Quotes
(Implications for CWD adaptation to humans? JW)
Nonetheless, the rodent-adapted CWD models we have developed may be useful to experimentally analyze TSE species and strain differences. Despite the low initial attack rate on the first passage of CWD into Sg (Syrian golden) hamsters, CWD derived initially from elk and mule deer readily adapted to hamsters as evidenced by the 100% infection rate on second and third passages. The average incubation periods were similar for the second and third passages, but considerably shorter than the first passage in the Sg hamsters, suggesting that any species barrier to infection (formally, the shortening of incubation period between the first and subsequent passages in a new species) was overcome quickly.
Transmission and adaptation of chronic wasting disease to hamsters and transgenic mice: evidence for strains - Raymond, et al.
Journal of Virology - April 2007 (pdf)
Can humans be infected? I hope not, I am on a short list of folks here at CSU that have, one way or another, become part of an involuntary test group who have accidentally inoculated ourselves. (myself after nearly losing a thumb when taking the brain out of an experimentally infected deer, with a hatchet)
Blog posting by Colorado State University veterinarian - March 2007
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CWD was first recognized in 1967 in captive deer on a Colorado wildlife research facility. It occurs endemically in wild deer in contiguous sections of northcentral Colorado and southeastern Wyoming and episodically on elk farms along the eastern border states of the Rocky Mountains. No disease in humans or other animals has been attributed to CWD, but the potential for disease is very real: infected tissues could be eaten by predators or enjoyed by aficionados of wild game, and carcasses could be rendered for feed that (by error) could find its way to cattle. Regional hunters and elk farmers have been alerted to the risks, but more attention at the national level is urgently needed.
Afterthoughts about Bovine Spongiform
Encephalopathy and Variant Creutzfeldt-Jakob Disease - Paul Brown - June 2001 |
Clearly, it is premature to draw firm conclusions about CWD passing
naturally into humans, cattle and sheep, but the present results suggest
that CWD transmissions to humans would be as limited by PrP incompatibility
as transmissions of BSE or sheep scrapie to humans. Although there is no
evidence that sheep scrapie has affected humans, it is likely that BSE has
caused variant CJD in ~74 people (definite and probable variant CJD cases to
date according to the UK CJD Surveillance Unit). Given the presumably large
number of people exposed to BSE infectivity, the susceptibility of humans
may still be very low compared with cattle, which would be consistent
with the relatively inefficient conversion of human PrP-sen by PrPBSE.
Nonetheless, since humans have apparently been infected by BSE, it would
seem prudent to take reasonable measures to limit exposure of humans (as
well as sheep and cattle) to CWD infectivity as has been recommended for
other animal TSEs.
Evidence of a molecular barrier limiting susceptibility of humans, cattle and sheep to chronic wasting disease - Raymond, et al.
Although the in vitro studies indicating inefficient conversion of human prion protein by CWD-associated prions raise the possibility of low-level transmission of CWD to humans, no human cases of prion disease with strong evidence of a link with CWD have been identified. However, the transmission of BSE to humans and the resulting vCJD indicate that, provided sufficient exposure, the species barrier may not completely protect humans from animal prion diseases. Because CWD has occurred in a limited geographic area for decades, an adequate number of people may not have been exposed to the CWD agent to result in a clinically recognizable human disease. The level and frequency of human exposure to the CWD agent may increase with the spread of CWD in the United States. Because the number of studies seeking evidence for CWD transmission to humans is limited, more epidemiologic and laboratory studies should be conducted to monitor the possibility of such transmissions.
Chronic Wasting Disease and Potential Transmission to Humans - Belay, et al.
Emerging Infectious Diseases - June 2004 (pdf)
"The bottom line is, if we don't tightly control these diseases, we're going to regret it big time" - Dr. Pierluigi Gambetti, director of the National Prion Disease Pathology Surveillance Center
Tracing mad cow to human infection - Case research maps how illness makes cross-species jump
Cleveland Plain Dealer - April 19, 2004
In
2001, the case of a 25-year-old man who reportedly died of a prion disease
after an illness lasting ˜22 months was investigated (Table 2).
Although this man had hunted deer only rarely, his grandfather hunted deer
and elk throughout much of the 1980s and 1990s and regularly shared the
venison with the case-patient's family. The grandfather primarily hunted in
southeastern Wyoming, around the known CWD-endemic area. The case-patient's
illness began with a seizure and progressed to fatigue, poor concentration,
and depression. Memory loss, ataxia, speech abnormalities, combative
behavior, and recurrent seizures also developed. Histopathologic,
immunohistochemical, and Western blot testing of brain autopsy samples
confirmed a prion disease diagnosis. Analysis of the prion protein gene
indicated a P102L mutation coupled with valine at the polymorphic codon 129
in the mutant allele, confirming a diagnosis of
Gerstmann-Sträussler-Scheinker syndrome (GSS). This case-patient was
unusually young even for a person with a GSS P102L mutation. It remains
unknown whether the possible exposure of the case-patient to CWD-infected
venison potentially contributed to the early onset of his prion disease.
Chronic Wasting Disease and Potential Transmission to Humans - Belay, et al.