| Will Verboven, Contributing Editor
CWD Bigger Threat Than BSE
Dr. Jean -Philippe Deslys is a research scientist, author and expert advisor to the French government and a host of international health agencies, including the World Health Organization and the U.S. Food and Drug Agency. Dr. Deslys has been named as the current Project Coordinator for the European Union Neuroprion Network of Excellence, and has made many presentations across North America, including to the Canadian Food Inspection Agency and the Canadian Institutes of Health Research. His research, as leader of a scientific team at the CEA (French Atomic Energy Commission), was instrumental in the development of the BSE rapid test, which is in widespread use across Canada today
In this recent interview, he comments on BSE testing procedures and standards in Canada and the USA. He also comments on Chronic Wasting Disease, a BSE-related disease of elk and deer and how it should be of more concern to the North American public – particularly because it is uncontrollable.
Dr. Deslys’s most recent research, published this spring in the British-based medical journal The Lancet, provides preliminary estimates regarding the risk of contracting variant Creutzfeldt-Jakob disease, the “human form” of BSE or vCJD, via oral means (i.e. by eating BSE-infected material).
WV
What is your view on the circumstances surrounding the recent BSE case that was diagnosed in the USA?
Dr. Deslys
Technically this case was discovered last November through a rapid BSE screening test, but then at the confirmatory level there was a problem with the immunohostochemistry (IHC) test, which did not give the same results. Unlike North America, in Europe a first confirmation is usually done by the more reliable western blot test and then the follow up can be performed with the IHC test – which is more complicated. I say “complicated” because IHC is still a non-standardized technique and its efficiency depends on both the protocol being used and even on the technicians involved.
WV
Will the ELISA and western blot BSE tests become sensitive enough hopefully to avoid what happened in the USA?
Dr. Deslys
These are now the main tests that are being used because they are simpler and more reliable. We only use IHC when there is a problem with those two tests, because an IHC provides more information.
WV
Mandatory BSE testing of cattle over 30 months is being resisted in Canada and the USA. Have you seen any changes in that official attitude in North America?
Dr. Deslys
What I understand from North America is that to apply the same testing levels that are used in Europe is technically difficult, because the traceability of cattle being tested is not perfect for all animals. In other words, it is difficult to guarantee the age of the animals to be tested. Another measure to take to avoid this problem is to do what the Japanese have done and test everything, which gives you time to set up systems for accurate traceability. But then we come to economic considerations around testing – do we test everything to reassure consumers and export markets and avoid borders being shut? Or do we wait and see, maybe until the problem disappears?
WV
What is the situation with a goat developing BSE in France? Are there concerns with this?
Dr. Deslys
All goats in France are tested for BSE to identify any other cases; to date all subsequent test results have proven negative. There is still a concern because there is no real barrier between small ruminants and cattle, meaning that BSE can be transmitted to small ruminants through infected feed. But I expect only sporadic cases, if any, to appear, taking into account the fact that the only BSE-positive goat identified so far is an old case, in an animal slaughtered in 2002, born before the total ban on meat and bone meal.
WV
What about the potential of finding BSE cases in South America, Africa or Australia?
Dr. Deslys
There is always a connection between the number of times BSE tests are done and the number of cases discovered. Of course for countries that do little or no testing there should be no surprise that they do not find any BSE cases. It seems that the U.S. and Canada will not continue to increase the number of tests they do, which is consistent so as long as tests are not being done to protect health, but for surveillance purposes only. Once you believe your course of surveillance to be complete, then the natural tendency is to stop testing as soon as possible.
WV
There has been an announcement by a company in Calgary that they have developed a live test for BSE. What is your view on that potential?
Dr. Deslys
At the moment I have not seen any validation of these tests. In Europe, we regularly observe such claims from companies engaged in this kind of research, seeking financial support, but until now, none of their claims have been confirmed.
WV
How do you see BSE and TSE research developing over the next few years in Europe?
Dr. Deslys
To avoid the possibility of any new prion-linked crises, European research has been integrated under NeuroPrion, a network which coordinates most organizations doing prion disease research across the EU. Part of our work includes organizing the main worldwide congresses in the prion field each year to ascertain how research is developing. This year, Prion will be held in Düsseldorf, Germany on October 19-21. Our goal is to ensure that Europe will maintain leadership in the field of prion research due to the tremendous investment that has been made. Because of the economic impact of BSE, it is clearly in Europe’s best interest to lead the way with public research. In terms of trends, I expect new insight into diagnosis of TSE’s in blood in both humans and animals.
WV
Do you see Chronic Wasting Disease (CWD) in elk and deer, which is unique to North America, as requiring more research?
Dr. Deslys
Clearly yes it requires more research because of its spread from two small clusters in the 1960s in Colorado and Wyoming, first to more central U.S. states and then into Canada and now even to New York State. CWD is even more dangerous than the TSE scrapie in sheep because you can have 100 percent lateral transmission between animals, and even environmental contamination, which can affect new animals to an infected territory.
WV
Is there any way to control spread of CWD?
Dr. Deslys
Research needs to be developed especially to assess any risk to humans. When CWD was limited to small clusters, very few people would have been in contact with the disease. There was a vast difference in the situation with BSE in the UK where there were many cases and a large number of people exposed to the risk. Here we saw that the disease evolved with very serious human consequences. A similar situation with CWD needs to be avoided, and large scale testing can be very efficient in disease identification and control in this regard. But at the moment, we see no indication that a similar virulence to humans exists with CWD. The research challenge will be to prove that CWD is not dangerous for humans.
WV
Is the CWD prion different from other prions, causing it to act so differently?
Dr. Deslys
With these diseases we have two factors at work; one linked to the host and one linked to the disease agent. Depending on each factor, the distribution of infectivity is affected. CWD seems to be linked at the level of the host to a higher level of infectivity in tissue than other prion diseases.
WV
What do see as the bigger threat to North America: BSE or CWD?
Dr. Deslys
BSE, with proper measures, is probably not going to increase in North America. The worse disease is CWD because it is spreading and difficult to control, mainly because it can be spread through the movement of wild animal populations. But we must understand that BSE is more dangerous to the economy, so the scenarios for effectively dealing with the two are quite different.
WV
Where do you see BSE in North America and Europe in ten years?
Dr. Deslys
I think in Europe we will continue to use BSE testing until we are assured that the disease has disappeared. Even if cases continue to arise in the UK or Eastern Europe, people will not care because measures such as systematic testing and removal of SRMs are in place to protect human health. For the rest of the world, an increase in BSE surveillance would offer greater security.
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