Practical Aspects of PRRSV Detection in Processing Fluids

. 2020 May 4;180:105021. doi: 10.1016/j.prevetmed.2020.105021.Online ahead of print. Practical Aspects of PRRSV RNA Detection in Processing Fluids Collected in Commercial Swine Farms
Will A López 1, Jeffrey J Zimmerman 2, Phillip C Gauger 2, Karen M Harmon 2, Laura Bradner 2, Min Zhang 3, Luis Giménez-Lirola 2, Alejandro Ramirez 2, Jean Paul Cano 1, Daniel C L Linhares 4

• 1

• Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States; PIC North America, 100 Bluegrass Commons Blvd #2200, Hendersonville, TN 37075, United States.

• 2

• Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States.

• 3

• Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, Iowa 50011, United States.

• 4

• Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States. Electronic address: linhares@iastate.edu.

• PMID: 32428814
 
• DOI: 10.1016/j.prevetmed.2020.105021

Abstract

Processing fluid samples are easily collected under field conditions and provide the means to test more piglets more frequently in a practical way, thereby improving PRRSV surveillance. However, a deeper understanding of the diagnostic characteristics of this newly described sample type is still required. Therefore, the objective of this field-based study was to determine the relationship between viremic piglets and the detection of PRRSV RNA in processing fluid samples. In two PRRSV-positive breeding herds, processing fluids (n = 77) and individual piglet serum samples (n = 834) were collected from 77 litters in three sampling events and tested for PRRSV RNA. Among the 77 litters in the study, 55 litters (71.4%) contained no viremic piglets and processing fluids tested negative for PRRSV RNA. Among the 22 (28.6%) litters with ≥1 viremic piglets, 10 litters contained a single viremic piglet and 5 of the 10 processing fluids from this group tested positive for PRRSV RNA. Based on a fitted mixed effects logistic regression model, the probability of detecting PRRSV RNA in processing fluids was highly dependent on the number of viremic piglets contributing to the sample. When the within-litter prevalence was ≥39%, the probability of detecting PRRSV RNA in processing fluids was ≥95%. By extension, the results suggest that pooling processing fluids from several litters increases the probability of PRRSV RNA detection because of the greater likelihood of including multiple litters each with ≥1 viremic piglets. In contemporary breeding herds that use processing fluid samples for PRRSV surveillance, the diagnostic costs associated with testing 100% of the processing-age piglet population can be estimated at €0.077 ($0.086 USD) per pig weaned. In contrast, to achieve an equivalent testing coverage with the use of individual piglet serum samples, the diagnostic costs associated would be €4.48 ($5.00 USD) per pig weaned. Processing fluid represents a practical, reliable and efficient method to surveil breeding herds for PRRSV because it allows for continuous surveillance at a low cost.

Keywords: Monitoring; PRRS virus; Processing fluids; Surveillance; Swine.

Copyright © 2020 Elsevier B.V. All rights reserved.

Understanding and interpreting PRRSV diagnostics in the context of “disease transition stages”

Author links open overlay panelAlexandra Henao-Diaz  JuJi  Luis Giménez-Lirola  David H. Baum. Jeffrey Zimmerman

Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011. USA

https://doi.org/10.1016/j.rvsc.2020.04.023

Highlights

•

PRRSV infection is characterized by changes in its tissue distribution over time.

•

Therefore, the rate of PRRSV detection varies over time by specimen-assay selection.

•

The choice of specimen-assay must be tailored to specific PRRSV testing objectives.

Abstract

Herein we review broad issues that affect test performance for agents that produce persistent infections. Using PRRSV as an example, the relationship between “disease transition stages” and “diagnostic transition stages” is discussed using meta-analyses of diagnostic data (n = 4307 results) from the refereed literature to highlight the key issues. Although diagnostic technology will continue to improve, it may be concluded from the analysis that there can be no single best diagnostic approach; rather, the choice of specimen and test must be tailored to the specific testing objective. In most cases, meeting the testing objective(s) will require the use of more than one assay and/or specimen type.

Prediction of seasonal patterns of PRRSV detection in the USA

Prediction of seasonal patterns of porcine reproductive and respiratory syndrome virus RNA detection in the U.S. swine industry

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Giovani Trevisan, Leticia C. M. Linhares, Bret Crim, 

Poonam Dubey, Kent J. Schwartz, Eric R. Burrough, Chong Wang, Rodger G. Main, Paul Sundberg, Mary Thurn, Paulo T. F. Lages, Cesar A. Corzo, Jerry Torrison, Jamie Henningson, Eric Herrman, Gregg A. Hanzlicek, Ram Raghavan, Douglas Marthaler, Jon Greseth, Travis Clement, Jane Christopher-Hennings, David Muscatello, Daniel C. L. Linhares¹

First Published April 10, 2020 Research Article 

https://doi.org/10.1177/1040638720912406

Article information

bstract

We developed a model to predict the cyclic pattern of porcine reproductive and respiratory syndrome virus (PRRSV) RNA detection by reverse-transcription real-time PCR (RT-rtPCR) from 4 major swine-centric veterinary diagnostic laboratories (VDLs) in the United States and to use historical data to forecast the upcoming year’s weekly percentage of positive submissions and issue outbreak signals when the pattern of detection was not as expected. Standardized submission data and test results were used. Historical data (2015–2017) composed of the weekly percentage of PCR-positive submissions were used to fit a cyclic robust regression model. The findings were used to forecast the expected weekly percentage of PCR-positive submissions, with a 95% confidence interval (CI), for 2018. During 2018, the proportion of PRRSV-positive submissions crossed 95% CI boundaries at week 2, 14–25, and 48. The relatively higher detection on week 2 and 48 were mostly from submissions containing samples from wean-to-market pigs, and for week 14–25 originated mostly from samples from adult/sow farms. There was a recurring yearly pattern of detection, wherein an increased proportion of PRRSV RNA detection in submissions originating from wean-to-finish farms was followed by increased detection in samples from adult/sow farms. Results from the model described herein confirm the seasonal cyclic pattern of PRRSV detection using test results consolidated from 4 VDLs. Wave crests occurred consistently during winter, and wave troughs occurred consistently during the summer months. Our model was able to correctly identify statistically significant outbreak signals in PRRSV RNA detection at 3 instances during 2018.

Keywords cyclic, outbreak signal, PRRSV, prediction, swine pathogens, veterinary diagnostic laboratories

Front Vet Sci. 2020 Feb 18;7:68. doi: 10.3389/fvets.2020.00068. eCollection 2020.

Near Real-Time Monitoring of Clinical Events Detected in Swine Herds in Northeastern Spain.

Alba-Casals A1,2, Allue E3, Tarancon V3, Baliellas J3, Novell E3, Napp S1,2, Fraile L4.

Author information

1

IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, Barcelona, Spain.

2

The OIE Collaborating Centre for the Research and Control of Emerging and Re-emerging Diseases in Europe (IRTA-CReSA), Barcelona, Spain.

3

Grup de Sanejament Porcí, Lleida, Spain.

4

Departament de Ciència Animal, ETSEA, Universitat de Lleida-Agrotecnio, Lleida, Spain.

Abstract

Novel techniques of data mining and time series analyses allow the development of new methods to analyze information relating to the health status of the swine population in near real-time. A swine health monitoring system based on the reporting of clinical events detected at farm level has been in operation in Northeastern Spain since 2012. This initiative was supported by swine stakeholders and veterinary practitioners of the Catalonia, Aragon, and Navarra regions. The system aims to evidence the occurrence of endemic diseases in near real-time by gathering data from practitioners that visited swine farms in these regions. Practitioners volunteered to report data on clinical events detected during their visits using a web application. The system allowed collection, transfer and storage of data on different clinical signs, analysis, and modeling of the diverse clinical events detected, and provision of reproducible reports with updated results. The information enables the industry to quantify the occurrence of endemic diseases on swine farms, better recognize their spatiotemporal distribution, determine factors that influence their presence and take more efficient prevention and control measures at region, county, and farm level. This study assesses the functionality of this monitoring tool by evaluating the target population coverage, the spatiotemporal patterns of clinical signs and presumptive diagnoses reported by practitioners over more than 6 years, and describes the information provided by this system in near real-time. Between January 2012 and March 2018, the system achieved a coverage of 33 of the 62 existing counties in the three study regions. Twenty-five percent of the target swine population farms reported one or more clinical events to the system. During the study period 10,654 clinical events comprising 14,971 clinical signs from 1,693 farms were reported. The most frequent clinical signs detected in these farms were respiratory, followed by digestive, neurological, locomotor, reproductive, and dermatological signs. Respiratory disorders were mainly associated with microorganisms of the porcine respiratory disease complex. Digestive signs were mainly related to colibacilosis and clostridiosis, neurological signs to Glässer's disease and streptococcosis, reproductive signs to PRRS, locomotor to streptococcosis and Glässer's disease, and dermatological signs to exudative epidermitis.

Copyright © 2020 Alba-Casals, Allue, Tarancon, Baliellas, Novell, Napp and Fraile.

KEYWORDS: 

data mining; endemic diseases; endemic-epidemic multivariate time-series model; monitoring; swine health; web application

PMID:

 

32133377

 

PMCID:

 

PMC7040479

 

DOI:

 

10.3389/fvets.2020.00068

Comp Immunol Microbiol Infect Dis. 2020 Jan 17;69:101423. doi: 10.1016/j.cimid.2020.101423. [Epub ahead of print]

A comparison of commercial modified-live PRRSV-1 and PRRSV-2 vaccines against a dual heterologous PRRSV-1 and PRRSV-2 challenge in late term pregnancy gilts.

Yang S1, Oh T1, Cho H1, Chae C2.

Author information

1

Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.

2

Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea. Electronic address: swine@snu.ac.kr.

Abstract

This study compared the efficacy, in terms of reproductive performance, of a porcine reproductive and respiratory syndrome virus (PRRSV)-1 or PRRSV-2 modified-live virus (MLV) vaccine against a dual heterologous PRRSV-1 and PRRSV-2 challenge. Gilts were administered either the PRRSV-1 or PRRSV-2 MLV vaccine at 21 days prior to breeding and were challenged intranasally with both PRRSV species at day 93 of gestation. Vaccination of gilts with PRRSV-2 MLV vaccine resulted in improved reproductive performance in sows (e.g. duration of pregnancy) and piglet health and overall viability (e.g. increase of the number of live-born and weaned pigs, and decrease of stillborn). Vaccination of gilts with PRRSV-1 MLV vaccine was able to reduce only PRRSV-1 viremia in contrast, PRRSV-2 MLV vaccine was able to reduce both PRRSV-1 and PRRSV-2 viremia. Vaccination of gilts with PRRSV-2 MLV induced higher numbers of PRRSV-2 specific interferon-γ secreting cells (IFN-γ-SC) compared to the PRRSV-1 MLV while there was no difference in the number of PRRSV-1 specific IFN-γ-SC between the two vaccines. Taken together, the results presented here suggest that vaccination of gilts with the PRRSV-2 MLV vaccine is more efficacious against dual heterologous PRRSV-1 and PRRSV-2 challenge compared to the PRRSV-1 MLV vaccine.

Copyright © 2020 Elsevier Ltd. All rights reserved.

KEYWORDS: 

Porcine reproductive and respiratory syndrome virus; Reproductive failure; Sow; Vaccine

PMID:

 

31972500

  

DOI:

 

10.1016/j.cimid.2020.101423

Development of a biosecurity assessment tool in Japanese commercial swine farms

Prev Vet Med. 2019 Nov 15;175:104848. doi: 10.1016/j.prevetmed.2019.104848. [Epub ahead of print]

Development of a biosecurity assessment tool and the assessment of biosecurity levels by this tool on Japanese commercial swine farms.

Sasaki Y1, Furutani A2, Furuichi T3, Hayakawa Y4, Ishizeki S5, Kano R6, Koike F7, Miyashita M8, Mizukami Y9, Watanabe Y5, Otake S10; P-JET11.

Author information

1

Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan; Center for Animal Disease Control, University of Miyazaki, Miyazaki, Japan. Electronic address: yskssk@cc.miyazaki-u.ac.jp.

2

Course of Animal and Grassland Sciences, Graduate School of Agriculture, University of Miyazaki, Miyazaki, Japan.

3

Feed One Co., Ltd., Kanagawa, Japan.

4

IDEAS Swine Clinic, Chiba, Japan.

5

Summit Veterinary Services, Gunma, Japan.

6

Boehringer Ingelheim Animal Health Japan Co. Ltd., Tokyo, Japan.

7

SMC Co., Ltd., Kanagawa, Japan.

8

Eckstein Swine Service, Tokyo, Japan.

9

Akabane Animal Clinic, Aichi, Japan.

10

Swine Extension & Consulting, Inc., Niigata, Japan.

11

PRRS-Japan Elimination Team, Tokyo, Japan.

Abstract

It is well known that infectious diseases such as porcine reproductive and respiratory syndrome (PRRS) and porcine epidemic diarrhea (PED) decrease herd productivity and lead to economic loss. It is believed that biosecurity practices are effective for the prevention and control of such infectious diseases. Therefore, the objective of the present study was to investigate whether or not an association between biosecurity level and herd productivity, as well as disease status exists on Japanese commercial swine farms. The present study was conducted on 141 farms. Biosecurity in each farm was assessed by a biosecurity assessment tool named BioAsseT. BioAsseT has a full score of 100 and consists of three sections (external biosecurity, internal biosecurity and diagnostic monitoring). Production data for number of pigs weaned per sow per year (PWSY) and post-weaning mortality per year (PWM) were collected for data analysis. Regarding PRRS status, the farms were categorized into two groups: unknown or unstable and stable or negative. In addition, these farms were categorized based on their PED status, either positive or negative. The total BioAsseT score was associated with herd productivity: as total score increased by 1, PWSY increased by 0.104 pigs and PWM decreased by 0.051 % (P <  0.05). Herd productivity was associated with the score of external and internal biosecurity (P <  0.05), but did not correlate with the score of diagnostic monitoring. Regarding PRRS status, farms with an unknown or unstable status had lower total score than those with stable or negative status (P < 0.05). Similarly, PED positive farms had a lower total score compared to PED negative farms (P <  0.05). In conclusion, the present study provides evidence for the association between high biosecurity levels and increased herd productivity as well as a decreased risk for novel introductions of infectious diseases such as PED.

Copyright © 2019 Elsevier B.V. All rights reserved.

KEYWORDS: 

Biosecurity practice; Herd management; Porcine epidemic diarrhea; Porcine reproductive and respiratory syndrome; Sow

PMID:

 

31786401

  

DOI:

 

10.1016/j.prevetmed.2019.104848

Recombination of vaccine and field strains

Emerg Infect Dis. 2019 Dec;25(12):2335-2337. doi: 10.3201/eid2512.191111.

Recombination between Vaccine and Field Strains of Porcine Reproductive and Respiratory Syndrome Virus.

Wang A, Chen Q, Wang L, Madson D, Harmon K, Gauger P, Zhang J, Li G.

Abstract

We isolated and plaque purified IA76950-WT and IA70388-R, 2 porcine reproductive and respiratory syndrome viruses from pigs in the same herd in Iowa, USA, that exhibited coughing and had interstitial pneumonia. Phylogenetic and molecular evolutionary analysis indicated that IA70388-R is a natural recombinant from Fostera PRRSV vaccine and field strain IA76950-WT.

KEYWORDS: 

PRRSV; United States; pigs; porcine reproductive and respiratory syndrome virus; recombination; swine; vaccine; viruses; wild type

PMID:

 

31742529

  

DOI:

 

10.3201/eid2512.191111