Pennsylvania Game News - October 2013 - 27

(CJD) in humans. CWD affects only
members of the deer family.
How is it transmitted? CWD has a
very long incubation period compared
to most diseases, up to ﬁve years, but
averaging 12 to 24 months. It can be
transmitted both directly via contact
with saliva, urine or feces from infected
animals and indirectly by ingestion of
soil contaminated by prions from feces,
urine, saliva and decomposing carcasses
of infected animals, which can begin
shedding infectious prions as early as 11
months prior to showing any symptoms
of the disease. The prions that cause
CWD are virtually impossible to kill
and can remain infective in soil for
many years, probably forever.
How is it detected? CWD is detected through sampling and surveillance
of deer, both captive and free-ranging.
Pennsylvania is home to about 1,100
deer and elk farmers, with about 25,000
CWD-susceptible animals kept at
artificially high densities. There is
regular movement of animals between
farms and escapes are not uncommon.
The Pennsylvania Department of
Agriculture (PDA) has a CWD Herd
Certiﬁcation Program and Herd Monitoring Program for captive cervid farms,
including shooting preserves, which are
designed to manage the CWD status of
captive deer and elk herds.
Pennsylvania has been conducting active surveillance for CWD in
captive and hunter-killed deer since
1998, and has had a statewide interagency response plan in place since
2005. Initial response-plan activities
involved prevention, preparation and
early detection, and now that CWD
has been found in the state, disease
management activities have begun.
OCTOBER 2013

However, when the disease ﬁrst appears it is always at very low prevalence
(less than 1 percent), and in a patchy
distribution on the landscape making
detection difﬁcult.
How did we get CWD? We had
been preparing for the disease to arrive for more than a decade. We knew
it would come one of two ways: either
walking across the border, most likely
from the south where the disease is
established in West Virginia; or on a
truck, either as a live infected animal,
or as a carcass or taxidermy specimen
from a state or province that has CWD.
On Oct. 10, 2012, a 3½-year-old captive doe was conﬁrmed by the National
Veterinary Services Laboratory to have
died from CWD. This deer became ill
and died on a New Oxford (Adams
County) facility where, because she was
part of a captive deer herd registered
in PDA’s Cervid Herd Certiﬁcation
Program, her death from unknown
causes, but with signs consistent with
CWD, was investigated. During the
testing of remaining deer on this farm,
an apparently healthy adult male also
was determined to be CWD positive.
Results received this March from
the 2012 statewide testing of hunterkilled deer conﬁrmed CWD in three
free-ranging deer, two in Blair County
and one in Bedford County, some 54
miles away from the Adams County
cases. Their location is due north of
the established outbreak area in West
Virginia, which has been expanding to
the south and north since 2005. CWD
also was detected in a hunter harvested
deer in Maryland slightly more than 10
miles from the Pennsylvania state line
in 2011, directly in between these three
and the likely West Virginia source,
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Pennsylvania Game News - October 2013

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