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I am a senior at Michigan State University studing Agriscience and for one of my classes I have chosen to do a report on CWD pertaining to the US and Canada. The class has to do with biosecurity and how things can and are being introduced to the US either accidentally or as possible terrorism. For example we have talked about how the emerald ash borer has been accidently introduced into southern Michigan. As hunters I would like to know what you have ideas about CWD. What do you think of the regulations for cervids entering from Canada? Have any of you had any experience crossing the border from a Canadian hunt lately? Was it a good or bad experiance? What are your thought on CWD in Michigan? Do you think it will eventually end up here? How will it effect Michigan Hunting? What do you think about the type of info that is out there for hunters to educate them about CWD? Is there enough info or should we be more informed? I know what my answers for these questions are but I would like a broader hunting population to show their thoughts. Any help you can give me will be greatly helped it will give me more ideas to look at when I present the topic. Also any websites that you think will help me with finding CWD info will be greatly appreciated.

Thanks for any help you can give
Sarah
 

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hello Sarah,

there are many other dangerous pathogens that would be
more suited for biological warfare due to the
long incubation period of TSEs. most terrorist
would want to see something happen that
would do damage to human/animal/economy
in a more faster mode other than TSEs, such
as Anthrax, FMD, Ebola Haemorrahagic Fever,
Salmonella, E.Coli O157:H7, etc etc. not to say some nut
could/would not use TSEs. i made a submission about this
very thing with TSEs and the _potential_ for this exact scenerio
with Air Passenger Travel and TSEs;

# Docket No: 02-088-1 RE-Agricultural Bioterrorism Protection Act of
2002; [TSS SUBMISSION ON POTENTIAL FOR BSE/TSE & FMD 'SUITCASE BOMBS'] -
TSS 1/27/03 (0)

http://www.vegsource.com/talk/madcow/messages/9912395.html

also, if you want some data on CWD and other TSEs including
TSEs in cattle in the USA, you can search here if you like;


http://disc.server.com/Indices/167318.html


http://www.vegsource.com/talk/madcow/index.html


if you would like, i can send you more data to your private
email, just email me [email protected] OR go to
google search and type in ''terry s. singeltary sr.'' or ''mad cow tss''
and you may find a few hits.

please remember, CWD is a small portion of a much larger problem
here in the USA i.e. TSE in USA cattle...

Gerald Wells: Report of the Visit to USA, April-May 1989

snip...

The general opinion of those present was that BSE, as an
overt disease phenomenon, _could exist in the USA, but if it did,
it was very rare. The need for improved and specific surveillance
methods to detect it as recognised...

snip...

It is clear that USDA have little information and _no_ regulatory
responsibility for rendering plants in the US...

snip...

3. Prof. A. Robertson gave a brief account of BSE. The US approach
was to accord it a _very low profile indeed_. Dr. A Thiermann showed
the picture in the ''Independent'' with cattle being incinerated and thought
this was a fanatical incident to be _avoided_ in the US _at all costs_...

snip...

http://www.bseinquiry.gov.uk/files/mb/m11b/tab01.pdf

To be published in the Proceedings of the
Fourth International Scientific Congress in
Fur Animal Production. Toronto, Canada,
August 21-28, 1988

Evidence That Transmissible Mink Encephalopathy
Results from Feeding Infected Cattle

R.F. Marsh* and G.R. Hartsough

•Department of Veterinary Science, University of Wisconsin-Madison, Madison,
Wisconsin 53706; and ^Emba/Creat Lakes Ranch Service, Thiensville, Wisconsin 53092

ABSTRACT
Epidemiologic investigation of a new incidence of
transmissible mink encephalopathy (TME) in Stetsonville, Wisconsin
suggests that the disease may have resulted from feeding infected
cattle to mink. This observation is supported by the transmission of
a TME-like disease to experimentally inoculated cattle, and by the
recent report of a new bovine spongiform encephalopathy in
England.

INTRODUCTION

Transmissible mink encephalopathy (TME) was first reported in 1965 by Hartsough
and Burger who demonstrated that the disease was transmissible with a long incubation
period, and that affected mink had a spongiform encephalopathy similar to that found in
scrapie-affecied sheep (Hartsough and Burger, 1965; Burger and Hartsough, 1965).
Because of the similarity between TME and scrapie, and the subsequent finding that the
two transmissible agents were indistinguishable (Marsh and Hanson, 1969), it was
concluded that TME most likely resulted from feeding mink scrapie-infecied sheep.
The experimental transmission of sheep scrapie to mink (Hanson et al., 1971)
confirmed the close association of TME and scrapie, but at the same time provided
evidence that they may be different. Epidemiologic studies on previous incidences of
TME indicated that the incubation periods in field cases were between six months and
one year in length (Harxsough and Burger, 1965). Experimentally, scrapie could not be
transmitted to mink in less than one year.
To investigate the possibility that TME may be caused by a (particular strain of
scrapie which might be highly pathogenic for mink, 21 different strains of the scrapie
agent, including their sheep or goat sources, were inoculated into a total of 61 mink.
Only one mink developed a progressive neurologic disease after an incubation period of
22 mon..s (Marsh and Hanson, 1979). These results indicated that TME was either caused
by a strain of sheep scrapie not yet tested, or was due to exposure to a scrapie-like agent
from an unidentified source.

OBSERVATIONS AND RESULTS

A New Incidence of TME. In April of 1985, a mink rancher in Stetsonville, Wisconsin
reported that many of his mink were "acting funny", and some had died. At this time, we
visited the farm and found that approximately 10% of all adult mink were showing
typical signs of TME: insidious onset characterized by subtle behavioral changes, loss of
normal habits of cleanliness, deposition of droppings throughout the pen rather than in a
single area, hyperexcitability, difficulty in chewing and swallowing, and tails arched over
their _backs like squirrels. These signs were followed by progressive deterioration of
neurologic function beginning with locomoior incoordination, long periods of somnolence
in which the affected mink would stand motionless with its head in the corner of the
cage, complete debilitation, and death. Over the next 8-10 weeks, approximately 40% of
all the adult mink on the farm died from TME.
Since previous incidences of TME were associated with common or shared feeding
practices, we obtained a careful history of feed ingredients used over the past 12-18
months. The rancher was a "dead stock" feeder using mostly (>95%) downer or dead dairy
cattle and a few horses. Sheep had never been fed.

Experimental Transmission. The clinical diagnosis of TME was confirmed by
histopaihologic examination and by experimental transmission to mink after incubation
periods of four months. To investigate the possible involvement of cattle in this disease
cycle, two six-week old castrated Holstein bull calves were inoculated intracerebrally
with a brain suspension from affected mink. Each developed a fatal spongiform
encephalopathy after incubation periods of 18 and 19 months.

DISCUSSION
These findings suggest that TME may result from feeding mink infected cattle and
we have alerted bovine practitioners that there may exist an as yet unrecognized
scrapie-like disease of cattle in the United States (Marsh and Hartsough, 1986). A new
bovine spongiform encephalopathy has recently been reported in England (Wells et al.,
1987), and investigators are presently studying its transmissibility and possible
relationship to scrapie. Because this new bovine disease in England is characterized by
behavioral changes, hyperexcitability, and agressiveness, it is very likely it would be
confused with rabies in the United Stales and not be diagnosed. Presently, brains from
cattle in the United States which are suspected of rabies infection are only tested with
anti-rabies virus antibody and are not examined histopathologically for lesions of
spongiform encephalopathy.
We are presently pursuing additional studies to further examine the possible
involvement of cattle in the epidemiology of TME. One of these is the backpassage of
our experimental bovine encephalopathy to mink. Because (here are as yet no agent-
specific proteins or nucleic acids identified for these transmissible neuropathogens, one
means of distinguishing them is by animal passage and selection of the biotype which
grows best in a particular host. This procedure has been used to separate hamster-
adapted and mink-udapted TME agents (Marsh and Hanson, 1979). The intracerebral
backpassage of the experimental bovine agent resulted in incubations of only four months
indicating no de-adaptation of the Stetsonville agent for mink after bovine passage.
Mink fed infected bovine brain remain normal after six months. It will be essential to
demonstrate oral transmission fiom bovine to mink it this proposed epidemiologic
association is to be confirmed.

ACKNOWLEDGEMENTS
These studies were supported by the College of Agricultural and Life Sciences,
University of Wisconsin-Madison and by a grant (85-CRCR-1-1812) from the United
States Department of Agriculture. The authors also wish to acknowledge the help and
encouragement of Robert Hanson who died during the course of these investigations.

REFERENCES
Burger, D. and Hartsough, G.R. 1965. Encephalopathy of mink. II. Experimental and
natural transmission. J. Infec. Dis. 115:393-399.
Hanson, R.P., Eckroade, R.3., Marsh, R.F., ZuRhein, C.M., Kanitz, C.L. and Gustatson,
D.P. 1971. Susceptibility of mink to sheep scrapie. Science 172:859-861.
Hansough, G.R. and Burger, D. 1965. Encephalopathy of mink. I. Epizoociologic and
clinical observations. 3. Infec. Dis. 115:387-392.
Marsh, R.F. and Hanson, R.P. 1969. Physical and chemical properties of the
transmissible mink encephalopathy agent. 3. ViroL 3:176-180.
Marsh, R.F. and Hanson, R.P. 1979. On the origin of transmissible mink
encephalopathy. In Hadlow, W.J. and Prusiner, S.P. (eds.) Slow transmissible
diseases of the nervous system. Vol. 1, Academic Press, New York, pp 451-460.
Marsh, R.F. and Hartsough, G.R. 1986. Is there a scrapie-like disease in cattle?
Proceedings of the Seventh Annual Western Conference for Food Animal Veterinary
Medicine. University of Arizona, pp 20.
Wells, G.A.H., Scott, A.C., Johnson, C.T., Cunning, R.F., Hancock, R.D., Jeffrey, M.,
Dawson, M. and Bradley, R. 1987. A novel progressive spongiform encephalopathy
in cattle. Vet. Rec. 121:419-420.

MARSH

http://www.bseinquiry.gov.uk/files/mb/m09/tab05.pdf


good luck with your thesis...

TSS
 
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