Received: 23 September 2019
Accepted: 28 November 2019
First Online: 17 December 2019
Ethics approval and consent to participate
: Based on the diagnostic structure of the study no ethic approval was required (see Material and Methods). Permission of `Conseil National de l’Ordre des Vétérinaires `in France to perform sampling on French pig farms was given.
: All authors have read the manuscript and agreed on publication in its current version.
: The authors declare that they have no competing interests.