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

Henao-Díaz, Alexandra; Ji, Ju; Giménez-Lirola, Luis; Baum, David H.; Zimmerman, Jeffrey J.

doi:10.1016/j.rvsc.2020.04.023

Cited by 18 publications

(15 citation statements)

References 24 publications

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“…Similarly, prophylactic #2 was highly efficient to prevent infection in finisher farms, and implement vaccination within one week of placement was the best complementary strategy. We also showed that the control of PRRSV spread can be optimized if diagnostic in downstream farms is enhanced and if vaccination is deployed early on PRRSV infection (Henao-Diaz et al, 2020). Finally, based on our baseline model we present two mapping results, a forecasting map showing the most likely infected farms and a map showing at-risk locations in which the risk that PRRSV has been introduced within an average of four weeks was estimated to be high.…”

Section: Discussionmentioning

confidence: 99%

Modeling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

Galvis

Prada

Jones

et al. 2020

Preprint

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14 15 In the monitoring of porcine reproductive and respiratory syndrome virus (PRRSv), 16 knowledge about between-farm transmission dynamics is still lacking. Our objective was 17 to assess the relative contribution of between-farm PRRSv transmission routes through a 18 mechanistic epidemiological model calibrated with PRRSv occurrence, identify risk 19 areas, and estimate the impact of immunization strategies in the disease spread. We 20 developed a mathematical model of PRRSv transmission accounting for spatial 21 proximity, pig movements, and re-breaks in sow farms, parametrized on data collected 22 routinely by commercial pig farms. We then used the model to simulate the weekly 23 frequency of cases and built risk maps, and compared with the observed cases. We 24 simulated the implementation of two immunization strategies (preventive and reactive) to 25 mitigate the between-farm transmission. Our results indicated for sow and GDU farms' 26 local spread on average was above 60%, while for nurseries between-farm movements 27 represented 83% of transmissions and in finisher farms it was distributed almost 50% 28 local and 50% between-farm movement, the model allowed reproduce the weekly 29 frequency of observed cases and the risk maps built allowed the identification of 30 observed cases in the space. The increase in vaccine efficacy was the most important 31 parameter to mitigate between-farm transmission. Also, the implementation of 32 immunization by a preventive and reactive strategy combined had the better result to 33 mitigate between-farm transmission than implement these strategies individually. These 34 immunization strategies had a better performance with the use of rigorous protocols, such 35

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Section: Discussionmentioning

confidence: 99%

Modeling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

Galvis

Prada

Jones

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Similarly, prophylactic #2 was highly efficient to prevent infection in finisher farms, and implement vaccination within 1 week of placement was the best complementary strategy. We also showed that the control of PRRSV spread can be optimized if diagnostic in downstream farms is enhanced and if vaccination is deployed early on PRRSV infection (Henao‐Diaz et al., 2020). Finally, based on our baseline model we present two mapping results, a forecasting map showing the most likely infected farms and a map showing at‐risk locations in which the risk that PRRSV has been introduced within an average of 4 weeks was estimated to be high.…”

Section: Discussionmentioning

confidence: 99%

Modelling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

Galvis¹,

Corzo

Prada

et al. 2021

Transbounding Emerging Dis

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Many aspects of the porcine reproductive and respiratory syndrome virus (PRRSV) between‐farm transmission dynamics have been investigated, but uncertainty remains about the significance of farm type and different transmission routes on PRRSV spread. We developed a stochastic epidemiological model calibrated on weekly PRRSV outbreaks accounting for the population dynamics in different pig production phases, breeding herds, gilt development units, nurseries and finisher farms, of three hog producer companies. Our model accounted for indirect contacts by the close distance between farms (local transmission), between‐farm animal movements (pig flow) and reinfection of sow farms (re‐break). The fitted model was used to examine the effectiveness of vaccination strategies and complementary interventions such as enhanced PRRSV detection and vaccination delays and forecast the spatial distribution of PRRSV outbreak. The results of our analysis indicated that for sow farms, 59% of the simulated infections were related to local transmission (e.g. airborne, feed deliveries, shared equipment) whereas 36% and 5% were related to animal movements and re‐break, respectively. For nursery farms, 80% of infections were related to animal movements and 20% to local transmission; while at finisher farms, it was split between local transmission and animal movements. Assuming that the current vaccines are 1% effective in mitigating between‐farm PRRSV transmission, weaned pigs vaccination would reduce the incidence of PRRSV outbreaks by 3%, indeed under any scenario vaccination alone was insufficient for completely controlling PRRSV spread. Our results also showed that intensifying PRRSV detection and/or vaccination pigs at placement increased the effectiveness of all simulated vaccination strategies. Our model reproduced the incidence and PRRSV spatial distribution; therefore, this model could also be used to map current and future farms at‐risk. Finally, this model could be a useful tool for veterinarians, allowing them to identify the effect of transmission routes and different vaccination interventions to control PRRSV spread.

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“…Recently, tonsil scraping (TS) has been described as a promising diagnostic specimen for growing pig populations ( 16 ). A recent study utilizing tonsil scraping samples for RT-PCR and bioassays has shown up to 77% detection rate ( 17 ), while another study found no difference among the efficacy of tonsil scrapings, blood, and oral fluids at 70-, 96- and 118-days post infection using RT-PCR ( 18 ).…”

Section: Introductionmentioning

confidence: 99%

Detection of Multiple Lineages of PRRSV in Breeding and Growing Swine Farms

et al. 2022

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The detection and co-circulation of multiple variants of porcine reproductive and respiratory syndrome virus (PRRSV) have been observed and reported in swine. However, the potential long-term impact of multiple prevailing PRRSV variants on pig-performance is not yet fully understood. The primary objective of this study was to describe the genetic variation of PRRSV in processing fluid (PF), oral fluid (OF), and tonsil scraping (TS) specimens from five swine farms with different production types and PRRS status over a period of time (~1 year). Furthermore, the association between PRRSV prevalence and production parameters was investigated. Results showed that PRRSV was detected by RT-qPCR in 21–25% of all types of specimens. In breeding farms, PRRSV detection in PF and/or TS samples was correlated with stillborn and mummified fetuses, and pre-weaning mortality throughout the study period. Although ORF5 sequences were obtained in <16% of all sample types, simultaneous detection of PRRSV variants including field and vaccine strains within a single sampling event was identified in both breeding and growing pig farms. Phylogenetic analyses based on the ORF5 sequence classified the detected field PRRSV into L1A and L1H, two sub-lineages of lineage 1 (L1). Our study demonstrated the presence of multiple PRRSV lineages, sub-lineages, and variants in swine herds and its potential association with swine reproductive performance under field conditions.

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

Cited by 18 publications

References 24 publications

Modeling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

Modeling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

Modelling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

Detection of Multiple Lineages of PRRSV in Breeding and Growing Swine Farms

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