Thursday, June 21, 2018

Production losses associated with PRRS in US sow farms

 2018 May 16;5:102. doi: 10.3389/fvets.2018.00102. eCollection 2018.

Production Losses From an Endemic Animal Disease: Porcine Reproductive and Respiratory Syndrome (PRRS) in Selected Midwest US Sow Farms.

Author information

1
Department of Agricultural and Resource Economics, University of California Davis, Davis, CA, United States.
2
Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, United States.
3
Center for Animal Health and Food Safety, University of Minnesota, St. Paul, MN, United States.

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is an endemic disease causing important economic losses to the US swine industry. The complex epidemiology of the disease, along with the diverse clinical outputs observed in different types of infected farms, have hampered efforts to quantify PRRS' impact on production over time. We measured the impact of PRRS on the production of weaned pigs using a log-linear fixed effects model to evaluate longitudinal data collected from 16 sow farms belonging to a specific firm. We measured seven additional indicators of farm performance to gain insight into disease dynamics. We used pre-outbreak longitudinal data to establish a baseline that was then used to estimate the decrease in production. A significant rise of abortions in the week before the outbreak was reported was the strongest signal of PRRSV activity. In addition, production declined slightly one week before the outbreak and then fell markedly until weeks 5 and 6 post-outbreak. Recovery was not monotonic, cycling gently around a rising trend. At the end of the study period (35 weeks post-outbreak), neither the production of weaned pigs nor any of the performance indicators had fully recovered to baseline levels. This result suggests PRSS outbreaks may last longer than has been found in most other studies. We assessed PRRS' effect on farm efficiency as measured by changes in sow production of weaned pigs per year. We translated production losses into revenue losses assuming an average market price of $45.2/weaned pig. We estimate that the average PRSS outbreak reduced production by approximately 7.4%, relative to annual output in the absence of an outbreak. PRRS reduced production by 1.92 weaned pigs per sow when adjusted to an annual basis. This decrease is substantially larger than the 1.44 decrease of weaned pigs per sow/year reported elsewhere.

KEYWORDS: 

Endemic Animal Disease; Fixed effects model ; Porcine Reproductive and Respiratory Syndrome; Production Impacts; Sow Farms; US Swine Industry
PMID:
 
29922683
 
PMCID:
 
PMC5996871
 
DOI:
 
10.3389/fvets.2018.00102

Wednesday, May 30, 2018

Comparative evaluation of immune responses of swine in PRRS-stable and unstable herds


 2018 Jun;200:32-39. doi: 10.1016/j.vetimm.2018.04.007. Epub 2018 Apr 22.

Comparative evaluation of immune responses of swine in PRRS-stable and unstable herds.

Author information

1
Department of Animal Medicine, Production and Health, Veterinary Padua University, Viale dell'Università 16-Agripolis, 35020 Legnaro, PD, Italy.
2
Diagnostic Laboratory, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, via A. Bianchi 9, 25124 Brescia, Italy.
3
Laboratory of Cellular Immunology, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, via A. Bianchi 9, 25124 Brescia, Italy.
4
Genomics Department, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, via A. Bianchi 9, 25124 Brescia, Italy.
5
Laboratory of Cellular Immunology, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, via A. Bianchi 9, 25124 Brescia, Italy. Electronic address: massimo.amadori@izsler.it.

Abstract

Porcine Reproductive and Respiratory Syndrome (PRRS) is an elusive model of host/virus relationship in which disease is determined by virus pathogenicity, pig breed susceptibility and phenotype, microbial infectious pressure and environmental conditions. Successful disease control in PRRS-endemic Countries corresponds to "stability", i.e. a condition with no clinical signs of PRRS in the breeding-herd population and no viremia in weaning-age pigs. The aim of this work was to compare the profile and time-course of humoral and cell-mediated immunity in stable and unstable herds, respectively. In particular, we investigated PRRS virus (PRRSV) in serum and group oral fluid samples by Real-time RT-PCR, PRRSV-specific IgA and IgG in oral fluids, serum IgG antibody and the cell-mediated response (PRRSV-specific release of interferon-gamma) in whole blood samples. These parameters were measured in order to identify possible discrepancies in the development and kinetics of the immune response against PRRSV. PRRS-free gilts got regularly infected after entering PRRS-stable and unstable farms. In an open cycle, unstable pig farm PRRSV infection could be demonstrated in all groups of pigs, including suckling piglets. Four main results should be highlighted: A) the precocity of the Ab response in group oral fluids was generally similar to that recorded in sera; B) circulation of PRRSV was consistently detected in all age groups in the unstable herds, as opposed to the stable ones; C) an early, balanced, IgA and IgG response in oral fluids was only observed in the stable herds; D) an early IFN-gamma response after PRRSV infection was often observed in stable herds, as opposed to the unstable ones. These were characterized by IFN-gamma responses in piglets, likely due to transfer of maternal immunity. Most important, the mucosal IgA response was associated with cessation of virus excretion in oral fluid samples of PRRS-unstable herds. The above findings indicate that a peculiar profile of immune response to PRRSV can be found in PRRS-stable herds. Therefore, the outlined immune parameters can represent a useful readout system to evaluate successful adaptation to PRRSV based on acclimatization of breeding animals and management of pig flow.

KEYWORDS: 

Cell-mediated immunity; Herd; Mucosal immunity; PRRS; Pig; Stability
PMID:
 
29776610
 
DOI:
 
10.1016/j.vetimm.2018.04.007

Thursday, April 26, 2018

Susceptibility to PRRSV infection among Chinese native pig breeds

 2018 Apr 24. doi: 10.1007/s00705-018-3821-y. [Epub ahead of print]

Different susceptibility to porcine reproductive and respiratory syndrome virus infection among Chinese native pig breeds.

Meng C1,2Su L1,3Li Y1,2Zhu Q3Li J3Wang H1,2He Q1Wang C3Wang W3Cao S4,5,6.

Abstract

China is rich in native pig breeds, yet information regarding the susceptibility/resistance of local breeds to porcine reproductive and respiratory syndrome virus (PRRSV) infection is lacking. In the present study, an in vitro method based on assessing PRRSV replication in porcine alveolar macrophages (PAMs) was established to evaluate PRRSV susceptibility/resistance in a commercial pig breed (Landrace) and five native pig breeds from Jiangsu and Anhui provinces in China. Expression levels of cytokines (IL-8, IL-10, TNF-α and IFN-γ), Toll-like receptor 3 (TLR3), CD163 (PRRSV receptor), and sialoadhesin (Sn, PRRSV receptor) in infected pigs were determined using real-time PCR, and the association between PRRSV susceptibility/resistance and the abundance of the cytokines and receptors was investigated. The viral replication rate and titer at 0, 6, 12 18, 24 and 36 hours postinfection (hpi) were determined to assess the proliferation dynamics of PRRSV NJGC in PAMs. Based on the PRRSV proliferation dynamics, the results indicated that Dingyuan pigs were the most susceptible to PRRSV infection, whereas Jiangquhai pigs were the least susceptible to PRRSV infection among the six pig breeds tested, as indicated by measuring PRRSV replication and the viral load in PAMs. The different levels of susceptibility to PRRSV infection in PAMs may be associated with differences in the abundance of CD163 (PRRSV receptor), cytokines IL-8, IFN-γ, and TNF-α in Jiangquhai and Dingyuan pig breeds after viral inoculation.
PMID:
 
29691704
 
DOI:
 
10.1007/s00705-018-3821-y

Monday, April 16, 2018

Assessing PRRS area spread


 2018 Apr 14. doi: 10.1111/tbed.12875. [Epub ahead of print]

Assessment of area spread of porcine reproductive and respiratory syndrome (PRRS) virus in three clusters of swine farms.

Abstract

Despite decades of porcine reproductive and respiratory syndrome (PRRS) research, outbreaks with emerging and re-emerging PRRS virus (PRRSV) strains are not uncommon in North America. The role of area spread, commonly referred but not limited to airborne transmission, in originating such outbreaks is currently unknown. The main objective of this study was to explore the role of area spread on the occurrence of new PRRSV cases by combining information on genetic similarity among recovered PRRSV isolate's open-reading frame (ORF) 5 sequences and publicly available weather data. Three small regions were enrolled in the study for which high farm-level participation rate was achieved, and swine sites within those regions were readily sampled after reporting of an outbreak in a sow farm. Oral fluid PCR testing was used to determine PRRSV status of farms, and wind roses were generated for assessment of prevailing wind directions during 2-14 days preceding the outbreak. Under the conditions of this study, the data did not support the area spread theory as the main cause for these outbreaks. We suggest that for future studies, analysis of animal movement and other links between farms such as personnel, equipment and sharing of service providers should be incorporated for better insights on source of the virus. Furthermore, the development of rapid and easy diagnostic methods for ruling out resident PRRSV is urgently needed.

KEYWORDS: 

PRRS area spread; PRRS epidemiology; PRRS risk factors; porcine reproductive and respiratory syndrome; swine
PMID:
 
29654632
 
DOI:
 
10.1111/tbed.12875

Wednesday, April 4, 2018

Time series analysis for PRRS in the US

 2018 Apr 3;13(4):e0195282. doi: 10.1371/journal.pone.0195282. eCollection 2018.

Time-series analysis for porcine reproductive and respiratory syndrome in the United States.

Author information

1
Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, Ohio, United States of America.
2
Department of Veterinary Population Medicine, University of Minnesota, St. Paul, Minnesota, United States of America.
3
Department of Mathematics, Autonomous University of Barcelona, Barcelona, Spain.

Abstract

Industry-driven voluntary disease control programs for swine diseases emerged in North America in the early 2000's, and, since then, those programs have been used for monitoring diseases of economic importance to swine producers. One example of such initiatives is Dr. Morrison's Swine Health Monitoring Project, a nation-wide monitoring program for swine diseases including the porcine reproductive and respiratory syndrome (PRRS). PRRS has been extensively reported as a seasonal disease in the U.S., with predictable peaks that start in fall and are extended through the winter season. However, formal time series analysis stratified by geographic region has never been conducted for this important disease across the U.S. The main objective of this study was to use approximately seven years of PRRS incidence data in breeding swine herds to conduct time-series analysis in order to describe the temporal patterns of PRRS outbreaks at the farm level for five major swine-producing states across the U.S. including the states of Minnesota, Iowa, North Carolina, Nebraska and Illinois. Data was aggregated retrospectively at the week level for the number of herds containing animals actively shedding PRRS virus. Basic descriptive statistics were conducted followed by autoregressive integrated moving average (ARIMA) modelling, conducted separately for each of the above-mentioned states. Results showed that there was a difference in the nature of PRRS seasonality among states. Of note, when comparing states, the typical seasonal pattern previously described for PRRS could only be detected for farms located in the states of Minnesota, North Carolina and Nebraska. For the other two states, seasonal peaks every six months were detected within a year. In conclusion, we showed that epidemic patterns are not homogeneous across the U.S, with major peaks of disease occurring through the year. These findings highlight the importance of coordinating alternative control strategies in different regions considering the prevailing epidemiological patterns.
PMID:
 
29614099
 
DOI:
 
10.1371/journal.pone.0195282

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