Dr McGraw is on the federal committee which has developed a vaccine for PED, which he called a devastating virus.

He said: "It will kill nearly 90 per cent of the baby pigs less than 10 days of age when it hits a farrowing farm.

"We estimate over seven million pigs have died from this virus in the last year. So the main concern is, let's not let it in and let's not let it spread."

The virus has hit some states so hard that there is great environmental concern about properly disposing of the carcasses of the affected pigs.

Although Wisconsin ranks 18th in the nation in pork production, Dr McGraw said PED has not hit the Badger State that hard.

He said: "We know of 14 lab accessions that have tested positive over the last year and a couple months. That doesn't mean that there's 14 farms - that could be a few farms that submitted more than one sample. But very low numbers compared to other states."

Wisconsin has 2,300 pork-producing operations which ship nearly one million pigs for processing every year. The virus is believed to have come from China and first showed up in the United States in May.

Dr McGraw has been proactive in increasing biosecurity in Wisconsin.

He added: "One concern is how this virus got in here, and I think it has elevated to the livestock industry as a whole the need for biosecurity. Let's look at what our current practices are and what can we do to prevent spread of disease. Let's not just talk about swine diseases but maybe cattle and sheep and goats."

Nationally, the PED virus has spread to more than 4,500 farms in 30 states.