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

We tracked the origin of the migration events leading to the current PRRSv lineages circulating among 268 the three pig systems, to determine whether detected PRRSv strains originated from within the same that were observed in all pig companies; this tendency was constant during the whole period of study 275 (Fig. 6) . When looking at the difference between local transmission against external introductions, system 276 C showed the largest number of external introductions with 73.8% of all transmission events inferred to 277 be external introductions, while systems A and B exhibited 56.6% and 58.7% respectively (Table 3) . In 278 addition, our results show that overall, the external introduction events tend to increase over time (Table 279 3). We also observed that coinciding with the month of higher incidence of PRRSv (MSHMP, 2020) ( The copyright holder for this preprint (which was not peer-reviewed) is the .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