viruses can mutate, page-3

prrs vacine enourmous Australia's Deputy High Commissioner to Canada Tony Huber says, “The Australian government stands by its processes for import risk analysis.” He points out, “Pork is still entering Australia. The permits that had been issued with the exception of the single permit that Australian Pork Limited had the finding against are being exercised and will continue to be exercised.”

Huber states, “The Australian government intends to manage the ongoing issue through a combination of the legal challenge and an appeal to the original finding.” And adds, “It is also seeking to closely look at what the needs would be to ensure there is no such outcome as a closure of the border so there has never been a question on the part of the Australian government that there would be a closure of the border.”
Young Pigs Most Susceptible Just After Weaning
Post-weaning Multisystemic Wasting Syndrome is a relatively new condition first characterized in Western Canada in 1994-95. It only affects pigs and symptoms occur typically between about six weeks of age and 12 to 15 weeks of age at the point with when the pigs enter the nursery phase or the early grower phase. Clinical signs may include weight loss, difficulty breathing, enlargement of the lymph nodes or jaundice which signifies some degree of liver failure.
Clinical Disease Rare
Western College of Veterinary Medicine Associate Professor Dr. John Harding says there are two different outbreak scenarios.

“One is a low grade infection and that means that very few pigs would show clinical signs. It smolders but really doesn’t cause any substantial increase in mortality or level of sickness on those farms and obviously in that situation it is very controllable.”

He continues, “The flip side of that though is a situation where in some farms or in some countries we have a very explosive outbreak of severe disease which causes severe and high mortality. When farms become infected in that way, we call that the epidemic exposure, then they certainly have high mortality for a period of time, probably outwards of 16 to 24 months before it tends to subside and go back to pre-outbreak levels.”
Triggering Factors Unknown
The syndrome is caused by porcine circovirus type 2 but the factors that trigger an epidemic outbreak remain unclear. Dr. Harding says, “Some groups feel that there is another hidden virus that might be working collaboratively with circovirus. That hasn’t been proven. Other groups feel that there’s been a change in genetics or a change in management procedures but, to be honest, we really don’t have a good understanding of what the triggering factor is.”

Circovirus is nothing new. Dr. Harding says “Pigs have been infected with circovirus type two for the last 30 years. The development of severe clinical disease, which we call PMWS, has occurred gradually over the last ten years.”

“We reported some pigs or some farms in Canada back in 1994-95. France, in the Brittany area in ’97, had a very severe outbreak. Italy and Spain have had severe outbreaks. England has had a severe outbreak. Denmark is now struggling with an outbreak and we see more recently in the last several months the Quebec industry in Canada has now developed a severe outbreak situation as well. There is no question that there’s worldwide distribution of both the virus and the clinical disease.”
Good Management Best Defense
There is no one effective treatment for pigs that are affected by PMWS but Dr. Harding suggests, “What is very good for producers to concentrate on is just good management procedures so, with that, sanitation is important. Control of other diseases is very important. Proper pen density, proper air quality is important as well as timing of vaccinations to control other diseases.”

Dr. Harding points out, “Nobody would eradicate circovirus from farms so complete farm depopulation would not really be a preferred option. The reason for that is that circovirus, the virus that causes this is affecting all pigs in the countryside but only a very select few number of farms actually develop a severe clinical disease so really the control across any farm is instilling good management practices.”

Dr. Harding believes, “the important things to keep in mind are that circovirus is distributed worldwide.

Every country in every region in the world will have the virus.” He stresses, “There is no effect of circovirus on food safety. It can not cause disease in humans so, in spite of the fact we have the virus in the industry, it's not affecting human health in any way, whether from infecting humans or food safety.”
Australian Court Action Similar to U.S. Action Against Canadian Cattle
Dr. Wayne Lees, an epidemiologist with the Animal Disease Surveillance Unit of the Canadian Food Inspection Agency, suggests, “We have to make a clear distinction between the disease which is PMWS and the proposed agent which is porcine circovirus type 2.”

He compares what is happening in Australia with swine to that of the United States with cattle. “The situation in Australia is very similar actually to the situation that happened with BSE in the U.S. in that a judge has issued an injunction against the regulatory agency and has prohibited importation of product from abroad. Their own regulatory has really come to the conclusion that there is really not much risk for importing pigs from abroad in terms of introduction of the agent into the country.”

Dr. Less also points out, “The porcine circovirus type 2 has been found in most pig producing countries of the world, including Australia.”

“There’s a lot of research that’s being done in terms of linking the actual clinical disease syndrome with the virus,” he says, “Just because you have virus does not necessarily mean that you will become sick, if you are a pig. There are many other factors that seem to play into the expression of the disease over and above just the presence of the virus.”
Court Case Could Have Global Trade Implications
Canada Pork International continues to monitor the situation. Executive Director Jacques Pomerleau says what will happen once the existing Australian import permits expire remains unclear and he suggests the issue could have implications as far as Australia’s commitments to the World Trade Organization.

He points out, “Zero risk is not acceptable under the current trade conditions and obligations worldwide so the Australian government could find itself in a very difficult situation. They could be forced to rethink all of their import risk assessment.”
Australia Committed to World Trade Obligations
Huber insists, “As far as the Australian government approach to this has always been that we abide by our WTO commitments so, first and foremost, that's a stated principal.”

“Australia has a science based sanitary and phytosanitary system which we believe is in full conformity.” He insists, “The position of the government is quite clear. It stands by that system.”

Huber maintains, “The import risk analysis which leads to the issuance of import permits we believe is legal, has a strong science basis and would continue to be the basis for import permits being issued.” Adding, “This particular court case is something which we see needs to be resolved through the legal means however the policy would remain the same.”
Australia Hopes for Quick Resolution
Although there are no definite times frames, the Australian government has requested an expedited processing of the appeal. Huber is careful to separate the court case from the Australian government's policy approach.

“It is a legal issue,” he says, “We are approaching it that way and we are looking forward to a swift resolution in favor of the government policy as soon as possible.”