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From: TSS ()
Subject: Re: Transmission and adaptation of chronic wasting disease to hamsters and transgenic mice: evidence for strains
Date: April 1, 2007 at 7:30 pm PST

In Reply to: Re: Transmission and adaptation of chronic wasting disease to hamsters and transgenic mice: evidence for strains posted by TSS on March 31, 2007 at 2:04 pm:

>>>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 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.<<<

very disturbing considering the potential for iatrogenic CJD via silent human CWD carriers. ...TSS


Chronic Wasting Disease and Potential Transmission to Humans
Ermias D. Belay,* Ryan A. Maddox,* Elizabeth S. Williams,† Michael W. Miller,‡ Pierluigi Gambetti,§ and Lawrence B. Schonberger*
*Centers for Disease Control and Prevention, Atlanta, Georgia, USA; †University of Wyoming, Laramie, Wyoming, USA; ‡Colorado Division of Wildlife, Fort Collins, Colorado, USA; and §Case Western Reserve University, Cleveland, Ohio, USA

Suggested citation for this article: Belay ED, Maddox RA, Williams ES, Miller MW, Gambetti P, Schonberger LB. Chronic wasting disease and potential transmission to humans. Emerg Infect Dis [serial on the Internet]. 2004 Jun [date cited]. Available from: http://www.cdc.gov/ncidod/EID/vol10no6/03-1082.htm


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Chronic wasting disease (CWD) of deer and elk is endemic in a tri-corner area of Colorado, Wyoming, and Nebraska, and new foci of CWD have been detected in other parts of the United States. Although detection in some areas may be related to increased surveillance, introduction of CWD due to translocation or natural migration of animals may account for some new foci of infection. Increasing spread of CWD has raised concerns about the potential for increasing human exposure to the CWD agent. The foodborne transmission of bovine spongiform encephalopathy to humans indicates that the species barrier may not completely protect humans from animal prion diseases. Conversion of human prion protein by CWD-associated prions has been demonstrated in an in vitro cell-free experiment, but limited investigations have not identified strong evidence for CWD transmission to humans. More epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions.


snip...

Conclusions
The lack of evidence of a link between CWD transmission and unusual cases of CJD, despite several epidemiologic investigations, and the absence of an increase in CJD incidence in Colorado and Wyoming suggest that the risk, if any, of transmission of CWD to humans is low. 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. Studies involving transgenic mice expressing human and cervid prion protein are in progress to further assess the potential for the CWD agent to cause human disease. Epidemiologic studies have also been initiated to identify human cases of prion disease among persons with an increased risk for exposure to potentially CWD-infected deer or elk meat (47). If such cases are identified, laboratory data showing similarities of the etiologic agent to that of the CWD agent would strengthen the conclusion for a causal link. Surveillance for human prion diseases, particularly in areas where CWD has been detected, remains important to effectively monitor the possible transmission of CWD to humans. Because of the long incubation period associated with prion diseases, convincing negative results from epidemiologic and experimental laboratory studies would likely require years of follow-up. In the meantime, to minimize the risk for exposure to the CWD agent, hunters should consult with their state wildlife agencies to identify areas where CWD occurs and continue to follow advice provided by public health and wildlife agencies. Hunters should avoid eating meat from deer and elk that look sick or test positive for CWD. They should wear gloves when field-dressing carcasses, bone-out the meat from the animal, and minimize handling of brain and spinal cord tissues. As a precaution, hunters should avoid eating deer and elk tissues known to harbor the CWD agent (e.g., brain, spinal cord, eyes, spleen, tonsils, lymph nodes) from areas where CWD has been identified.


http://www.cdc.gov/ncidod/EID/vol10no6/03-1082.htm

TSS

JOURNAL OURNAL OF VIROLOGY IROLOGY, Nov. 2005, p. 13794–13796 Vol. 79, No. 21
0022-538X/05/$08.00 !0 doi:10.1128/JVI.79.21.13794–13796.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

NOTES

Interspecies Transmission of Chronic Wasting Disease Prions to
Squirrel Monkeys (Saimiri sciureus sciureus)

Richard F. Marsh, 1† Anthony nthony E. Kincaid, 2 Richard A. Bessen, 3 and Jason C. Bartz Bartz4*
Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison 53706 537061; Department of
Physical Therapy Therapy2 and Department of Medical Microbiology and Immunology, 4 Creighton University, Omaha,
Nebraska 68178; and Department of Veterinary Molecular Biology, Montana
State University, Bozeman, Montana 59718 597183
Received 3 May 2005/Accepted 10 August 2005

Chronic wasting disease (CWD) is an emerging prion disease of deer and elk. The risk of CWD transmission
to humans following exposure to CWD-infected tissues is unknown. To assess the susceptibility of nonhuman
primates to CWD, two squirrel monkeys were inoculated with brain tissue from a CWD-infected mule deer. The
CWD-inoculated squirrel monkeys developed a progressive neurodegenerative disease and were euthanized at
31 and 34 months postinfection. Brain tissue from the CWD-infected squirrel monkeys contained the abnormal
isoform of the prion protein, PrP-res, and displayed spongiform degeneration. This is the first reported
transmission of CWD to primates. ...snip...end

TSS



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