A major piece of research financed by Defra and the British Pig Executive (BPEX) has shed new light on the spread of PMWS.
The work was carried out by the University of Warwick and shows PMWS spread through Great Britain like an epidemic of a new infectious disease. The results will be presented to the Pig Veterinary Society at a meeting in Leeds on May 12 and 13.
A team of researchers collected data from 116 farms in England and Scotland from 2003 - 2004. Farmers were asked whether they had PMWS on their farm and when they first recognised the problem.
Analysis of the spread of PMWS indicate that the disease was present on a few farms in the south-east of England at the beginning of 2000. PMWS spread slowly north and west and entered Scotland in early 2003.
Factors that were associated with farms that broke down early in the epidemic were more than 600 sows and bringing in gilts.
During the FMD epidemic, when most animal movements stopped, farms that broke down were more likely to be located near a grower unit and allowed visitors onto their farm who were not three days pig free. After FMD, herd size and proximity to other pig farms were associated with introduction of PMWS.
The study was headed by Dr Laura Green who said: "The results from this first analysis indicate that introduction of PMWS may have occurred via pig movements, visitors and local spread . As with all infectious disease good biosecurity may help delay or prevent introduction to a farm. "
The main points to consider are:
• Careful purchasing and quarantine of new stock on farm reduce the risk of bringing new diseases onto a farm.
• Careful control of visitors to your farm (all visitors, not just vets) and insisting on 'three days pig free' is a practice that helps to protect the farm from new disease.
• Control of birds, rodents and other wildlife also assist in reducing disease.
Dr Green said: "These practices apply to all diseases. PMWS is a timely reminder of this."
The results of the study also indicated that reducing the impact of other diseases on the farm will reduce the impact of PMWS. This may include vaccination and new approaches to management to reduce cycling of disease on farm.
Dr Green also said the research team was very grateful for the co-operation of the farmers who took part in the study.
