Vet Microbiol

. 2021 Sep 20;262:109240.

 doi: 10.1016/j.vetmic.2021.109240. Online ahead of print.

Disinfection and conditions associated with thermo-assisted drying and decontamination inconsistently produce negative PRRSV rRT-PCR results on metal surfaces

Rita Anne Neat 1, Zhang Jianqiang 2, Hai Hoang 3, Lauren McKeen 4, Christine L Mowrer 5, Derald J Holtkamp 6

Affiliations 

Affiliations

• 1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: ritaneat@iastate.edu.
• 2Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: jqzhang@iastate.edu.
• 3Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: hai.hoangthanh@hcmuaf.edu.vn.
• 4Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: lamckeen@iastate.edu.
• 5Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: clmowrer@iastate.edu.
• 6Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: holtkamp@iastate.edu.

• PMID: 34600200
 
• DOI: 10.1016/j.vetmic.2021.109240

Abstract

Because contaminated livestock trailers are a significant risk for transmitting viruses between herds, various methods of washing, disinfecting, and thermo-assisted drying and decontamination (TADD) have been evaluated for their effectiveness in inactivating porcine reproductive and respiratory syndrome virus (PRRSV) on contaminated surfaces. Information on when to expect negative qRT-PCR results after adequate trailer sanitation is lacking. The objective of this study was to evaluate whether there are conditions associated with washing-disinfectant-TADD procedures that will consistently produce a negative qRT-PCR result for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV on metal surfaces. 144 diamond plate aluminum coupons were spiked with PRRSV or phosphate-buffered saline (PBS) and treated with a designated disinfectant protocol. Disinfectants evaluated included multiple accelerated® hydrogen peroxide (AHP) disinfectants and a quaternary ammonium and glutaraldehyde combination disinfectant. Disinfectant was applied for 5 or 60 minutes of contact time at either 20 °C or -10 °C in a matrix of feces or PBS. All coupons were heated until the surface temperature of the coupon reached 71 °C and then held for 10 minutes to simulate TADD under field conditions. Post-treatment swabs for all treatment groups, except negative control groups, were positive by PRRSV qRT-PCR. Under the conditions evaluated in this study, consistently negative qRT-PCR results after treatments were not found. Therefore, for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV, alternatives to qRT-PCR should be explored.

Keywords: PCR; PRRSV; Swine; biosecurity.

Copyright © 2021 Elsevier B.V. All rights reserved.

 Transbound Emerg Dis

. 2021 Sep 23.

 doi: 10.1111/tbed.14327. Online ahead of print.

Description of changes of key performance indicators and PRRSV shedding over time in a naïve breeding herd following a PRRS MLV exposure

Giovani Trevisan 1, Clayton Johnson 2, Neil Benjamin 2, Laura Bradner 1, Daniel C L Linhares 1

Affiliations 

• PMID: 34553831
 
• DOI: 10.1111/tbed.14327

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is an important economic swine disease. The usage of PRRS modified live vaccines (MLV) is the predominant breeding herd immunologic solution used in the United States to minimize the economic losses associated with wild-type PRRS infection. Most of the current information on the effects of contemporary PRRS MLV vaccination on breeding herd performance under field conditions comes from herds with previous PRRSV exposure. Hence, there is little information on key performance indicators (KPI) changes after the exposure to a PRRS MLV in PRRSV-naïve breeding herds. The main objective of this longitudinal observational study was to describe selected KPI changes in a naïve breeding herd after PRRS MLV exposure. The secondary objective was to describe the pattern of detection of PRRSV RNA by RT-qPCR in processing fluid samples. There were transient increases for mummies during weeks 4-23 (+0.86%); increased pre-weaning mortality on weeks 3-5 (+3.76%); decrease in live born on weeks 4-5 (-0.46) leading to a decreased pig weaned/litter on weeks 5-10 (-0.69), and increased repeated services on weeks 3-23 (+5.53%). Transient changes observed after PRRS MLV exposures did not moved total pigs weaned to outside the control intervals. Starting on week 83 and for 53 consecutive weeks, there was no PRRSV detection in processing fluids, even though two whole-herd MLV exposures occurred within that period. This article is protected by copyright. All rights reserved.

Keywords: KPI; PRRSV MLV vaccine; naïve breeding herd; swine.

 Vet Microbiol

. 2021 Aug 12;261:109190.

 doi: 10.1016/j.vetmic.2021.109190.Online ahead of print.

Probability of PRRS virus detection in pooled processing fluid samples

Will A López 1, Phillip C Gauger 2, Karen M Harmon 2, Derald J Holtkamp 2, Jean Paul Cano 3, Nubia Macedo 2, Min Zhang 4, Gustavo S Silva 2, Jose Angulo 5, Jeffrey J Zimmerman 2, Daniel C L Linhares 6

Affiliations 

Affiliations

• 1Veterinary 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.
• 2Veterinary 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.
• 3Veterinary 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; Pipestone Veterinary Services, 1300 US-75, Pipestone, MN 56164, United States.
• 4Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, United States.
• 5Zoetis, Parsippany, NJ, United States.
• 6Veterinary 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: 34411996
 
• DOI: 10.1016/j.vetmic.2021.109190

Abstract

There has been a tremendous increase in recent years of population-based diagnostic monitoring and surveillance strategies in swine populations. One example is the use of processing fluids (PF) to screen breeding herds for porcine reproductive and respiratory syndrome virus (PRRSV) activity. An important question from practitioners using such methods is on how intensively can the sample be pooled. More specifically, processing fluids of how many litters can be pooled into a single sample for diagnostic testing to preserve a high probability of PRRSV RNA detection at low prevalence situations? The objective of this study was to model the effect of pooling PF samples on the probability of PRRSV RNA detection. For this study, a PRRSV-positive PF field sample with a RT-rtPCR quantification cycle (Cq) value of 28 was selected to represent a litter of 11 pigs with a single viremic piglet. PF samples from a PRRSV-naïve herd were used to perform 6 replications of 8 two-fold serial dilutions of the PRRSV-positive sample, thus modeling the pooling effect (dilution). Each two-fold dilution represented an increase in the number of PRRS-negative pigs in the sample by a factor of 2. Samples were tested for PRRSV RNA by RT-rtPCR and the data was analyzed using linear and probit regression models. There was an average increment of 1.37 points in Ct for each two-fold dilution. The estimated probability of testing positive on RT-rtPCR was 43 %, 80 %, and 95 % when there was a single PRRSv-positive piglet among 784, 492, and 323 PRRSv-negative piglets contributing to the sample respectively. Results from this study support the practice of collecting and aggregating PF samples from multiple litters for PRRSV RNA testing.

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

Copyright © 2021 Elsevier B.V. All rights reserved.

Factors associated with PRRS outbreaks in US breeding herds

 Prev Vet Med

. 2020 Oct;183:105128.

 doi: 10.1016/j.prevetmed.2020.105128. Epub 2020 Sep 1.

Spatial relative risk and factors associated with porcine reproductive and respiratory syndrome outbreaks in United States breeding herds

Juan M Sanhueza 1, Mark A Stevenson 2, Carles Vilalta 3, Mariana Kikuti 4, Cesar A Corzo 4

Affiliations 

• PMID: 32937200
 
• DOI: 10.1016/j.prevetmed.2020.105128

Abstract

Details of incident cases of porcine reproductive and respiratory syndrome (PRRS) in United States breeding herds were obtained from the Morrison's Swine Health Monitoring Project. Herds were classified as cases if they reported an outbreak in a given season of the year and non-cases if they reported it in a season other than the case season or if they did not report a PRRS outbreak in any season. The geographic distribution of cases and non-cases was compared in each season of the year. The density of farms that had a PRRS outbreak during summer was higher in Southern Minnesota and Northwest-central Iowa compared to the density of the underlying population of non-case farms. This does not mean that PRRS outbreaks are more frequent during summer in absolute terms, but that there was a geographical clustering of herds breaking during summer in this area. Similar findings were observed in autumn. In addition, the density of farms reporting spring outbreaks was higher in the Southeast of the United States compared to that of the underlying population of non-case farms. A similar geographical clustering of PRRS outbreaks was observed during winter in the Southeast of the United States. Multivariable analyses, adjusting for the effect of known confounders, showed that the incidence rate of PRRS was significantly lower during winter and autumn during the porcine epidemic diarrhea (PED) epidemic years (2013-2014), compared to PRRS incidence rates observed during the winter and autumn of PED pre-epidemic years (2009-2012). After 2014, an increase in the incidence rate of PRRS was observed during winter and spring but not during autumn or summer. Pig dense areas were associated with a higher incidence rate throughout the year. However, this association tended to be stronger during the summer. Additionally, herds with ≥2500 sows had an increased incidence rate during all seasons except spring compared to those with <2500 sows. PRRS incidence was lower in year-round air-filtered herds compared to non-filtered herds throughout the year. We showed that not only the spatial risk of PRRS varies regionally according to the season of the year, but also that the effect of swine density, herd size and air filtering on PRRS incidence may also vary according to the season of the year. Further studies should investigate regional and seasonal drivers of disease. Breeding herds should maintain high biosecurity standards throughout the year.

Keywords: Factors; Incidence; PRRS; Risk; Sow; Spatial.

 Porcine Health Manag

. 2021 Apr 12;7(1):31.

 doi: 10.1186/s40813-021-00210-5.

Longitudinal piglet sampling in commercial sow farms highlights the challenge of PRRSV detection

Marcelo Nunes de Almeida 1, Cesar A Corzo 2, Jeffrey J Zimmerman 3, Daniel Correia Lima Linhares 3

Affiliations 

Affiliations

• 1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1811 Veterinary Medicine Annex, 1856 Christensen Dr. Ames, Ames, Iowa, 50011, USA. malmeida@iastate.ed.
• 2Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
• 3Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1811 Veterinary Medicine Annex, 1856 Christensen Dr. Ames, Ames, Iowa, 50011, USA.

• PMID: 33845917
 
• DOI: 10.1186/s40813-021-00210-5

Free article

Abstract

Background: Processing fluids (PF) and family oral fluids (FOF) are population-based surveillance samples collected from 2- to 5-day-old piglets and due-to-wean piglets, respectively. Although they are described for the surveillance of PRRSV in sows and piglet populations at processing and weaning, there is limited information on their use in commercial herds. This observational study described PRRSV RNA detection over time in PF, FOF, and piglet serum collected from farrowing groups in commercial breeding farms with the objective of achieving robust, practical, and effective PRRSV surveillance protocols. Weekly PF (an aggregate sample of all litters processed in a week from each room), and FOF (a convenience sample attempted from at least 20 individual litters in at least one farrowing room each week) samples were collected from six PRRSV-endemic commercial breeding herds for up to 38 weeks. A total of 561 PF room samples, 2400 individual litter FOF samples, and 600 serum samples (120 pools of 5 samples) were collected during the study period and tested for PRRSV RNA. Data were evaluated for patterns of PRRSV RNA detection by specimen within farms over time.

Results: In particular, the detection of PRRSV was commonly sporadic over time within farms (weeks of PRRSV RNA negative results followed by one or more weeks of positive results); was often non-uniform within farms (negative and positive farrowing rooms at a given point in time); and PF and FOF testing results agreement was 75 and 80% at week and room level, respectively, demonstrating that both sampling methods could complement each other. Non-uniformity in PRRSV detection in rooms sampled within the same week and detection after ≥11 consecutive weeks of PRRSV negative PF and FOF results underline the challenge of consistently detecting the virus.

Conclusions: These results suggest that monitoring protocols for breeding herds attempting PRRSV control or elimination can use both PF and FOF to improve PRRSV detection in suckling pig populations.

Keywords: Family oral fluids; PRRSV; Processing fluids; Serum; Surveillance; Swine.