Epidemiological investigations of the introduction of PRRSv in Chile, 2013- 2015

PLoS One. 2017 Jul 25;12(7):e0181569. doi: 10.1371/journal.pone.0181569. eCollection 2017.

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

Neira V1, Brito B1, Mena J1,2, Culhane M3, Apel MI4, Max V5, Perez P5, Moreno V6, Mathieu C6, Johow M6, Badia C6, Torremorell M3, Medina R7,8, Ortega R2.

Author information

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.

PMID:

 

28742879

 

DOI:

 

10.1371/journal.pone.0181569

Effect of immunologic solutions on sows and gilts on time-to-stability, and on production losses in breeding herds infected with 1-7-4 PRRS virus

Prev Vet Med. 2017 Sep 1;144:112-116. doi: 10.1016/j.prevetmed.2017.05.024. Epub 2017 Jun 6.

Effect of immunologic solutions on sows and gilts on time to stability, and production losses in breeding herds infected with 1-7-4 PRRSv.

Linhares DCL1, Betlach C2, Morrison RB2.

Author information

1

Iowa State University College of Veterinary Medicine, 2221 Lloyd Veterinary Medicine Center, 1600 16S Street, Ames, IA, 50010, USA. Electronic address: dcl.linhares@gmail.com.

2

University of Minnesota College of Veterinary Medicine, 385B Animal Science Veterinary Medicine Building, 1988 Fitch Avenue, St. Paul, MN, 55108, USA.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSv) is an economically significant swine pathogen causing production losses in the global swine industry. Clinical impact depends on many factors including the virus itself. One method to sub-type PRRSv is using restriction fragment length polymorphism (RFLP). The RFLP pattern 1-7-4 emerged within the United States swine industry in 2014 and has become prevalent since then. This was a field study that prospectively followed 1-7-4-infected breeding herds (n=107) and compared time to stability (TTS), time to baseline production (TTBP) and total loss per 1000 sows between herds using modified-live virus vaccine (MLV) on sows and gilts (MLV-MLV), MLV on sows and MLV in addition to field virus exposure on gilts (MLV-MLV/FVE) or not deliberately exposing sows or gilts to PRRSv (Natural-Natural). Analyses were done in SAS 9.4 and results were adjusted by selected co-variates (duration of herd closure, number of previous PRRSv outbreaks of last 3 years, weaning frequency/week, gilt development unit location, herd size and production system). Survival analysis was conducted on TTS and TTBP and regression analysis on total loss. Herds in the Natural-Natural group achieved TTS and TTBP before other herds. Herds in the MLV-MLV/FVE had the longest TTS and TTBP. The total loss was numerically least in MLV-MLV herds (1194 pigs/1000 sows) compared to MLV/MLV-FVE (1810/1000 sows) and Natural-Natural (2671/1000 sows). This study provided additional information to assist veterinarians deciding between methods of exposure to manage PRRSv infection from breeding herds.

Copyright © 2017 Elsevier B.V. All rights reserved.

KEYWORDS: 

Control; EWMA; Elimination; Live virus exposure; Modified-live virus vaccine; PRRSv; Pigs; Statistical process control; Whole herd exposure

PMID:

 

28716191

 

DOI:

 

10.1016/j.prevetmed.2017.05.024

Optisample - sample size calculator for active surveillance activities

PLoS One. 2017 Jul 18;12(7):e0176863. doi: 10.1371/journal.pone.0176863. eCollection 2017.

OptisampleTM: Open web-based application to optimize sampling strategies for active surveillance activities at the herd level illustrated using Porcine Respiratory Reproductive Syndrome (PRRS).

Alba A1, Morrison RE1, Cheeran A1, Rovira A2, Alvarez J1, Perez AM1.

Author information

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSv) infection causes a devastating economic impact to the swine industry. Active surveillance is routinely conducted in many swine herds to demonstrate freedom from PRRSv infection. The design of efficient active surveillance sampling schemes is challenging because optimum surveillance strategies may differ depending on infection status, herd structure, management, or resources for conducting sampling. Here, we present an open web-based application, named 'OptisampleTM', designed to optimize herd sampling strategies to substantiate freedom of infection considering also costs of testing. In addition to herd size, expected prevalence, test sensitivity, and desired level of confidence, the model takes into account the presumed risk of pathogen introduction between samples, the structure of the herd, and the process to select the samples over time. We illustrate the functionality and capacity of 'OptisampleTM' through its application to active surveillance of PRRSv in hypothetical swine herds under disparate epidemiological situations. Diverse sampling schemes were simulated and compared for each herd to identify effective strategies at low costs. The model results show that to demonstrate freedom from disease, it is important to consider both the epidemiological situation of the herd and the sample selected. The approach illustrated here for PRRSv may be easily extended to other animal disease surveillance systems using the web-based application available at http://stemma.ahc.umn.edu/optisample.

PMID:

 

28719658

 

DOI:

 

10.1371/journal.pone.0176863

Quantitative tools to access epidemiology of PRRS using Morrison's SHMP data

Front Vet Sci. 2017 Jun 27;4:94. doi: 10.3389/fvets.2017.00094. eCollection 2017.

A Review of Quantitative Tools Used to Assess the Epidemiology of Porcine Reproductive and Respiratory Syndrome in U.S. Swine Farms Using Dr. Morrison's Swine Health Monitoring Program Data.

Vilalta C1, Arruda AG1,2, Tousignant SJP3,4, Valdes-Donoso P1,5, Muellner P6, Muellner U6, Alkhamis MA1,7, Morrison RB1, Perez AM1.

Author information

Abstract

Porcine reproductive and respiratory syndrome (PRRS) causes far-reaching financial losses to infected countries and regions, including the U.S. The Dr. Morrison's Swine Health Monitoring Program (MSHMP) is a voluntary initiative in which producers and veterinarians share sow farm PRRS status weekly to contribute to the understanding, in quantitative terms, of PRRS epidemiological dynamics and, ultimately, to support its control in the U.S. Here, we offer a review of a variety of analytic tools that were applied to MSHMP data to assess disease dynamics in quantitative terms to support the decision-making process for veterinarians and producers. Use of those methods has helped the U.S. swine industry to quantify the cyclical patterns of PRRS, to describe the impact that emerging pathogens has had on that pattern, to identify the nature and extent at which environmental factors (e.g., precipitation or land cover) influence PRRS risk, to identify PRRS virus emerging strains, and to assess the influence that voluntary reporting has on disease control. Results from the numerous studies reviewed here provide important insights into PRRS epidemiology that help to create the foundations for a near real-time prediction of disease risk, and, ultimately, will contribute to support the prevention and control of, arguably, one of the most devastating diseases affecting the North American swine industry. The review also demonstrates how different approaches to analyze and visualize the data may help to add value to the routine collection of surveillance data and support infectious animal disease control.

KEYWORDS: 

Swine Health Monitoring Project; data sharing; epidemiology; porcine reproductive and respiratory syndrome; spatiotemporal analysis

PMID:

 

28702459

 

PMCID:

 

PMC5484771

 

DOI:

 

10.3389/fvets.2017.00094