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11 PERCENT SUB-CLINICAL CWD INFECTION RATE IN SAMPLE POP.

Preliminary Results for Research on Live Chronic Wasting Disease Test for
Elk in Rocky Mountain National Park

Date: April 10, 2008
Contact: Kyle Patterson, 970-586-1363

In January, research began in Rocky Mountain National Park to evaluate
procedures for testing live elk for chronic wasting disease (CWD). This is
the first time free ranging elk have been tested for CWD using this live
procedure. This study is being done at the park to take advantage of the
implementation of the recently announced Rocky Mountain National Park Elk
and Vegetation Management Plan.

Elk were captured from early January through mid March. The majority of
captures took place in Moraine Park and near Beaver Meadows Visitor Center.
Out of 136 female elk captured, (there were 117 usable biopsies), 13 tested
CWD positive and were removed. Complete necropsies were performed and
confirmed those results. Based on those results there was an 11 percent
estimated CWD prevalence rate in this sample population. At the time of
capture there was no obvious evidence of clinical CWD.

Researchers indicated they were not surprised at the results since previous
research in the park has shown that the elk herd in Rocky Mountain National
Park and the Estes Valley, is larger, less migratory and more concentrated
than it would be under natural conditions. Research has also shown that elk
densities on the core winter range are the highest concentrations ever
documented for a free-ranging population in the Rocky Mountains.

Over the next several years, in conjunction with the proposed lethal
reduction of elk, researchers will continue to conduct studies to evaluate
procedures for testing live elk for CWD. Currently, there is a live CWD test
effective for deer, but CWD diagnosis in live elk has received limited
evaluation to date. Until now, the disease could only be reliably diagnosed
after death in elk. Any elk which tests positive for CWD will be lethally
removed from the population, thereby contributing to annual population
reduction targets. These targets will be developed each year based on annual
population surveys and hunter success outside the park. Over the next three
years elk population reduction will gradually remove study elk and the CWD
status will be evaluated.

Chronic wasting disease (CWD) was first reported in free-ranging wildlife in
1981. It is a member of the transmissible spongiform encephalopathy (TSE)
disease family which also includes bovine spongiform encephalopathy in
cattle (BSE, also known as Mad Cow disease) and scrapie in domestic sheep
and goats. CWD is fatal in deer and elk. Northeastern Colorado (including
the eastside of Rocky Mountain National Park), southeastern Wyoming and
western Nebraska are considered the endemic area for the disease.

Participants in the studies include scientists from the Colorado State
University Department of Biomedical Sciences, the National Park Service,
USDA National Wildlife Research Center, Colorado State University Department
of Microbiology, Immunology and Pathology; USDA Agricultural Research
Service. The Colorado Division of Wildlife is participating in the study on
the live CWD test.

http://www.nps.gov/romo/parknews/pr_cwd_elk_research.htm

http://chronic-wasting-disease.blogspot.com/2008/04/11-percent-sub-clini...

CWD UPDATES

http://chronic-wasting-disease.blogspot.com/

April 2, 2008
New Scrapie Live-Animal
Test Approved
On Jan. 11, 2008, Veterinary Services (VS), a unit
within the U.S. Department of Agriculture's Animal
and Plant Health Inspection Service, approved a new
live-animal test for detecting scrapie in sheep and
goats. Similar to the currently used third eyelid test,
the test involves collecting lymphoid tissue. The new
test, however, uses rectal mucosa biopsy, as opposed
to third eyelid biopsy. Both tests can be conducted on
live animals using local anesthetic.

http://www.aphis.usda.gov/publications/animal_health/content/printable_v...

Brief Communications

Adaptation and evaluation of a rapid test for the diagnosis of sheep scrapie
in samples of rectal mucosa
Lorenzo González1, Robert Horton, Drew Ramsay, Reet Toomik, Valerie
Leathers, Quentin Tonelli, Mark P. Dagleish, Martin Jeffrey and Linda Terry
Correspondence: 1Corresponding Author: Lorenzo González, Veterinary
Laboratories Agency, Pentlands Science Park, Bush Loan, PENICUIK, Midlothian
EH26 0PZ, UK, e-mail: l.gonzalez@vla.defra.gsi.gov.uk

In recent publications, it was shown that disease-associated prion protein
(PrPd) accumulates in the lymphoid tissue of the rectal mucosa of a high
proportion of scrapie-infected sheep at clinical and preclinical stages,
regardless of several host factors; PrPd can also be detected in biopsy
specimens of rectal mucosa, with an increased probability proportional to
age or incubation period and with an efficiency almost identical to that of
tonsil biopsies. Rectal biopsies have the advantages of providing higher
numbers of lymphoid follicles and of being simpler to perform, which makes
them suitable for scrapie screening in the field. In biopsy samples, PrPd
could be demonstrated by immunohistochemical (IHC) and Western
immunoblotting methods, and the purpose of the present study was to optimize
and evaluate a "rapid test" for the diagnosis of scrapie in rectal biopsy
samples. The HerdChek CWD (chronic wasting disease) antigen EIA (enzyme
immunoassay) test was chosen and, once optimized, provided specificity and
sensitivity figures of 99.2% and 93.5%, respectively, compared with IHC
results in the same samples obtained at a postmortem. The sensitivity of the
assay increased from 82.1%, when a single rectal mucosa sample was tested to
99.4% for those sheep in which 3 or more samples were analyzed. Similarly,
sensitivity values of the HerdChek CWD antigen EIA test on biopsy samples
increased from 95% to 100% for sheep subjected to 1 or 2 sequential biopsies
4 months apart, respectively. Thus, a preclinical diagnosis of scrapie in
live sheep can be achieved by a combination of a simple sampling procedure,
which can be repeated several times with no detrimental effect for the
animals, and a rapid and efficient laboratory method.

Key Words: Rectal biopsy . scrapie . sheep

http://jvdi.org/cgi/content/abstract/20/2/203

AND

PrPCWD in rectal lymphoid tissue of deer (Odocoileus spp.)
Lisa L. Wolfe1, Terry R. Spraker2, Lorenzo González3, Mark P. Dagleish4,
Tracey M. Sirochman1,5, Jeremy C. Brown6, Martin Jeffrey3 and Michael W.
Miller1

1 Colorado Division of Wildlife, Wildlife Research Center, 317 West Prospect
Road, Fort Collins, CO 80526-2097, USA
2 Colorado State University Veterinary Diagnostic Laboratory, Colorado State
University, Fort Collins, CO 80523, USA
3 Veterinary Laboratories Agency - Lasswade, Pentlands Science Park,
Penicuik EH26 0PZ, UK
4 Moredun Research Institute, Pentlands Science Park, Penicuik EH26 0PZ, UK
5 Department of Molecular Biology, University of Wyoming, 1000 E. University
Avenue, Laramie, WY 82071, USA
6 Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range
Road, Laramie, WY 82070, USA

Correspondence
Lisa L. Wolfe
lisa.wolfe@state.co.us

The utility of rectal lymphoid tissue sampling for the diagnosis of chronic
wasting disease (CWD) infections in mule deer (Odocoileus hemionus) and
white-tailed deer (Odocoileus virginianus) was evaluated. CWD-associated
prion protein (PrPCWD) deposits were observed in the rectal mucosa from 19
orally inoculated mule deer by 381 days post-inoculation (p.i.); similarly,
45 out of 50 naturally infected mule deer had PrPCWD in their rectal mucosa.
In orally inoculated white-tailed deer, the presence of glycine (G) or
serine (S) at codon 96 of the native PrP (denoted 96GG, 96GS or 96SS)
appeared to influence the temporal patterns of PrPCWD deposition: nine out
of 11 infected 96GG individuals had PrPCWD in their rectal mucosa by 342
days p.i., whereas only three out of seven infected 96GS individuals had
PrPCWD in their rectal mucosa by 381 days p.i. and none of three 96SS
individuals had PrPCWD in their rectal mucosa by 751 days p.i. These
findings support further evaluation of rectal mucosa sampling in CWD
surveillance.

http://vir.sgmjournals.org/cgi/content/abstract/88/7/2078

REPORT OF THE COMMITTEE ON CAPTIVE
APHIS received approximately $18.5 million in appropriated CWD funding in FY
2006 ...

He then shared preliminary data on use of rectal mucosa biopsy to ...

http://www.usaha.org/committees/reports/2006/report-cwal-2006.pdf

2007

animals were tested in 2007 with the identification and removal of positive
elk from infected herds. Eighty percent of the positive animals in a highly
infected white-tailed deer herd were identified with *** rectal biopsy. The
lower incidence of CWD in most infected elk herds complicates the evaluation
of this test in elk. It appears that in deer, rectal lymphoid tissue becomes
positive later than lymphoid tissue of the head suggesting that early cases
may be missed with rectal biopsy. Positive rectal biopsy is indicative of
disease but a negative rectal biopsy test does not rule out CWD in an
individual or herd.

http://www.usaha.org/committees/reports/2007/report-cwal-2007.pdf

SOMETHING OF INTEREST

Title: Detection of PrP**CWD in retinal tissues in white-tailed deer
(Odocoileus virginianus) and Rocky Mountain elk (Cervus elaphus nelsoni)
with CWD

http://www.ars.usda.gov/research/publications/publications.htm?seq_no_11...

A prion disease of cervids: Chronic wasting disease 2008

http://chronic-wasting-disease.blogspot.com/2008/04/prion-disease-of-cer...

TSS Brick Wall,)

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Joined: 01/01/2006
Posts: 230
11 PERCENT SUB-CLINICAL CWD INFECTION RATE IN SAMPLE POP.

Wildlife Disease Research Program

TITLE: Evaluation and Management of Chronic

Wasting Disease (CWD) Transmission

GOAL: To assess the potential for CWD

transmission at the interface between

wild and domestic cervids and to develop

methods to reduce transmission and

spread.

snip...see bottom of page 3 ;

Development of a Live-Animal Test for Detecting

CWD in Elk—Until recently, there was no practical

live-animal test for detecting CWD in elk. Collaborations

among CSU, APHIS VS, the Agricultural

Research Service, the Canadian Food Inspection

Agency, several private elk ranchers, and NWRC

scientists have yielded a rectal biopsy method for

detecting CWD in infected elk that have not yet displayed

CWD symptoms. The test is beginning to be

used operationally by VS and private elk ranchers.

http://www.aphis.usda.gov/wildlife_damage/nwrc/publications/accomplishme...

Detection of PrPCWD in postmortem rectal lymphoid tissues in Rocky

Mountain elk (Cervus elaphus nelsoni) infected with chronic

wasting disease

Terry R. Spraker,1 Thomas L. Gidlewski, Aru Balachandran, Kurt C. VerCauteren,

Lynn Creekmore, Randy D. Munger

Abstract. Preclinical diagnostic tests for transmissible spongiform encephalopathies have been described

for mule deer (Odocoileus hemionus), using biopsy tissues of palatine tonsil, and for sheep, using lymphoid

tissues from palatine tonsil, third eyelid, and rectal mucosa. The utility of examining the rectal mucosal

lymphoid tissues to detect chronic wasting disease (CWD) was investigated in Rocky Mountain elk (Cervus

elaphus nelsoni), a species for which there is not a live-animal diagnostic test. Postmortem rectal mucosal

sections were examined from 308 elk from two privately owned herds that were depopulated. The results of the

postmortem rectal mucosal sections were compared to immunohistochemical staining of the brainstem,

retropharyngeal lymph nodes, and palatine tonsil. Seven elk were found positive using the brainstem (dorsal

motor nucleus of the vagus nerve), retropharyngeal lymph nodes, and palatine tonsil. Six of these elk were also

found positive using postmortem rectal mucosal sections. The remaining 301 elk in which CWD-associated

abnormal isoform of the prion protein (PrPCWD) was not detected in the brainstem and cranial lymphoid

tissues were also found to be free of PrPCWD when postmortem rectal mucosal sections were examined. The use

of rectal mucosal lymphoid tissues may be suitable for a live-animal diagnostic test as part of an integrated

management strategy to limit CWD in elk.

see full text ;

http://www.aphis.usda.gov/wildlife_damage/nwrc/publications/06pubs/verca...

Project Accomplishments 2007

Validation of a Live Test for CWD—In 2006, a practical live test for CWD in elk was developed by NWRC scientists in cooperation with CSU and APHIS’ Veterinary Services. Scientists are continuing to refine the methods and are now fully developing, evaluating, and validating a rectal biopsy method so it can be used as a tool for detecting CWD in cervids that have been infected but have not yet begun to show signs of disease. The technique is currently being used in pen studies to determine time to infection relative to transmission route.

http://www.aphis.usda.gov/wildlife_damage/nwrc/research/cwd/accomplishme...

tss

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