Porcine reproductive and respiratory syndrome (PRRS) is endemic in most pork producing countries. In Chile, eradication of PRRS virus (PRRSV) was successfully achieved in 2009 as a result of the combined efforts of producers and the animal health authorities. In October 2013, after several years without detecting PRRSV under surveillance activities, suspected cases were confirmed on a commercial swine farm. Here, we describe the PRRS epidemic in Chile between October 2013 and April 2015, and we studied the origins and spread of PRRSV throughout the country using official surveillance data and Bayesian phylogenetic analysis. Our results indicate that the outbreaks were caused by a PRRSV closely related to viruses present in swine farms in North America, and different from the strain that circulated in the country before 2009. Using divergence time estimation analysis, we found that the 2013–2015 PRRSV may have been circulating in Chile for at least one month before the first detection. A single strain of PRRSV spread into a limited number of commercial and backyard swine farms. New infections in commercial systems have not been reported since October 2014, and eradication is underway by clearing the disease from the few commercial and backyard farms that remain positive. This is one of the few documented experiences of PRRSV introduction into a disease-free country.
Bibliographical noteFunding Information:
The Asociacion Gremial de Productores de Cerdo de Chile (ASPROCER-www.asprocer.cl) funded in part the sample collection and materials. FONDEF ID 14i10201 funded reagents/materials for sample processing and part of the stipend/salary of investigators. CONICYT-PIA Anillo1408 plays an important role in supporting collaborative projects, and funded in part the salary of investigators. We thank all personnel from the Agricultural and Livestock Service (SAG) and Chilean pork producers for their support and contributions to this study. We are grateful to Dr. Sagar Goyal (University of Minnesota) for providing MARC-145 cell line. The authors wish to thank Ms. Elana Peach-Fine who assisted in the proof-reading of this manuscript.
© 2017 Neira et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.