Epidemiological investigations of the introduction of porcine reproductive and respiratory syndrome virus in Chile, 2013-2015

Abstract

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.

Detection of porcine reproductive and respiratory syndrome virus ( PRRSV ) 1‐7‐4‐type strains in Peru

“…While differences in virulence were reported for US PRRSV 1-7- Figure 1) (Neira et al, 2017;Ramos et al, 2018). Importantly, the later reported the first detection of PRRSV in 2017 (Ramos et al, 2018).…”

“…The factors underlying the increased disease incidence remain poorly understood. It is important to note, however, that other countries in South America, including Chile and, most recently, Uruguay also recently reported PRRSV outbreaks (Figure ) (Neira et al., ; Ramos et al., ). Importantly, the later reported the first detection of PRRSV in 2017 (Ramos et al., ).…”

“…Sequence analyses of the ORF7 of the Uruguayan PRRSV strains revealed a close relationship of the virus with the historical PRRSV strain VR2385 (Ramos et al., ). Whereas the virus recently circulating in Chile is related to PRRSV strains detected in the US in 2012 (Neira et al., ).…”

Infection of novel reassortant H1N2 and H3N2 swine influenza A viruses in the guinea pig model

“…This lineage has frequently been found in commercial swine farms since 2012 [ 4 ]. Hence, one plausible explanation is that the backyard farm virus could be a result of a spillover event from a commercial farm, a situation that has been reported in Chile for other swine viruses such as porcine reproductive and respiratory syndrome virus [ 26 ].…”

First-time detection of porcine reproductive and respiratory syndrome virus (PRRSV) infection in Uruguay

“…In fact, most PRRSV type 2 isolates from South America and Asia were introduced through the movement of porcine livestock or semen trade (OIE, ). Indeed, these routes of entry might be likely involved in the PRRSV outbreak in Chile in 2013 (Neira et al., ) and may also be responsible for the introduction of the virus into Uruguay. Since 2007, Uruguay has imported animals or semen from Brazil, Spain and the Netherlands.…”