Investigation of the epidemiology of PRRS
Investigation of the epidemiology of PRRS in England to provide a basis for surveillance and control programmes
The Royal Veterinary College (RVC) and the Veterinary Laboratories Agency (VLA)
Duration: 2009 – 2011
Porcine reproductive and respiratory syndrome (PRRS) is an economically devastating disease of swine throughout the world. Given the huge economic impact of PRRS, surveillance and control measures need to be targeted and cost-effective. Better understanding of the current situation and the epidemiology of PRRS in the UK is needed in order to design appropriate control programmes. A good surveillance system is necessary for early detection of introduction into a herd, successful control and eventual eradication.
Therefore the objective of this study was to provide a basis for the development of an adequate PRRS surveillance strategy.
Data and blood samples collected from 147 farms in 2008-2009 in the context of a cross-sectional study on PMWS were used to estimate the prevalence of PRRSV infection in England at herd level and then to identify the risk factors for active PRRSV infection at herd level. All samples were tested for antibodies against PRRS virus by ELISA test. On PRRS vaccinated farms, the presence of the virus in growers and finishers was determined using RT-PCR.
In 30.6% of all farms at least one growing or finishing pig tested positive for PRRS, indicating recent circulation of the virus on the farm. Regular vaccination for PRRS seemed to be common control measure with majority of farms using live virus vaccine.
The results of the risk factors analysis indicated that increased pig density, use of live virus vaccine, collection of dead pigs were associated with PRRS positive farms status. On the other hand, weaning of piglets at the age of 28 days or later was identified as protective factor for PRRS infection.
Current surveillance in place was evaluated using a quantitative method based on scenario tree modelling considering the epidemiology of PRRS including the risk factors identified. The results indicated that performance of the passive surveillance alone is not sufficient for successful control and or eradication of PRRS and that the enhancement of the surveillance for example, through the implementation of targeted surveillance would be recommended. Further, the results highlight the importance of farmers and veterinarians in detection of PRRS and thus in its control and eradication.
This project aimed to provide insight into the current PRRS situation which would provide a basis for development of a surveillance system tailored to the current PRRS situation in the UK assisting control and/or eradication of PRRS. With this project we aimed to contribute to improvement of the overall pig health, which will also have a positive impact on the competitiveness of British pork.
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