- With the death of the fifth person from CJD, and the
investigation of a sixth since January 2005 in a small area in Idaho, health
authorities are scrambling to figure out why. CJD, the 100% fatal brain
wasting disease, is supposed to be vanishingly rare. Scientists from the
Center for Disease Control (CDC) in Atlanta are puzzled. According to Reuters
(ref 1): "Is what is happening in Idaho an anomaly, a statistical
fluke? That is possible," said Ermias Belay, a top CJD expert with
the CDC who is helping advise officials in Idaho. "But once it exceeds
1.5 or 2 per million, you start asking questions."
-
- Authorities are conducting autopsies to determine if
any of the Idaho victims had variant CJD, the type of CJD definitively
linked with eating mad cows from which over 160 people have died in Britain
and in Europe. If the Idaho autopsy results come back indicating sporadic,
not variant CJD, there will be a collective sigh of relief. After all,
so the conventional wisdom goes, people cannot get sporadic CJD from eating
mad cow infected meat.
-
- But increasingly and distressingly, the science suggests
otherwise. As the months tick by, the science is increasingly highlighting
the possibility that some cases of sporadic CJD might be linked to mad
cow disease. Consider the following facts:
-
- (1) In 2002 a bombshell paper from Professor John Collinge's
research group provoked a stir in academia. The paper showed that genetically
engineered mice, when injected with mad cow disease protein, unexpectedly
produced a molecular profile that closely resembled sporadic CJD, as well
as the expected variant CJD profile (ref 2). Collinge's group is a global
leader in mad cow disease research. They followed up with confirmatory
results in 2004 (ref 3) essentially saying the same thing. The consequence
for humans was that mad cow disease might manifest as BOTH variant and
sporadic CJD. Collinge's research suggests that maybe we should consider
the possibility that some cases of sporadic CJD may arise from eating mad
cow meat. This has implications for the Idaho CJD cluster.
-
- (2) In Europe, new and bizarre forms of mad cow disease
are being discovered as research accelerates. In Italy a new strain of
mad cow disease was announced that bore striking molecular resemblances
to sporadic CJD in humans (ref 4). This new strain was called Bovine Amyloidotic
Spongiform Encephalopathy or BASE. Again the implication from the Italian
research was a link between strains of mad cow disease and sporadic CJD.
Could there be strains of mad cow disease present in the United States,
that give rise to sporadic CJD, for example in the cluster of cases in
Idaho? Nobody knows, because compared with Europe or Japan, only a tiny
percentage of United States cattle are being tested for mad cow disease.
-
- (3) Another angle being explored in Idaho is the possibility
that some of the CJD victims might have eaten venison from chronic wasting
disease (CWD) infected deer. CWD, the brain wasting disease in deer and
elk, is caused by the same deadly prion that causes mad cow disease. CWD
is currently spreading like wildfire through the United States. Can these
deadly prions jump the species barrier to infect cattle or humans? Research
from the United States Agriculture labs in Ames Iowa shows CWD can be transmitted
from deer to cattle (ref 5). A few isolated and worrying cases of young
hunters dying from sporadic CJD have been documented (ref 6), but the CDC
says this was a statistical fluke.
-
- What are the implications of this new scientific research
for the 2005 CJD cluster in Idaho, for the 2004 CJD cluster in Ulster County,
New York and for the New Jersey CJD cluster reported in 2003? The implications
are that we should begin to look beyond variant CJD. We should begin to
face the disturbing possibility that at least some cases of sporadic CJD
in the United States might be caused by consumption of prion contaminated
beef or venison. We should also begin to look for "atypical molecular
CJD patterns, ie new molecular patterns that do not conform to EITHER sporadic
or variant CJD.
-
- Colm Kelleher is the author of Brain Trust: the Hidden
Connection Between Mad Cow and
- Misdiagnosed Alzheimer's Disease. http://www.colmkelleher.com.
He is a senior research scientist in the biotechnology sector.
-
- References
-
- (1) Tanner, Adam (2005). Idaho probes sudden deaths from
rare brain disease. Reuters. August 15, 2005.
- (2) Asante, EA et al (2002). BSE prions propagate as
either variant CJD-like or sporadic CJD-like prion strains in transgenic
mice expressing human prion protein. EMBO Journal, 2002 Dec 2;21(23):6358-66.
- (3) Wadsworth JD et al (2004). Human prion protein with
valine 129 prevents expression of variant CJD phenotype. Science. 2004
Dec 3;306(5702):1793-6. Epub 2004 Nov 11.
- (4) Casalone C et al (2004). Identification of a second
bovine amyloidotic spongiform encephalopathy: molecular similarities with
sporadic Creutzfeldt-Jakob disease. Proc Natl Acad Sci U S A. 2004 Mar
2;101(9):3065-70. Epub 2004 Feb 17.
- (5) Hamir AN et al (2005). Experimental transmission
of chronic wasting disease agent from mule deer to cattle by the intracerebral
route. J Vet Diagn Invest. 2005 May;17(3):276-81.
- (6) Belay ED (2002). Creutzfeldt-Jakob disease in unusually
young patients who consumed venison. Arch Neurol. 2001 Oct;58(10):1673-8.
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