1
|
Sanhueza JM, Schwartz M, Corzo CA, Kikuti M, Yeske P, Leuwerke B, Schelkopf A, Williams T, Feuerbach S, Johnson C, Toohill E, Tapia-Escarate D, Yang M, Schroeder D, Vilalta C. Assessing the role of sow parity on PRRSv detection by RT-qPCR through weekly processing fluids monitoring in breeding herds. Prev Vet Med 2023; 213:105854. [PMID: 36758300 DOI: 10.1016/j.prevetmed.2023.105854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 12/18/2022] [Accepted: 01/21/2023] [Indexed: 01/25/2023]
Abstract
The use of processing fluids to monitor the breeding herd's porcine reproductive and respiratory syndrome (PRRS) status has gained industry acceptance. However, little is known about PRRS virus RT-qPCR detection dynamics in processing fluids and factors that may contribute to maintain PRRS virus in the herd after an outbreak. This study aimed to describe weekly RT-qPCR processing fluid results in breeding herds after an outbreak and to evaluate the proportion of RT-qPCR positive results among parity groups. Processing tissues of 15 first parity (P1), 15 second parity (P2), and 15 third parity or higher (P3+) litters (parity groups) were collected weekly for between 19 and 46 weeks in nine breeding herds. Processing fluids were aggregated, and RT-qPCR tested by parity group weekly. Additionally, a subset of 743 processing fluid samples of litters that formed 50 parity groups, as previously described, were RT-qPCR tested individually at the litter level. The agreement between RT-qPCR results of processing fluid samples of parity groups (15 litters) and results based on individual litter testing was assessed using overall percent of agreement, Kappa statistic, and McNemar test. The association between RT-qPCR results and the parity group was evaluated using a generalized estimating equations model, after accounting for the effects of sampling week, breeding herd PRRS control strategy (i.e., open to replacements v/s closed) and herd. An autoregressive correlation structure was used to account for the repeated samplings within a herd in time. The overall agreement was 98 %, and Kappa statistic 0.955 (McNemar p = 1.0). Sensitivity of parity group processing fluid samples was estimated at 100 % (95 % CI 89-100 %), while specificity was estimated at 94 % (95 % CI 71-100 %). Although P1 aggregated litters had on average a higher proportion of RT-qPCR positive results from outbreak week 25 onwards, the proportion was not significantly different to the one observed for P2 and P3+ aggregated litters (p > 0.13). Additionally, herds that interrupted gilt entry had lower odds of PRRS RT-qPCR positivity than herds that continued entering gilts (OR = 0.35, 95 % CI 0.16-0.78). PRRS virus persistence in processing fluids was not affected by the sow parity effect in most of the breeding herds studied. No evidence of disagreement between RT-qPCR results of an aggregated sample of 15 litters and those of individual litters was observed. This level of litter aggregation testing strategy may be of particular use at the last stages of an elimination program under low PRRS virus prevalence.
Collapse
Affiliation(s)
- Juan Manuel Sanhueza
- Departamento de Ciencias Veterinarias y Salud Pública, Facultad de Recursos Naturales, Universidad Católica de Temuco, Chile.
| | | | - Cesar A Corzo
- Population Medicine Department, University of Minnesota, United States of America
| | - Mariana Kikuti
- Population Medicine Department, University of Minnesota, United States of America
| | - Paul Yeske
- Swine Vet Center, Saint Peter, MN, United States of America
| | - Brad Leuwerke
- Swine Vet Center, Saint Peter, MN, United States of America
| | - Adam Schelkopf
- Pipestone Veterinary Services, Pipestone, MN, United States of America
| | - Todd Williams
- Pipestone Veterinary Services, Pipestone, MN, United States of America
| | - Steven Feuerbach
- Pipestone Veterinary Services, Pipestone, MN, United States of America
| | - Clayton Johnson
- Carthage Veterinary Service, Ltd., Carthage, IL, United States of America
| | - Elise Toohill
- Carthage Veterinary Service, Ltd., Carthage, IL, United States of America
| | - Daniela Tapia-Escarate
- Departamento de Ciencias Veterinarias y Salud Pública, Facultad de Recursos Naturales, Universidad Católica de Temuco, Chile
| | - My Yang
- Population Medicine Department, University of Minnesota, United States of America
| | - Declan Schroeder
- Population Medicine Department, University of Minnesota, United States of America
| | - Carles Vilalta
- Unitat mixta d'Investigació IRTA-UAB en Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), Bellaterra 08193, Catalonia, Spain; IRTA, Programa de Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), Bellaterra 08193, Catalonia, Spain
| |
Collapse
|
2
|
López WA, Gauger PC, Harmon KM, Holtkamp DJ, Cano JP, Macedo N, Zhang M, Silva GS, Angulo J, Zimmerman JJ, Linhares DCL. Probability of PRRS virus detection in pooled processing fluid samples. Vet Microbiol 2021; 261:109190. [PMID: 34411996 DOI: 10.1016/j.vetmic.2021.109190] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 07/30/2021] [Indexed: 11/17/2022]
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.
Collapse
Affiliation(s)
- Will A López
- 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
| | - Phillip C Gauger
- 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
| | - Karen M Harmon
- 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
| | - Derald J Holtkamp
- 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
| | - Jean Paul Cano
- 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; Pipestone Veterinary Services, 1300 US-75, Pipestone, MN 56164, United States
| | - Nubia Macedo
- 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
| | - Min Zhang
- Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, United States
| | - Gustavo S Silva
- 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
| | | | - Jeffrey J Zimmerman
- 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
| | - Daniel C L Linhares
- 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.
| |
Collapse
|
3
|
de Almeida MN, Corzo CA, Zimmerman JJ, Linhares DCL. Longitudinal piglet sampling in commercial sow farms highlights the challenge of PRRSV detection. Porcine Health Manag 2021; 7:31. [PMID: 33845917 PMCID: PMC8040214 DOI: 10.1186/s40813-021-00210-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 03/26/2021] [Indexed: 11/21/2022] Open
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.
Collapse
Affiliation(s)
- Marcelo Nunes de Almeida
- Department 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.
| | - Cesar A Corzo
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Jeffrey J Zimmerman
- Department 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
| | - Daniel Correia Lima Linhares
- Department 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
| |
Collapse
|
4
|
Vilalta C, Sanhueza JM, Schwartz M, Kikuti M, Torremorell M, Corzo CA. Assessing the litter level agreement of RT-PCR results for porcine reproductive and respiratory syndrome virus in testicles, tails and udder wipes diagnostic samples relative to serum from piglets. Prev Vet Med 2021; 186:105211. [PMID: 33310196 DOI: 10.1016/j.prevetmed.2020.105211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/11/2020] [Accepted: 11/15/2020] [Indexed: 11/20/2022]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) is currently the most detrimental disease in the U.S swine industry. Clinical signs of PRRS virus (PRRSv) infection in breeding herds include reproductive failure with abortions, stillbirths, premature farrowings and increased pre-weaning mortality. Serum from due-to-wean piglets is considered the most suitable specimen to monitor PRRSv infection and stability in breeding herds. However, processing fluids (PF - the serosanguinous exudate resultant of the collection of tails and testicles during processing) are a new specimen proposed to monitor piglets at processing (3-5 days of age) and udder wipes (UW) of lactating sows is yet another specimen to monitor infection status of suckling piglets indirectly. Here, we assessed which specimen type (e.g. sera, testicles, tails or UW) should be used to accurately establish the PRRSv status of a litter. Twenty-four litters were conveniently selected on a farm at 10 weeks post PRRSv outbreak. Blood samples, tails and testicles from every piglet in a litter, and an udder skin wipe from the sow were collected at processing (3-5 days). Individual litter testicles and tails as well as the udder wipe were placed each in a reclosable bag to prevent cross-contamination. Sensitivity (Se), specificity (Sp), negative predictive value (NPV), positive predictive value (PPV) and global agreement at the litter level were calculated using the sera results of the litter as the gold standard. The optimum cycle threshold (Ct) value to classify a sample as negative was ≥35 for serum and ≥36 for the aggregated samples (testicles, tails, and UW) based on the ROC curve analysis. Using those thresholds, the fluid collected from the testicles showed the best overall performance (Se = 92 % [62-100]; Sp = 82 % [48-98], NPV = 90 % [55-100], PPV = 85 % [55-98], global agreement = 87 %) compared to tail fluid and UW. Sensitivity of the tail fluid was 62 % (32-86) and the UW was 23 % (5-54), both of which yielded a 100 % specificity and PPV. This study provides information on the contribution of each of the tissues collected at processing on the detection of PRRSv, which becomes relevant in countries were castration and/or tail docking is banned.
Collapse
|
5
|
López WA, Zimmerman JJ, Gauger PC, Harmon KM, Bradner L, Zhang M, Giménez-Lirola L, Ramirez A, Cano JP, Linhares DCL. Practical aspects of PRRSV RNA detection in processing fluids collected in commercial swine farms. Prev Vet Med 2020; 180:105021. [PMID: 32428814 DOI: 10.1016/j.prevetmed.2020.105021] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/22/2020] [Accepted: 04/24/2020] [Indexed: 11/29/2022]
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.
Collapse
Affiliation(s)
- Will A López
- 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
| | - Jeffrey J Zimmerman
- 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
| | - Phillip C Gauger
- 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
| | - Karen M Harmon
- 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
| | - Laura Bradner
- 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
| | - Min Zhang
- Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, Iowa 50011, United States
| | - Luis Giménez-Lirola
- 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
| | - Alejandro Ramirez
- 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
| | - Jean Paul Cano
- 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
| | - Daniel C L Linhares
- 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.
| |
Collapse
|
6
|
Vilalta C, Sanhueza J, Alvarez J, Murray D, Torremorell M, Corzo C, Morrison R. Use of processing fluids and serum samples to characterize porcine reproductive and respiratory syndrome virus dynamics in 3 day-old pigs. Vet Microbiol 2018; 225:149-156. [PMID: 30293648 DOI: 10.1016/j.vetmic.2018.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 09/12/2018] [Accepted: 09/13/2018] [Indexed: 12/12/2022]
Abstract
Collection of serum samples of pigs at weaning to monitor for porcine reproductive and respiratory syndrome virus (PRRSV) has become a common practice to determine PRRSV herd infection status. Diagnostic sensitivity of this practice is low in herds undergoing PRRSV elimination once prevalence of infection is near zero. Thus, the goal of this study was to characterize the dynamics of PRRSV infection in 3 day-old pigs overtime using serum and serosanguineous fluids obtained as part of castration and tail docking practices (processing fluids (PF)). Secondary goal was to estimate sensitivity and specificity of PF in the 3 day old population. A 6000 breed-to-wean sow herd was monitored every three weeks for 23 weeks after a PRRSV outbreak by collecting both PF and individual serum samples from all pigs in the selected litters. Out of the 77 litters tested, 23 (29.8%) were identified as positive using the PF and the serum samples, with a Cohen's kappa statistic of 0.81 (95% CI: 0.59-1) between the results obtained in each sample type. The sensitivity and specificity of the PF relative to the results in serum was 87% (95% CI: 66%-97%) and 94% (95% CI: 85%-99%) respectively. The percentage of PRRSV positive litters decreased over time and litters from gilts were more likely to test positive than those from older sows. Overall, the study demonstrates that PF can be a convenient and reliable specimen to monitor PRRSV infection in breeding herds.
Collapse
Affiliation(s)
- Carles Vilalta
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave., St Paul, MN 55108, United States.
| | - Juan Sanhueza
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave., St Paul, MN 55108, United States
| | - Julio Alvarez
- VISAVET Health Surveillance Center, Universidad Complutense, Avda Puerta de Hierro S/N, Madrid, 28040, Spain; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense, Avda Puerta de Hierro S/N, Madrid, 28040, Spain
| | - Deb Murray
- New Fashion Pork, Jackson, MN, United States
| | - Montserrat Torremorell
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave., St Paul, MN 55108, United States
| | - Cesar Corzo
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave., St Paul, MN 55108, United States
| | - Robert Morrison
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave., St Paul, MN 55108, United States
| |
Collapse
|