Creutzfeldt-Jakob disease (CJD) is a fatal neurologic disorder in humans.
CJD is one of a group of conditions known as transmissible spongiform encephalopathies
(TSEs), or prion diseases, that are believed to be caused by abnormally configured,
host-encoded prion proteins that accumulate in the central nervous tissue.1 CJD has an annual incidence of approximately 1
case per million population in the United States1 and
occurs in three forms: sporadic, genetically determined, and acquired by infection.
In the latter form, the incubation period is measured typically in years.
Recent evidence that prion infection can cross the species barrier between
humans and cattle has raised increasing public health concerns about the possible
transmission to humans of a TSE among deer and elk known as chronic wasting
disease (CWD).2 During 1993-1999, three
men who participated in wild game feasts in northern Wisconsin died of degenerative
neurologic illnesses. This report documents the investigation of these deaths,
which was initiated in August 2002 and which confirmed the death of only one
person from CJD. Although no association between CWD and CJD was found, continued
surveillance of both diseases remains important to assess the possible risk
for CWD transmission to humans.
Case 1. In December 1992, a Wisconsin man aged 66 years with a history of seizures
since 1969 sought treatment for recurring seizures, increasing forgetfulness,
and worsening hand tremors. Electroencephalographic (EEG) examination demonstrated
focal epileptiform activity and nonspecific diffuse abnormalities, but no
specific diagnosis was made. In February 1993, he was hospitalized for increasing
confusion, ataxia, and movement tremors of his extremities. A magnetic resonance
image (MRI) demonstrated mild, nonspecific enhancement along the inferior
parasagittal occipital lobe. A repeat EEG showed bifrontal intermittent, short-interval,
periodic sharp waves, suggesting a progressive encephalopathy; a diagnosis
of CJD was suspected. The man died later that month; neuropathologic examination
of brain tissue during autopsy indicated subacute spongiform encephalopathy,
compatible with CJD.
The man was a lifelong hunter who ate venison frequently. He hunted
primarily in northern Wisconsin but also at least once in Montana. He hosted
wild game feasts at his cabin in northern Wisconsin from 1976 until shortly
before his death. Fixed brain tissue obtained during the autopsy was sent
for analysis to the National Prion Disease Pathology Surveillance Center (NPDPSC)
and reexamined at the institution where the autopsy was conducted. Histopathologic
examination did not substantiate the diagnosis of prion disease. In addition,
27 brain tissue sections were negative for prions by immunostaining despite
positive antibody reactions against other proteins (controls), which indicated
that other epitopes in the tissue samples were preserved.
Case 2. In May 1999, a Minnesota man aged 55 years with no previous history
of a neurologic disease sought evaluation and treatment following a 3-month
history of progressive difficulty in writing and unsteadiness of gait. A computerized
tomography (CT) scan and MRI examination of his head did not indicate any
abnormality. In June 1999, he was hospitalized following onset of dementia,
speech abnormalities, and myoclonic jerking. An EEG indicated left-hemispheric
periodic sharp waves and moderate generalized background slowing; CJD was
diagnosed clinically. In July 1999, following worsening symptoms and development
of right upper extremity dystonia, the patient died. Neuropathologic evaluation
of brain tissue during autopsy demonstrated widespread subcortical spongiform
lesions, consistent with CJD.
The man was not a hunter but had a history of eating venison. He made
an estimated 12 visits to the cabin where the wild game feasts were held,
but he participated in only one feast during the mid-1980s. Sections of fixed
and frozen brain tissue obtained during autopsy were analyzed at NPDPSC, and
prion disease was confirmed by immunohistochemical and Western blot testing.
The Western blot characteristics and prion disease phenotype in this patient
were consistent with the most common form of sporadic CJD, classified as M/M
(M/V) 1.3 Subsequent genetic typing confirmed
the presence of methionine homozygosity (M/M) at codon 129 of the patient's
prion protein gene.
Case 3. In June 1992, a Wisconsin man aged 65 years sought treatment for progressive
slowing of speech, worsening memory, and personality changes. By January 1993,
his speech was reduced to one-word utterances. Neurologic examination showed
a flat affect, decreased reflexes, and apraxia. A CT head scan showed mild
atrophy, and an EEG was normal. Pick's disease was diagnosed. By May, he was
unable to perform any daily living activities; he died in August 1993. Neuropathologic
evaluation of brain tissue during autopsy showed symmetrical frontal lobe
cerebral cortical atrophy and mild temporal lobe atrophy. No Pick's bodies
or spongiform lesions were observed.
The man had a history of eating venison and participated regularly in
wild game feasts held at the cabin owned by patient 1. He was a lifelong hunter
and hunted mostly in Wisconsin but also in Wyoming and British Columbia. No
game was brought to the wild game feasts from his hunting trips outside of
Wisconsin. Examination of fixed brain tissue sent to NPDPSC demonstrated no
lesions indicative of CJD, and immunohistochemical testing with antibody to
the prion protein did not demonstrate the granular deposits seen in prion
Wild game feasts consisting of elk, deer, antelope, and other game that
occurred at a cabin in northern Wisconsin owned by patient 1 began in 1976
and continued through 2002. These feasts typically involved 10-15 participants
and usually occurred on weekends before or during hunting seasons in the fall
and occasionally in the spring. Wild game brought to these feasts usually
were harvested in Wisconsin, but three men who attended these feasts reported
hunting in the western United States and bringing game back to Wisconsin.
These activities took place in Colorado (near the towns of Cortez, Trinidad,
Collbran, Durango, and Meeker), Wyoming (near the towns of Gilette and Cody),
and Montana (near the town of Malta). CWD was not known to be endemic in these
areas at the time that these hunting activities took place.
Information was obtained for 45 (85%) of 53 persons who were identified
as possibly participating in the wild game feasts; all were male. Information
was obtained by direct interview or from family members of decedents. Of the
45 persons, for whom information was obtained, 34 were reported to have attended
wild game feasts. Seven of the 34 feast attendees were deceased, including
the three patients. None of the four other decedents had a cause of death
attributed to or associated with a degenerative neurologic disorder. None
of the living participants had any signs or symptoms consistent with a degenerative
JP Davis, MD, J Kazmierczak, DVM, M Wegner, MD, R Wierzba, Div of Public
Health, State of Wisconsin Dept of Health and Family Svcs. P Gambetti, National
Prion Disease Pathology Surveillance Center, Case Western Reserve University,
Cleveland, Ohio. L Schonberger, MD, R Maddox, MPH, E Belay, MD, Div of Viral
and Rickettsial Diseases, National Center for Infectious Diseases; V Hsu,
MD, EIS Officer, CDC.
CWD was first described in the United States in the 1960s and classified
as a TSE in 1978. Previously localized to a contiguous endemic area in northeastern
Colorado and southeast Wyoming, since 2000, CWD has been found in free-ranging
deer or elk in Illinois, Nebraska, New Mexico, South Dakota, Wisconsin, and
outside the previously known endemic areas of Colorado and Wyoming. CWD has
been identified also in captive deer or elk in Colorado, Kansas, Minnesota,
Montana, Nebraska, Oklahoma, South Dakota, and Wisconsin.4 Because
a variant form of CJD, with specific neuropathologic and molecular characteristics
that distinguish it from sporadic CJD, has been associated with eating cattle
products infected with a prion that causes bovine spongiform encephalopathy,5 concern has been raised about the possibility that
the prion associated with CWD might be transmitted to humans in a similar
In this investigation, because only one of the three cases in Wisconsin
had neuropathologic confirmation of a prion disease, no association could
be made between case participation in the wild game feasts and the development
of CJD. Although patient 2 had confirmed CJD, he was unlikely to have eaten
CWD-infected venison at these feasts because venison and other game from outside
Wisconsin that was served at these feasts did not originate from known CWD-endemic
areas, and the man participated in the feasts only once. In addition, the
prion disease in this case was consistent with the most common form of sporadic
CJD, without apparent unusual neuropathologic or molecular characteristics
that might occur if the prion related to CWD had been responsible for the
The findings in this report are subject to at least two limitations.
First, not all members participating in wild game feasts could be identified,
and not all persons listed as participating could be contacted for interviews.
Second, interviews that were conducted required recall of events that occurred
up to 25 years ago, limiting the detail or accuracy of events. However, the
similar responses obtained from different sources support the accuracy of
the investigation findings.
A previous investigation of unusually young CJD patients in whom the
transmission of CWD was suspected also did not provide convincing evidence
for a causal relationship between CWD and CJD.2 However,
limited epidemiologic investigations cannot rule out the possibility that
CWD might play a role in causing human illness. Ongoing surveillance of CJD,
particularly in states with CWD, is important to assess the risk, if any,
for CWD transmission to humans. Because the confirmation of CJD and the detection
of a new prion disease require neuropathologic study of brain tissue, physicians
are encouraged to contact NPDPSC (http://www.cjdsurveillance.com;
telephone, 216-368-0587) to confirm diagnoses of CJD and to distinguish its
various subtypes. Because of the known severity of TSEs in humans and the
possibility that the CWD prion can affect humans, animals with evidence of
CWD should be excluded from the human food or animal feed chains. Hunters
and wild venison consumers should follow precautionary guidelines available
from the Wisconsin Department of Agriculture, Trade, and Consumer Protection
(http://datcp.state.wi.us/core/consumerinfo) to prevent potential
exposures to the CWD agent.
Fatal Degenerative Neurologic Illnesses in Men Who Participated in Wild Game Feasts—Wisconsin, 2002. JAMA. 2003;289(11):1369–1371. doi:10.1001/jama.289.11.1369
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