Friday, March 23, 2018

Modelling economic efficiency of strategies to control PRRS

 2018 Apr 1;152:89-102. doi: 10.1016/j.prevetmed.2018.02.005. Epub 2018 Feb 9.

Modelling the economic efficiency of using different strategies to control Porcine Reproductive & Respiratory Syndrome at herd level.

Author information

1
Clinic for Swine, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Switzerland.
2
Veterinary Epidemiology, Economics and Public Health Group, Department of Production and Population Health, Royal Veterinary College of London, United Kingdom.
3
Merck Animal Health, NJ, United States.
4
MSD Animal Health, Germany.
5
MSD Animal Health, The Netherlands.
6
MSD Animal Health, Spain.
7
Veterinary Public Health Institute, Department of Clinical Research & Veterinary Public Health, Vetsuisse Faculty, University of Bern, Switzerland. Electronic address: christina.nathues@blv.admin.ch.

Abstract

PRRS is among the diseases with the highest economic impact in pig production worldwide. Different strategies have been developed and applied to combat PRRS at farm level. The broad variety of available intervention strategies makes it difficult to decide on the most cost-efficient strategy for a given farm situation, as it depends on many farm-individual factors like disease severity, prices or farm structure. Aim of this study was to create a simulation tool to estimate the cost-efficiency of different control strategies at individual farm level. Baseline is a model that estimates the costs of PRRS, based on changes in health and productivity, in a specific farm setting (e.g. farm type, herd size, type of batch farrowing). The model evaluates different intervention scenarios: depopulation/repopulation (D/R), close & roll-over (C&R), mass vaccination of sows (MS), mass vaccination of sows and vaccination of piglets (MS + piglets), improvements in internal biosecurity (BSM), and combinations of vaccinations with BSM. Data on improvement in health and productivity parameters for each intervention were obtained through literature review and from expert opinions. The economic efficiency of the different strategies was assessed over 5 years through investment appraisals: the resulting expected value (EV) indicated the most cost-effective strategy. Calculations were performed for 5 example scenarios with varying farm type (farrow-to-finish - breeding herd), disease severity (slightly - moderately - severely affected) and PRRSV detection (yes - no). The assumed herd size was 1000 sows with farm and price structure as commonly found in Germany. In a moderately affected (moderate deviations in health and productivity parameters from what could be expected in an average negative herd), unstable farrow-to-finish herd, the most cost-efficient strategies according to their median EV were C&R (€1'126'807) and MS + piglets (€ 1'114'649). In a slightly affected farrow-to-finish herd, no virus detected, the highest median EV was for MS + piglets (€ 721'745) and MS (€ 664'111). Results indicate that the expected benefits of interventions and the most efficient strategy depend on the individual farm situation, e.g. disease severity. The model provides new insights regarding the cost-efficiency of various PRRSV intervention strategies at farm level. It is a valuable tool for farmers and veterinarians to estimate expected economic consequences of an intervention for a specific farm setting and thus enables a better informed decision.

KEYWORDS: 

Cost of interventions; Economic modelling; Farm-level measures; PRRS control; PRRSV epidemiology
PMID:
 
29559110
 
DOI:
 
10.1016/j.prevetmed.2018.02.005

Saturday, March 17, 2018

Effect of vaccination with a PRRSV subunit vaccine on sow reproductive performance in endemic farms in South Korea.

 2018 Mar 15. pii: vetrec-2017-104547. doi: 10.1136/vr.104547. [Epub ahead of print]

Effect of vaccination with a porcine reproductive and respiratory syndrome subunit vaccine on sow reproductive performance in endemic farms.

Author information

1
Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea.
2
College of Liberal Arts, Anyang University, Anyang, Republic of Korea.

Abstract

The objective of this field study was to evaluate the reproductive performance of sows after vaccination with a porcine reproductive and respiratory syndrome (PRRS) subunit vaccine (PRRSFREE PRRS subunit vaccine, Reber Genetics, Taiwan, Republic of China) under field conditions. The study was performed in three farms with endemic infections with both PRRS virus (PRRSV)-1 and PRRSV-2, a situation representative of most Korean farms. Pregnant sows were immunised intramuscularly with 2.0 ml of the PRRS subunit vaccine at 58 and 79 days of gestation (eight and five weeks antepartum) according to the manufacturer's recommendation. Vaccination did not result in any observed adverse reaction. Vaccinated sows exhibited a significant improvement in reproductive performance (reduction of abortions) and litter characteristics (increase of weaned pigs) compared with unvaccinated sows. Vaccinated sows had significantly (P<0.05) higher PRRSV ELISA sample/positive ratio and number of PRRSV-specific interferon-γ-secreting cells compared with the unvaccinated control group. The results of this study demonstrate that the PRRS subunit vaccine can improve the reproductive performance of sows in farms with endemic PRRSV infection.

KEYWORDS: 

porcine reproductive and respiratory syndrome (prrs); reproductive failure; sow; vaccine
PMID:
 
29545353
 
DOI:
 
10.1136/vr.104547

Friday, March 16, 2018

Unraveling the contact patterns and network structure of pig shipments in the US and its association with PRRS outbreaks

 2017 Mar 1;138:113-123. doi: 10.1016/j.prevetmed.2017.02.001. Epub 2017 Feb 2.

Unraveling the contact patterns and network structure of pig shipments in the United States and its association with porcine reproductive and respiratory syndrome virus (PRRSV) outbreaks.

Author information

1
Center for Animal Disease Modeling and Surveillance (CADMS), Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, USA. Electronic address: pvmlee@ucdavis.edu.
2
Boehringer - Ingelheim Vetmedica, Inc., St. Joseph, MO, USA.
3
Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
4
Center for Animal Disease Modeling and Surveillance (CADMS), Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, USA.

Abstract

The analysis of the pork value chain is becoming key to understanding the risk of infectious disease dissemination in the swine industry. In this study, we used social network analysis to characterize the swine shipment network structure and properties in a typical multisite swine production system in the US. We also aimed to evaluate the association between network properties and porcine respiratory and reproductive syndrome virus (PRRSV) transmission between production sites. We analyzed the 109,868 swine shipments transporting over 93 million swine between more than 500 production sites from 2012 to 2014. A total of 248 PRRSV positive occurrences were reported from 79 production sites during those 3 years. The temporal dynamics of swine shipments was evaluated by computing network properties in one-month and three-month networks. The association of PRRS occurrence in sow farms with centrality properties from one-month and three-month networks was assessed by using the multilevel logistic regression. All monthly networks showed a scale-free network topology with positive degree assortativity. The regression model revealed that out-degree centrality had a negative association with PRRS occurrence in sow farms in both one-month and three-month networks [OR=0.79 (95% CI, 0.63-0.99) in one-month network and 0.56 (95% CI, 0.36, 0.88) in three-month network] and in-closeness centrality model was positively associated with PRRS occurrence in sow farms in the three-month network [OR=2.45 (95% CI, 1.14-5.26)]. We also describe how the occurrence of porcine epidemic diarrheac (PED) outbreaks severely affected the network structure as well as the PRRS occurrence reports and its association with centrality measures in sow farms. The structure of the swine shipment network and the connectivity between production sites influenced on the PRRSV transmission. The use of network topology and characteristics combining with spatial analysis based on fine scale geographical location of production sites will be useful to inform the design of more cost-efficient, risk-based surveillance and control measures for PRRSV as well as other diseases in the US swine industry.

KEYWORDS: 

Infectious disease; PED; PRRS; Pork value chain; Social network analysis; Swine
PMID:
 
28237226
 
DOI:
 
10.1016/j.prevetmed.2017.02.001
[Indexed for MEDLINE]

Transmission parameters for IAV and PRRSV in pigs from weaning to slaughter under natural conditions

 2017 Mar 1;138:147-155. doi: 10.1016/j.prevetmed.2017.01.008. Epub 2017 Jan 18.

Estimation of the transmission parameters for swine influenza and porcine reproductive and respiratory syndrome viruses in pigs from weaning to slaughter under natural conditions.

Author information

1
IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain,; Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain.
2
IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain,; Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain. Electronic address: g.e.martinvalls@gmail.com.
3
IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
4
IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain,; Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain. Electronic address: alberto.allepuz@uab.es.

Abstract

In the present study, the transmission parameters of swine influenza virus (SIV) and porcine reproductive and respiratory virus (PRRSV) have been calculated using the basic reproductive rate (R) parameter in two commercial pig farms (F1 and F2). In order to do this, a serological (PRRSV genotype 1 and SIV) and virological (SIV) follow-up of a batch of animals was carried out weekly from 3 weeks of age until the age of slaughter on each farm. Results of the analysis for SIV and PRRSV showed different transmission profiles depending on the farm, the pathogen, and time of transmission. In F1, transmission of both viruses was detected throughout the sampling. The Rt (R for a given period of time) value for SIV ranged from 1.5 [0.9-2.3] to 3.6 [2.3-4.9] from farrowing to the beginning of the fattening period, and the Rt value for PRRSV was 3.3 [2.9-4.3] to 3.5 [2.8-4.1] from farrowing until the slaughter age. These results indicated that both viruses were transmitted enzootically in that farm for these periods of time. A different transmission pattern with a higher incidence was also observed during the fattening period in F1 (after 15 weeks of age) for SIV, coinciding with the entrance of a new subtype. In this case, R value for SIV reached 3.3 [1.65-4.9]. On the other hand, in F2, SIV and PRRSV seemed to be restricted to the fattening period. R reached a value of 6.4 [4.1-8.8] for SIV and 7.1 [3.5-10.6] for PRRSV. These findings suggest a different origin of the virus, as well as a more epidemic circulation, especially for SIV, where most of the new cases were observed in a one week period. In conclusion, the present study offers a reliable estimation of the range of Rt values for SIV and genotype 1 PRRSV transmission under field conditions, suggesting that enzootic circulations of both viruses are similar in terms of transmission, probably higher for PRRSV, but also that transmission of SIV is more efficient (or epidemic) than transmission of a genotype 1 PRRSV isolate in naïve animals given the new cases observed in only in F2.

KEYWORDS: 

Basic reproductive rate; PRRSV; SIV; Transmission rate
PMID:
 
28237230
 
DOI:
 
10.1016/j.prevetmed.2017.01.008
[Indexed for MEDLINE]