Chronic Wasting Disease (CWD) is a transmissible
spongiform encephalopathy (TSE) affecting elk and deer (cervids)
in North America. This degenerative neurological illness has
affected both farmed and wild cervids in the US, thus impacting
the hunting and wildlife industries as well as domestic and international
markets for farmed cervids and cervid products. APHIS' response
to this disease includes support of surveillance in both farmed
and wild populations and assistance to State agencies for quarantine
of affected animals and premises, humane euthanasia, and testing
affected and exposed animals. In addition APHIS provides indemnity
to animal owners for the value of positive and exposed animals
euthanized in disease control efforts. A Herd Certification Program
(HCP) is being developed by APHIS in coordination with states,
the farmed cervid industry, and the US Animal Health Association
(USAHA) to support this effort. APHIS also has assisted, and
continues to assist, States with CWD surveillance and management
in wild cervid populations. Finally, APHIS is working with the
US Department of Interior, Tribes, and States to implement an
interagency, national plan to help manage CWD in captive and
wild cervids. For more detailed information on CWD and APHIS
response, read the fact sheets listed above. See also the VS
approach to free-ranging wildlife.
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CWD Diagnostics
The "gold
standard" diagnostic test for CWD is the Immunohistochemistry
(IHC) test performed on the obex tissue of the brain (right)
or specific lymphoid tissues. IHC testing is a method utilizing
antibody based staining which is evaluated using light microscopy.
This test is both sensitive and specific. In addition, the
microscopic methods used to detect positive staining also
allow confimation that the correct tissue and location within
the tissue are present to detect the earliest accumulations
of the prion agent. Other diagnostic tests utilizing enzyme-linked
immunosorbent assay (ELISA) and other technologies that allow
more rapid testing of larger numbers of samples have been,
and continue to be, developed. Several test kits using ELISA
and other technologies have recently been licensed by USDA's
Center for Veterinary Biologics for CWD diagnosis in wild
elk and deer. CWD testing can only be performed by approved
laboratories that are part
of the USDA Contract Laboratory system. A tonsillar biopsy
(live-animal) test has been developed by researchers in Colorado
and appears promising for certain CWD disease control or
management situations. This technique utilizes the current
IHC testing technologies described above.
Click here to read an APHIS
Position Paper on CWD Testing
Click here to view a map showing
the locations of the 26 USDA Contract laboratories for CWD,
or view the National
Veterinary Services Laboratories listing of laboratories
and contact points.
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Interagency
National Plan
The Management
Plan for Assisting States, Federal Agencies, and Tribes
in Managing Chronic Wasting Disease (CWD) in Wild and Captive
Cervids was developed by a task force including USDA,
the US Department of Interior, Tribal, and State representatives
at the request of Congress. This plan establishes a coordinated
approach to performing research and management actions
and for sharing information across geographic boundaries
and agency jurisdictions. It includes information on communications,
scientific and technical information dissemination, diagnostics,
disease management, research, and surveillance. To read
the Management Plan, click
here.
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