On reproductive and respiratory syndrome virus dissemination across pig production systems in the United States

Manuel Jara; David A. Rasmussen; Cesar A. Corzo; Gustavo Machado

This analysis detailed the evolutionary epidemiology of PRRSv among commercially related and 296 unrelated farms through continuous and discrete phylogeographic analyses. Overall, a decline in PRRSv 297 genetic diversity was observed over time. Such findings could have different explanations, one being a 298 rapid and efficient disseminating strain that was introduced into sow farms which consequently was 299 transferred to growing pig sites through regular pig movement. Another potential explanation could be 300 related to the efficacy of current interventions that local production systems have implemented, which 301 reduced the volume and frequency of newly emerging strains, suggesting a more optimistic scenario than 302 The estimated speed in which PRRSv was spreading was 39 km/year which was slightly higher 333 than previous observations in a study that used data from one production system in another U.S. region 334 The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.04.09.034181 doi: bioRxiv preprint spatial distribution of the sampled sequences (Dellicour et al., 2019) . Finally, our samples represent the 412