Modeling the spread of porcine reproductive and respiratory syndrome virus (PRRSV) in a swine population: transmission dynamics, immunity information, and optimal control strategies

Phoo-ngurn, Phithakdet; Kiataramkul, Chanakarn; Chamchod, Farida

doi:10.1186/s13662-019-2351-6

Cited by 13 publications

(9 citation statements)

References 21 publications

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“…The important contribution of the local transmission route in spreading PRRSV into sow, GDU and finisher farms was consistent with previous studies, which demonstrated that farms located close to infected sites were more likely to report PRRSV outbreaks (Velasova et al, 2012; Phoo-ngurn et al, 2019; Silva et al, 2019; Jara et al, 2020), while others suggested that contact networks was the preferred transmission route (Amirpour Haredasht et al, 2017; Lee et al, 2017; Bastard et al, 2020; VanderWaal et al, 2020). Our approach to model the local PRRSV spread was unique in that we considered the effect of vegetation around each farm location as a physical barrier against mainly airborne transmission (Van Ryswyk et al, 2019; Jara et al, 2020).…”

Section: Discussionsupporting

confidence: 89%

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: Discussionsupporting

confidence: 89%

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

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“…The important contribution of the local transmission route in spreading PRRSV into sow, GDU and finisher farms was consistent with previous studies, which demonstrated that farms located close to infected sites were more likely to report PRRSV outbreaks (Jara et al, 2020;Phoo-ngurn et al, 2019;Silva et al, 2019;Velasova et al, 2012). Similarly, our result highlighted the importance of transmission by direct contact through pig movements, as pointed out by other studies (Amirpour Haredasht et al, 2017;Lee et al, 2017;VanderWaal et al, 2020).…”

Section: Contribution Of Transmission Routessupporting

confidence: 93%

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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“…Our model results also demonstrate that the success of combined control strategies hinges on their relative effectiveness. Whereas evidence to date suggests that pigs carrying two copies of the PRRS resistance alleles are fully resistant to PRRSV infection (i.e., effectiveness of gene editing = 1) ( 27 , 28 , 46 ), the effectiveness of existing PRRS vaccines is severely compromised among other factors by the limited cross-protectivity of a given vaccine to different PRRSV strains, resulting in vaccine efficacies below 50% ( 47 , 48 ), suboptimal vaccine administration ( 37 , 49 ), or host heterogeneity in vaccine responsiveness ( 50 ). In our model, elimination of PRRS falls out of reach for the less stringent unregulated and concentrated distribution scenarios if vaccine effectiveness drops below 50%.…”

Section: Discussionmentioning

confidence: 99%

Modeling suggests gene editing combined with vaccination could eliminate a persistent disease in livestock

Petersen¹,

Buntjer

Fs³

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Recent breakthroughs in gene-editing technologies that can render individual animals fully resistant to infections may offer unprecedented opportunities for controlling future epidemics in farm animals. Yet, their potential for reducing disease spread is poorly understood as the necessary theoretical framework for estimating epidemiological effects arising from gene-editing applications is currently lacking. Here, we develop semistochastic modeling approaches to investigate how the adoption of gene editing may affect infectious disease prevalence in farmed animal populations and the prospects and time scale for disease elimination. We apply our models to the porcine reproductive and respiratory syndrome (PRRS), one of the most persistent global livestock diseases to date. Whereas extensive control efforts have shown limited success, recent production of gene-edited pigs that are fully resistant to the PRRS virus have raised expectations for eliminating this deadly disease. Our models predict that disease elimination on a national scale would be difficult to achieve if gene editing was used as the only disease control. However, from a purely epidemiological perspective, disease elimination may be achievable within 3 to 6 y, if gene editing were complemented with widespread and sufficiently effective vaccination. Besides strategic distribution of genetically resistant animals, several other key determinants underpinning the epidemiological impact of gene editing were identified.

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Modeling the spread of porcine reproductive and respiratory syndrome virus (PRRSV) in a swine population: transmission dynamics, immunity information, and optimal control strategies

Cited by 13 publications

References 21 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

Modeling suggests gene editing combined with vaccination could eliminate a persistent disease in livestock

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