in France.