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International meeting to combat devastating pig disease

Researchers gather to formulate virus control strategies

February 2011

Scientists and representatives from the pig industry met at The Roslin Institute, an Institute of BBSRC, on January 27-28 to discuss whether mathematical modelling can make a useful contribution against porcine reproductive and respiratory syndrome (PRRS), a disease that is estimated to cost the American swine industry around $600M a year (ref 1, ref 2).

Since its appearance in the late 1980s in North America, the mysterious condition, also known as Blue-Ear Pig Disease, has spread and devastated pig herds around the world. An outbreak in China in 2006 affected half the country and more than 2M pigs (ref 3). Similarly, in the US more than a fifth of all breeding herds and more than half of all farms with more than 500 sows were affected by PRRS (ref 4), meaning the disease is the major economic threat to commercial pig breeders as well as a significant animal welfare and global food security issue.

Respiratory failure in piglets is a common feature of PRRS. Image: iStockphoto

Respiratory failure in piglets is a common feature of PRRS.
Image: iStockphoto

"It is unlikely that PRRS can be overcome by a single approach alone," says BBSRC-funded researcher Dr Tahar Ait-Ali of the Roslin Institute who coordinated the meeting with his colleague Dr Andrea Doeschl-Wilson. "A multi-disciplinary approach is critical if one wants to defeat a devastating disease such as PRRS."

A causative virus, PRRSV, was identified in 1991 and since 1994 vaccines have been available but the virus is a formidable enemy (ref 5). It evolves rapidly and since it was first discovered American and European types have been categorised and there are now many genetic variants. This has caused challenges in vaccine production because inoculation against one viral strain does not protect against another, and previous BBSRC-funded projects conducted at The Roslin Institute have revealed several hundred porcine genes whose expression was altered following virus infection.

The disease results in respiratory failure in piglets, abortions in sows, and affected pigs exhibit clinical symptoms such as high fever and shivering, as well as characteristic blue ears caused by blood clotting in adults. It can also prove fatal because as it affects pigs' immune systems and leaves them vulnerable to other infections.

Dr Tahar Ait Ali (left) and Dr Andrea Wilson inspect piglets as part of their research. Image: Roslin Institute

Dr Tahar Ait Ali (left) and Dr Andrea Wilson inspect piglets as part of their research. Image: Roslin Institute

Tackling the disease is therefore an undertaking of major importance, and 35 experts from 10 countries gathered at Roslin to formulate a progress strategy. In particular, how mathematical models could usefully contribute to current PRRS research when matched to experimental studies, and how to combine results emerging from individual studies across the globe.

Professor Ait-Ali says Roslin has taken the lead with PRRS at international level. "Within the time frame of this workshop we have been able set the scene, identify critical knowledge-gaps and potential national and international collaborators for future high level multi-disciplinary collaborative projects to tackle PRRS."

The meeting forms part of the EuroPRRSnet initiative (ref 6), which aims to develop multidisciplinary collaborative research focused on epidemiology, immuno-pathology, vaccine development and diagnostics to understand the impact of the virus in Europe. EuroPRRSnet is funded by the European Cooperation in Science and Technology, and coordinated by The Roslin Institute at the University of Edinburgh.


  1. Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States (external link)
  2. National Pork Board
  3. Porcine respiratory and reproductive syndrome virus variants, Vietnam and China, 2007
  4. USDA Animal and Plant Health Inspection Service report (Part II: Reference of Swine Health & Health Management in the United States, 2000) (PDF, external link)
  5. EuroPRRSnet (external link)
  6. NCRA – Porcine reproductive and respiratory disease