Docs want to check hunters
Study would seek link between brain diseases and
CWD
By Todd Hartman, Rocky Mountain News
August 9, 2002
Neurologists in Denver want to examine hunters from
northeastern Colorado showing early signs of dementia to assess
whether they could have contracted human cases of chronic wasting
disease.
The research, to be overseen by University of Colorado
Health Sciences Center doctors, comes as the state health department
plans to review decades' worth of death records to see if deaths
related to brain diseases are uncommonly high in Colorado's CWD
endemic area.
Patrick Bosque, a neurologist at Denver Health Medical
Center, said it's time to look more directly for patterns linking
CWD with human deaths, because experimental models designed to
answer the question of human susceptibility aren't working well
enough.
"The only way we're going to know is if we see an outbreak
(of dementia-like brain disease in humans) that can be tied back
to deer and elk consumption," said Bosque, whose mice experiments
relating to human risk of CWD are inconclusive.
Looking for cases in the northeastern Colorado endemic area is the
obvious way to go, he said.
"A lot of science comes down to common sense," Bosque
said. "If (CWD) is transmissible, that's where we're going
to see it first."
Bosque said the study involving living hunters and perhaps others
who consumed venison frequently would likely involve mailing letters
to neurologists and primary care clinics, who would refer dementia
patients from northeastern Colorado for a formal evaluation at CU
Health Sciences Center.
Among things neurologists would look for: A pattern of deterioration
similar to other prion diseases. Prions are rogue proteins believed
to be at the root of CWD, mad cow disease, and a related human disease
called Creutzfeldt-Jakob, or CJD.
"We'd want to see something that's getting worse," Bosque
said. "Prion diseases progress fairly rapidly; they're not
something that progresses over a 10-year period, something on the
order of
a month-to-month, steady worsening."
The long incubation period of prion diseases could make the assessment
more difficult, Bosque said. Someone could have stopped eating venison
decades ago and, in theory at least, show symptoms far later.
Citing a related degenerative disease, called kuru, that struck
tissue-eating cannibals in New Guinea, Bosque said scientists discovered
incubation periods of 30 to 40 years.
The Colorado Department of Public Health and Environment, meanwhile,
is contracting with statisticians at the CU Health Sciences Center
to crunch death records for diagnoses of dementia-like diseases such
as Alzheimer's, Creutzfeldt-Jakob and senility to see if unusually
high numbers of those causes of death appear in northeastern Colorado
compared with rates elsewhere in the state.
State epidemiologist John Pape actually sought the $22,000 study
a year ago, but was initially turned down for funding by the Centers
for Disease Control.
Now, with money in hand, he hopes to see the work completed by early
next year.
"It wouldn't tell us, if we saw higher rates (of brain diseases),
that it was CWD," Pape said. "But it would be a roadmap,
telling us maybe we ought to look at this more, or look at some
of these cases to see what occurred there."
Pape said health officials in Great Britain conducted a similar
analysis - seeking 30 to 40 diagnoses for deaths linked to neurological
diseases - prior to the outbreak of the human form of mad cow disease,
when they were still only wondering if the disease could make the
jump from animals to people. Since then, 135 cases have been documented
in humans. Even so, the early statistical analysis failed to pick
out any glaring patterns.
If the Colorado study did show unusually high death rates from brain
maladies in the endemic area, health officials would have to take
additional steps, including looking at old medical records and talking
to surviving family members.
"It's kind of a crude measure," Pape said. "What
I think it will show is nothing, that people who hunt in those
counties probably don't die of a lot of strange neurological diseases
any
more than people in the southern and western part of the state,
where CWD hasn't occurred."
Hartmant@RockyMountainNews.com
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