According to Bent Nielsen, the head of SPF Health Control and the Pig Diagnostic Lab at the Danish Pig Research Centre, the spread of the disease in the US could have been made worse because of a lack of truck washing when pigs were taken to the slaughterhouse.

However, he said that although there have been cases in 2006 in Europe in Italy and Spain, the disease in Europe largely died out in the 1980s.

He said that it is believed that the current epidemic in the US could have come from China and was either brought in through personal contact, feed or from a migratory bird.

However, he added that the US has found that the transfer has not only been from pig to pig and from trucks but also that the disease has become airborne.

“Truck washing is highly critical and in some cases they were not washing the trucks when they went to the slaughterhouse,” Mr Nielsen said.

“That has caused the rapid spread in the US.”

Mr Nielsen added that although there is no vaccine against PED, in China a system of “feed-back” is used where a bit of infected gut is fed to pigs to immunise the piglets.

However, the precautions taken in the US are largely down to stamping out the disease.

He added that the disease has a short term effect, hitting the herd for about six weeks after which production can usually return.

“I hope we don’t get PED in Europe, but we know what to do if we do,” he said.

“It is short term because it only lasts for six weeks in one herd and then every farm will come back and produce normally again.”