Spatial and temporal patterns of porcine reproductive and respiratory syndrome virus (PRRSV) genotypes in Ontario, Canada, 2004–2007

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Abstract

Background

The spread of PRRSV among pig herds has been investigated experimentally, but few observational studies have investigated this subject. Because PRRSV is endemic and live modified vaccines are used in Ontario, the spatial and temporal distributions of 6 PRRSV genotypes were investigated in the province during the period from 2004–2007. The purpose was to find evidence of spread of PRRSV genotypes and determine if spread could be attributed to supplier or ownership connections between herds. Sequence information from PRRSV ORF5 and related source-herd demographic information were obtained from diagnostic submissions to the Animal Health Laboratory, University of Guelph.

Results

A spatial cluster that could not be attributed to supplier or ownership connections among herds in the cluster was detected for RFLP type 1-3-4. Because of genetic dissimilarity among members of the cluster, it was considered to be a result of past spread of the RFLP type. A spatio-temporal cluster detected for RFLP type 1-18-4 was attributed to a shared gilt supplier among the herds in the cluster. Significant spatio-temporal patterns detected for RFLP type 2-5-2, which is considered to be a vaccine-type virus were most likely due to grouping of herds in an ownership that used the corresponding vaccine. Clustering within herd-ownership was a risk factor for presence of five of the six genotypes investigated in the present study.

Conclusions

Although the literature indicates that PRRSV can spread via aerosol between pig herds, the present study found no strong evidence of this occurring in Ontario. The evidence pointed toward transmission of PRRSV occurring in this population by common sources of animals or similarity of herd ownership, which is a proxy measure for other connections between herds. It is also apparent that the recognition and testing of these connections between herds is a necessary part of interpreting spatio-temporal patterns of PRRSV genotypes.

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Most cited references 28

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Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States.

Eric Neumann, James Kliebenstein, Colin Johnson … (2005)

To estimate the annual cost of infections attributable to porcine reproductive and respiratory syndrome (PRRS) virus to US swine producers. Economic analysis. Data on the health and productivity of PRRS-affected and PRRS-unaffected breeding herds and growing-pig populations were collected from a convenience sample of swine farms in the midwestern United States. Health and productivity variables of PRRS-affected and PRRS-unaffected swine farms were analyzed to estimate the impact of PRRS on specific farms. National estimates of PRRS incidence were then used to determine the annual economic impact of PRRS on US swine producers. PRRS affected breeding herds and growing-pig populations as measured by a decrease in reproductive health, an increase in deaths, and reductions in the rate and efficiency of growth. Total annual economic impact of these effects on US swine producers was estimated at dollar 66.75 million in breeding herds and dollar 493.57 million in growing-pig populations. PRRS imposes a substantial financial burden on US swine producers and causes approximately dollar 560.32 million in losses each year. By comparison, prior to eradication, annual losses attributable to classical swine fever (hog cholera) and pseudorabies were estimated at dollar 364.09 million and dollar 36.27 million, respectively (adjusted on the basis of year 2004 dollars). Current PRRS control strategies are not predictably successful; thus, PRRS-associated losses will continue into the future. Research to improve our understanding of ecologic and epidemiologic characteristics of the PRRS virus and technologic advances (vaccines and diagnostic tests) to prevent clinical effects are warranted.

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Phylogeny-based evolutionary, demographical, and geographical dissection of North American type 2 porcine reproductive and respiratory syndrome viruses.

Chung-Chau Hon, G. Davies, Li Li … (2010)

Type 2 (or North American-like) porcine reproductive and respiratory syndrome virus (PRRSV) was first recorded in 1987 in the United States and now occurs in most commercial swine industries throughout the world. In this study, we investigated the epidemiological and evolutionary behaviors of type 2 PRRSV. Based on phylogenetic analyses of 8,624 ORF5 sequences, we described a comprehensive picture of the diversity of type 2 PRRSVs and systematically classified all available sequences into lineages and sublineages, including a number of previously undescribed lineages. With the rapid growth of sequence deposition into the databases, it would be technically difficult for veterinary researchers to genotype their sequences by reanalyzing all sequences in the databases. To this end, a set of reference sequences was established based on our classification system, which represents the principal diversity of all available sequences and can readily be used for further genotyping studies. In addition, we further investigated the demographic histories of these lineages and sublineages by using Bayesian coalescence analyses, providing evolutionary insights into several important epidemiological events of type 2 PRRSV. Moreover, by using a phylogeographic approach, we were able to estimate the transmission frequencies between the pig-producing states in the United States and identified several states as the major sources of viral spread, i.e., "transmission centers." In summary, this study represents the most extensive phylogenetic analyses of type 2 PRRSV to date, providing a basis for future genotyping studies and dissecting the epidemiology of type 2 PRRSV from phylogenetic perspectives.

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Long-distance airborne transport of infectious PRRSV and Mycoplasma hyopneumoniae from a swine population infected with multiple viral variants.

Satoshi Otake, Scott Dee, Cesar Corzo … (2010)

Airborne transport of porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (M hyo) has been reported out to 4.7 km. This study attempted to determine whether this event could occur over longer distances and across multiple viral variants. To accomplish this goal, a mixed infection of 3 PRRSV variants (1-8-4, 1-18-2 and 1-26-2) and M hyo 232 was established in a source population of growing pigs. Over 21-day period, air samples were collected from the source population and at designated distances from the herd. Samples were tested for PRRSV RNA and M hyo DNA by PCR and if positive, further characterized. In exhaust air from the source population, PRRSV and M hyo were detected in 21 of 21 and 8 of 21 air samples, respectively. Five of 114 (4.4%) long-distance air samples were positive for PRRSV and 6 of 114 (5.2%) were positive for M hyo. The 5 PRRSV-positive samples were collected at 2.3, 4.6, 6.6 and 9.1 km from the herd. All contained infectious virus and were >99.2% homologous to PRRSV 1-8-4. No evidence of PRRSV 1-18-2 or 1-26-2 was detected in long-distance samples. All 6 M hyo-positive samples were 99.9% homologous to M hyo 232 and 3 samples (collected at 3.5, 6.8 and 9.2km from the herd) were infectious. These results indicate that airborne transport of PRRSV 1-8-4 and M hyo 232 occurs over longer distances than previously reported and that both pathogens remained infectious. Copyright © 2010 Elsevier B.V. All rights reserved.

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Author and article information

Contributors

Thomas Rosendal

Cate Dewey

Robert Friendship

Sarah Wootton

Beth Young

Zvonimir Poljak

Journal

Journal ID (nlm-ta): BMC Vet Res

Journal ID (iso-abbrev): BMC Vet. Res

Title: BMC Veterinary Research

Publisher: BioMed Central

ISSN (Electronic): 1746-6148

Publication date Collection: 2014

Publication date (Electronic): 5 April 2014

Volume: 10

Page: 83

Affiliations

[1 ]Department of Population Medicine, University of Guelph, Guelph, ON, Canada

[2 ]Department of Pathobiology, University of Guelph, Guelph, ON, Canada

Article

Publisher ID: 1746-6148-10-83

DOI: 10.1186/1746-6148-10-83

PMC ID: 4005473

PubMed ID: 24708804

SO-VID: f2bca397-b4ca-45db-ac22-d3b85b127163

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.

Spatial and temporal patterns of porcine reproductive and respiratory syndrome virus (PRRSV) genotypes in Ontario, Canada, 2004–2007

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Abstract

Background

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Horses and Humans Research Foundation

Most cited references 28

Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States.

Phylogeny-based evolutionary, demographical, and geographical dissection of North American type 2 porcine reproductive and respiratory syndrome viruses.

Long-distance airborne transport of infectious PRRSV and Mycoplasma hyopneumoniae from a swine population infected with multiple viral variants.

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