Research Article
Bayesian Modeling of Prion Disease Dynamics in Mule Deer Using Population
Monitoring and Capture-Recapture Data
Chris Geremia , * E-mail: Chris_Geremia@nps.gov
Affiliation: Natural Resource Ecology Laboratory, Department of Ecosystem
Science and Sustainability and Graduate Degree Program in Ecology, Colorado
State University, Fort Collins, Colorado, United States of America
Current Address: Bison Ecology and Management Office, Wildlife and Aquatic
Resources Branch, Yellowstone Center for Resources, Yellowstone National Park,
National Park Service, Mammoth Hot Springs, WY, United States of America
⨯ Michael W. Miller, Affiliation: Wildlife Health Program, Colorado
Division of Parks and Wildlife, Fort Collins, Colorado, Colorado, United States
of America
⨯ Jennifer A. Hoeting, Affiliation: Department of Statistics, Colorado
State University, Fort Collins, Colorado, United States of America
⨯ Michael F. Antolin, Affiliation: Department of Biology, Colorado State
University, Fort Collins, Colorado, United States of America
⨯ N. Thompson Hobbs Affiliation: Natural Resource Ecology Laboratory,
Department of Ecosystem Science and Sustainability and Graduate Degree Program
in Ecology, Colorado State University, Fort Collins, Colorado, United States of
America
⨯ Bayesian Modeling of Prion Disease Dynamics in Mule Deer Using Population
Monitoring and Capture-Recapture Data Chris Geremia, Michael W. Miller, Jennifer
A. Hoeting, Michael F. Antolin, N. Thompson Hobbs PLOS x Published: October 28,
2015 DOI: 10.1371/journal.pone.0140687
Abstract
Epidemics of chronic wasting disease (CWD) of North American Cervidae have
potential to harm ecosystems and economies. We studied a migratory population of
mule deer (Odocoileus hemionus) affected by CWD for at least three decades using
a Bayesian framework to integrate matrix population and disease models with
long-term monitoring data and detailed process-level studies. We hypothesized
CWD prevalence would be stable or increase between two observation periods
during the late 1990s and after 2010, with higher CWD prevalence making deer
population decline more likely. The weight of evidence suggested a reduction in
the CWD outbreak over time, perhaps in response to intervening harvest-mediated
population reductions. Disease effects on deer population growth under current
conditions were subtle with a 72% chance that CWD depressed population growth.
With CWD, we forecasted a growth rate near one and largely stable deer
population. Disease effects appear to be moderated by timing of infection,
prolonged disease course, and locally variable infection. Long-term outcomes
will depend heavily on whether current conditions hold and high prevalence
remains a localized phenomenon.
Discussion
The epidemic dynamics of CWD and its consequences for deer populations in
northern Colorado and elsewhere will play out over the coming decades, well
beyond the duration of any single field campaign or surveillance period. Our
5-year study was too brief to measure temporal trends. Moreover, historical data
were incomplete with respect to estimating infection probability. Such
challenges are commonly faced by those attempting to understand complex disease
or other ecological processes that operate on protracted time scales. In this
case, however, our Bayesian hierarchical approach, which integrated a matrix
population and disease model with available monitoring data and process level
data from contemporary capture-recapture efforts, yielded readily-interpreted
estimates of key epidemic parameters despite the collective shortcomings in
available data. Our approach allowed for forecasts of population and disease
conditions that are far more revealing than simulation models that would
traditionally be relied upon to gain such insights.
Our approach provides a framework for beginning to assess the effect of CWD
on deer populations and yields parameter estimates and short term forecasts that
include uncertainty via predictive process distributions. In the areas we
studied, CWD did not lower population growth rate to a degree sufficient to
precipitate a rapid, catastrophic decline in deer abundance. Instead, the
effects on growth appear to have remained subtle despite CWD having been present
for decades. Estimated growth rate under the current level of infection centered
near one.
Prion infection can be thought of as accelerating the time of demise for
infected individuals. Disease moves deer into demographic stage equivalent to
senescence, characterized by the progressively lower survival and reproduction
seen in aged individuals. Moving large numbers of young deer into
"disease-related senescence" could have debilitating effects on population
growth, as reflected in the dynamics of unchecked CWD epidemics described in
captive deer herds [17]. However, under the regimen of natural and prescribed
controls operating on herds we studied infection rates were relatively constant
between 1.5 and 8.5 years of age. The average life expectancy of CWD-free deer
was 5.39 (4.23−6.91) years and most (9 of 15) new infections occurred in deer
≥5.5 years old. Such timing of onset, combined with the slow progression of
disease, likely muted the effects of CWD on population growth. Furthermore,
infection was spatially localized: annual infection probability varied by an
order of magnitude across a relatively short distance, such that overall an
insufficient number of deer were becoming infected to cause rapid and widespread
population collapse within the timeframe of our study.
Regardless of short-term trends and its ultimate fate, the deer population
is clearly less robust with CWD. Deer abundance has declined since the 1980s
(Fig 2) [27]. We cannot be sure of the ultimate cause of decline, because the
deer population has been subject to changing practices to manage population
demographics and CWD [27], in the face of other disease outbreaks (such as
hemorrhagic disease), habitat fragmentation and a changing climate [1,28–29]. We
estimated that the current population (with prevalence near 4%) is stable, and
we cannot rule out slow increases or declines in abundance. Declining numbers
would be the expected outcome if prevalence levels resembled those measured in
this population during the late 1990s. Thus, CWD, under high prevalence, may
have been an important contributing cause to the decline observed during the
1980s and 90s (Fig 6).
Managers have attempted to promote population growth by essentially ceasing
female harvest since 2006 [27]. While the Cherokee Park subpopulation has
responded with slow growth, small, if any, increases have been detected in the
Red Mountain and Big Hole subpopulations where CWD prevalence exceeds 5%.
Management of deer populations throughout the world typically includes some
degree of female harvest. Even under low CWD prevalence, CWD appears to affect
population growth sufficiently to make annual harvest (of females) an
unsustainable management practice.
Our mark-recapture study coincided with a period of historically low deer
abundance, and thus we expected higher growth rates than observed. Such
discrepancy suggests that we may have underestimated CWD’s direct or indirect
effects. Average adult survival for susceptible female deer was 0.82
(0.77−0.86), which centered below the range-wide average of 0.85 [20,30]. The
difference between susceptible and infected deer survival was therefore less
than would be expected if susceptible deer survival was nearer to or above the
range-wide average, as might be expected in a low-density population.
Population growth rates in the absence of CWD were lowest in Red Mountain
and Big Hole, which corresponded to highest local disease prevalence. Apparent
competition is an indirect interaction among prey species mediated by a shared
predator [31–32]. Mountain lions prey selectively on CWD infected deer [33] and
CWD could result in an abundance of vulnerable prey, thereby enhancing mountain
lion survival and reproduction [20]. A resulting outcome could be increased
predation on uninfected deer and overall depression of the deer population–the
inverse relationship between CWD prevalence and survival of uninfected deer
supports the possibility of indirect disease effects on population growth.
The effect of CWD partly depended on the scale of analysis. When all data
were combined, we did not find the remarkably high prevalence observed in two
more localized deer populations (< 600 individuals) studied elsewhere. Mule
deer in the Table Mesa population in northcentral Colorado exhibited ~20%
prevalence among adult females with average annual infection probability of 0.23
[20]. Similarly, 42% of female white-tailed deer developed CWD during a seven
year study of the Deer Creek population in central Wyoming [18]. The Table Mesa
and Deer Creek populations declined and CWD was implicated as an ultimate or
contributing cause [18– 20]. Annual infection probabilities approached such
levels only within highly localized portions (< 50 km2) of our study area,
and decline was the more likely scenario in associated herd units (Red Mountain
and Big Hole). However, those local declines appear to be offset by growth in
nearby herd units with lower infection rates. The net outcome becomes largely
unchanging overall deer abundance under the conditions currently operating on
these different herd units.
It follows that the long-term outcomes of CWD may depend heavily on whether
high prevalence remains a localized phenomenon. CWD-causing prions appear to
persist locally by transmission among individuals and from environmental
reservoirs, but spatial spread almost certainly requires transport among
spatially-distinct social units [16,34]. Deer show extraordinary fidelity to
their female social groups and home ranges established early in life. This may
limit prion mobility and thereby afford deer some natural “spatial resistance”
against CWD on a larger geographic scale. However, overlap between migrant
groups on summer range could bridge these social barriers, as previously
suggested for the heavily infected Red Mountain herd unit [34]. Although not
studied in depth here, male mule deer have larger home ranges [35], higher
infection rates [20,24], and less fidelity to specific social groups [35]. Males
could serve as a pathway of infection among bands of females as the males seek
mates [34,35].
The long-term outcomes of CWD will depend on the extent to which this
outbreak increases beyond what we observed. The weight of evidence suggests that
the CWD outbreak is less severe today than during the late 1990s (and early
2000s). We cannot be sure that the 1997–2001 and 2010–2014 prevalence estimates
are directly comparable. The early data were post mortem tests of harvested or
culled deer and the later data were live tests of randomly chosen helicopter
captured deer. Ages of sampled deer [36,37], increased vulnerability of infected
deer to harvest [38], prion precursor genotype of sampled deer [39], and testing
diagnostic method [40] may have influenced prevalence estimates. But, the
magnitude of difference in prevalence estimates among time periods is likely
greater than would be explained by sampling effects alone.
To date, we are unaware of a study that documents a decrease in CWD
prevalence over time in mule deer, white-tailed deer or elk. We briefly consider
three plausible explanations for our findings: a) that natural oscillations
occur in CWD outbreaks; b) that the outbreak has peaked and is declining to a
lower endemic level; or c) that previous management actions were more successful
at suppressing the outbreak than originally believed.
Sharp & Pastor [41] illustrated that CWD outbreaks may play out as a
series of reoccurring epidemics characterized by either stable limit cycles or
oscillations that may dampen or amplify as a function of deer density. If this
is the case, we would expect today’s declining deer population to feedback on
conditions–lowering transmission rates leading to reduced CWD effects and a
growing population. Increasing abundance would support higher transmission
rates, deer decline, and oscillations of CWD prevalence and deer. Alternatively,
Almberg et al. [21] (see also [22–24,41,42]) suggested that CWD outbreaks could
reach endemic equilibrium characterized by coexistence of a smaller deer
population and CWD. Under these scenarios, population prevalence would reach a
lower, constant level after a period of high prevalence and deer decline.
Although neither of the foregoing scenarios can be dismissed completely,
invoking them ignores the extensive management of this deer population that
occurred in the years between the two time points we chose as the basis for our
analyses. Management aimed to reduce CWD transmission between 2000 and 2005,
which included a combination of (crude and unpopular) focal culling and a
broader increase in female harvest, decreased overall deer abundance by about
25%. Analyses carried out shortly after suggested that reductions in deer
density had made little impact on CWD prevalence [10]. However, our current
findings suggest that these management actions may indeed have attenuated the
outbreak. Observed dynamics over the last decade closely approximate those
predicted from models by Wild et al. [42] that included a substantial amount of
selective predation on CWD-infected individuals. That harvest could be a source
of selective mortality is supported by an early notion that CWD-infected deer
might be more vulnerable to harvest [43], just as infected deer also appear to
be more vulnerable to vehicle collisions and predation [20,33,44]. This offers
the possibility that hunting could be used as a more tightly controlled
substitute for predation in studies of system responses with CWD and perhaps
other similar diseases.
The protracted time-scale of the CWD outbreak is much longer than the
timespan of our research, which limits our ability to identify the true
explanation of our findings. Nonetheless, our research suggests that, at least
for the foreseeable future (e.g., decades), mule deer populations sharing the
overall survival and infection probabilities estimated from our analyses may
persist but likely will not thrive where CWD becomes established as an endemic
infectious disease.
‘’Nonetheless, our research suggests that, at least for the foreseeable
future (e.g., decades), mule deer populations sharing the overall survival and
infection probabilities estimated from our analyses may persist but likely will
not thrive where CWD becomes established as an endemic infectious disease. ‘’
*** Bayesian Modeling of Prion Disease Dynamics in Mule Deer Using
Population Monitoring and Capture-Recapture Data
‘’Mountain lions prey selectively on CWD infected deer [33] and CWD could
result in an abundance of vulnerable prey, thereby enhancing mountain lion
survival and reproduction [20].’’
please see ;
‘’preliminary results suggesting that bobcats (Lynx rufus) may be
susceptible to white-tailed deer (Odocoileus virginianus) chronic wasting
disease agent.’’
references on Feline Spongiform Encephalopathy FSE toward the bottom, see
;
Assessing Transmissible Spongiform Encephalopathy Species Barriers with an
In Vitro Prion Protein Conversion Assay
Tuesday, December 15, 2015
Chronic Wasting Disease will cause a Wyoming deer herd to go virtually
extinct in 41 years, a five-year study predicts
Study: Chronic Wasting Disease kills 19% of deer herd annually
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
***Title: Transmission of chronic wasting disease to sentinel reindeer
(Rangifer tarandus tarandus)
Authors
item Moore, S - item Kunkle, Robert item Nicholson, Eric item Richt,
Juergen item Hamir, Amirali item Waters, Wade item Greenlee, Justin
Submitted to: American College of Veterinary Pathologists Meeting
Publication Type: Abstract Only Publication Acceptance Date: August 12, 2015
Publication Date: N/A
Technical Abstract: Chronic wasting disease (CWD) is a naturally-occurring,
fatal neurodegenerative disease of North American cervids. Reindeer (Rangifer
tarandus tarandus) are susceptible to CWD following oral challenge, but CWD has
not been reported in free-ranging caribou (Rangifer tarandus caribou) or farmed
reindeer. Potential contact between CWD-affected cervids and Rangifer species
that are free-ranging or co-housed on farms presents a potential risk of CWD
transmission. The aims of this study were to 1) investigate the transmission of
CWD from white-tailed deer (Odocoileus virginianus; CWD-wtd), mule deer
(Odocoileus hemionus; CWD-md), or elk (Cervus elaphus nelsoni; CWD-elk) to
reindeer via the intracranial route, and 2) to assess for direct and indirect
horizontal transmission to non-inoculated sentinels. Three groups of 5 reindeer
fawns were challenged intracranially with CWD-wtd, CWD-md, or CWD-elk. Two years
after challenge of inoculated reindeer, non-inoculated control reindeer were
introduced into the same pen as the CWD-wtd inoculated reindeer (n=4) or into a
pen adjacent to the CWD-md inoculated reindeer (n=2). Reindeer were allowed to
develop clinical disease. At death/euthanasia a complete necropsy examination
was performed, including immunohistochemical testing of tissues for
disease-associated CWD prion protein (PrP-CWD). Intracranially challenged
reindeer developed clinical disease from 21 months post-inoculation (MPI).
PrP-CWD was detected in 5/6 sentinel reindeer although only 2/6 developed
clinical disease during the study period (<57 div="" mpi="">
***We have shown that reindeer are susceptible to CWD from various cervid
sources and can transmit CWD to naive reindeer both directly and indirectly.
Last Modified: 12/3/2015
***PrP-CWD was detected in 5/6 sentinel reindeer although only 2/6
developed clinical disease during the study period (<57 div="" mpi="">
***We have shown that reindeer are susceptible to CWD from various cervid
sources and can transmit CWD to naive reindeer both directly and indirectly.
Tuesday, September 29, 2015
*** Transmission of chronic wasting disease to sentinel reindeer (Rangifer
tarandus tarandus) can transmit CWD to naive reindeer both directly and
indirectly
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
*** Infectious agent of sheep scrapie may persist in the environment for at
least 16 years ***
Gudmundur Georgsson1, Sigurdur Sigurdarson2 and Paul Brown3
*** Spraker suggested an interesting explanation for the occurrence of CWD.
The deer pens at the Foot Hills Campus were built some 30-40 years ago by a Dr.
Bob Davis. At or abut that time, allegedly, some scrapie work was conducted at
this site. When deer were introduced to the pens they occupied ground that had
previously been occupied by sheep.
HIGHEST INFECTION RATE ON SEVERAL CWD CONFIRMED CAPTIVES
CHRONIC WASTING DISEASE CWD WISCONSIN Almond Deer (Buckhorn Flats) Farm
Update DECEMBER 2011
The CWD infection rate was nearly 80%, the highest ever in a North American
captive herd.
RECOMMENDATION: That the Board approve the purchase of 80 acres of land for
$465,000 for the Statewide Wildlife Habitat Program in Portage County and
approve the restrictions on public use of the site.
SUMMARY:
For Immediate Release Thursday, October 2, 2014
Dustin Vande Hoef 515/281-3375 or 515/326-1616 (cell) or
Dustin.VandeHoef@IowaAgriculture.gov
*** TEST RESULTS FROM CAPTIVE DEER HERD WITH CHRONIC WASTING DISEASE
RELEASED 79.8 percent of the deer tested positive for the disease
DES MOINES – The Iowa Department of Agriculture and Land Stewardship today
announced that the test results from the depopulation of a quarantined captive
deer herd in north-central Iowa showed that 284 of the 356 deer, or 79.8% of the
herd, tested positive for Chronic Wasting Disease (CWD).
*** see history of this CWD blunder here ;
On June 5, 2013, DNR conducted a fence inspection, after gaining approval
from surrounding landowners, and confirmed that the fenced had been cut or
removed in at least four separate locations; that the fence had degraded and was
failing to maintain the enclosure around the Quarantined Premises in at least
one area; that at least three gates had been opened;and that deer tracks were
visible in and around one of the open areas in the sand on both sides of the
fence, evidencing movement of deer into the Quarantined Premises.
The overall incidence of clinical CWD in white-tailed deer was 82%
Species (cohort) CWD (cases/total) Incidence (%) Age at CWD death (mo)
”The occurrence of CWD must be viewed against the contest of the locations
in which it occurred. It was an incidental and unwelcome complication of the
respective wildlife research programmes. Despite it’s subsequent recognition as
a new disease of cervids, therefore justifying direct investigation, no specific
research funding was forthcoming. The USDA veiwed it as a wildlife problem and
consequently not their province!” page 26.
Sunday, January 06, 2013
USDA TO PGC ONCE CAPTIVES ESCAPE
*** "it‘s no longer its business.”
CWD, spreading it around...
for the game farm industry, and their constituents, to continue to believe
that they are _NOT_, and or insinuate that they have _NEVER_ been part of the
problem, will only continue to help spread cwd. the game farming industry, from
the shooting pens, to the urine mills, the antler mills, the sperm mills, velvet
mills, shooting pens, to large ranches, are not the only problem, but it is
painfully obvious that they have been part of the problem for decades and
decades, just spreading it around, as with transportation and or exportation and
or importation of cervids from game farming industry, and have been proven to
spread cwd. no one need to look any further than South Korea blunder ;
===========================================
spreading cwd around...
Between 1996 and 2002, chronic wasting disease was diagnosed in 39 herds of
farmed elk in Saskatchewan in a single epidemic. All of these herds were
depopulated as part of the Canadian Food Inspection Agency’s (CFIA) disease
eradication program. Animals, primarily over 12 mo of age, were tested for the
presence CWD prions following euthanasia. Twenty-one of the herds were linked
through movements of live animals with latent CWD from a single infected source
herd in Saskatchewan, 17 through movements of animals from 7 of the secondarily
infected herds.
***The source herd is believed to have become infected via importation of
animals from a game farm in South Dakota where CWD was subsequently diagnosed
(7,4). A wide range in herd prevalence of CWD at the time of herd depopulation
of these herds was observed. Within-herd transmission was observed on some
farms, while the disease remained confined to the introduced animals on other
farms.
spreading cwd around...
Friday, May 13, 2011
Chronic Wasting Disease (CWD) outbreaks and surveillance program in the
Republic of Korea
Hyun-Joo Sohn, Yoon-Hee Lee, Min-jeong Kim, Eun-Im Yun, Hyo-Jin Kim,
Won-Yong Lee, Dong-Seob Tark, In- Soo Cho, Foreign Animal Disease Research
Division, National Veterinary Research and Quarantine Service, Republic of Korea
Chronic wasting disease (CWD) has been recognized as an important prion
disease in native North America deer and Rocky mountain elks. The disease is a
unique member of the transmissible spongiform encephalopathies (TSEs), which
naturally affects only a few species. CWD had been limited to USA and Canada
until 2000.
On 28 December 2000, information from the Canadian government showed that a
total of 95 elk had been exported from farms with CWD to Korea. These consisted
of 23 elk in 1994 originating from the so-called “source farm” in Canada, and 72
elk in 1997, which had been held in pre export quarantine at the “source
farm”.Based on export information of CWD suspected elk from Canada to Korea, CWD
surveillance program was initiated by the Ministry of Agriculture and Forestry
(MAF) in 2001.
All elks imported in 1997 were traced back, however elks imported in 1994
were impossible to identify. CWD control measures included stamping out of all
animals in the affected farm, and thorough cleaning and disinfection of the
premises. In addition, nationwide clinical surveillance of Korean native
cervids, and improved measures to ensure reporting of CWD suspect cases were
implemented.
Total of 9 elks were found to be affected. CWD was designated as a
notifiable disease under the Act for Prevention of Livestock Epidemics in 2002.
Additional CWD cases - 12 elks and 2 elks - were diagnosed in 2004 and
2005.
Since February of 2005, when slaughtered elks were found to be positive,
all slaughtered cervid for human consumption at abattoirs were designated as
target of the CWD surveillance program. Currently, CWD laboratory testing is
only conducted by National Reference Laboratory on CWD, which is the Foreign
Animal Disease Division (FADD) of National Veterinary Research and Quarantine
Service (NVRQS).
In July 2010, one out of 3 elks from Farm 1 which were slaughtered for the
human consumption was confirmed as positive. Consequently, all cervid – 54 elks,
41 Sika deer and 5 Albino deer – were culled and one elk was found to be
positive. Epidemiological investigations were conducted by Veterinary
Epidemiology Division (VED) of NVRQS in collaboration with provincial veterinary
services.
Epidemiologically related farms were found as 3 farms and all cervid at
these farms were culled and subjected to CWD diagnosis. Three elks and 5
crossbreeds (Red deer and Sika deer) were confirmed as positive at farm 2.
All cervids at Farm 3 and Farm 4 – 15 elks and 47 elks – were culled and
confirmed as negative.
Further epidemiological investigations showed that these CWD outbreaks were
linked to the importation of elks from Canada in 1994 based on circumstantial
evidences.
In December 2010, one elk was confirmed as positive at Farm 5.
Consequently, all cervid – 3 elks, 11 Manchurian Sika deer and 20 Sika deer –
were culled and one Manchurian Sika deer and seven Sika deer were found to be
positive. This is the first report of CWD in these sub-species of deer.
Epidemiological investigations found that the owner of the Farm 2 in CWD
outbreaks in July 2010 had co-owned the Farm 5.
In addition, it was newly revealed that one positive elk was introduced
from Farm 6 of Jinju-si Gyeongsang Namdo. All cervid – 19 elks, 15 crossbreed
(species unknown) and 64 Sika deer – of Farm 6 were culled, but all confirmed as
negative.
New studies on the heat resistance of hamster-adapted scrapie agent:
Threshold survival after ashing at 600°C suggests an inorganic template of
replication
The infectious agents responsible for transmissible spongiform
encephalopathy (TSE) are notoriously resistant to most physical and chemical
methods used for inactivating pathogens, including heat. It has long been
recognized, for example, that boiling is ineffective and that higher
temperatures are most efficient when combined with steam under pressure (i.e.,
autoclaving). As a means of decontamination, dry heat is used only at the
extremely high temperatures achieved during incineration, usually in excess of
600°C. It has been assumed, without proof, that incineration totally inactivates
the agents of TSE, whether of human or animal origin.
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel
Production
Histochemical analysis of hamster brains inoculated with the solid residue
showed typical spongiform degeneration and vacuolation. Re-inoculation of these
brains into a new cohort of hamsters led to onset of clinical scrapie symptoms
within 75 days, suggesting that the specific infectivity of the prion protein
was not changed during the biodiesel process. The biodiesel reaction cannot be
considered a viable prion decontamination method for MBM, although we observed
increased survival time of hamsters and reduced infectivity greater than 6 log
orders in the solid MBM residue. Furthermore, results from our study compare for
the first time prion detection by Western Blot versus an infectivity bioassay
for analysis of biodiesel reaction products. We could show that biochemical
analysis alone is insufficient for detection of prion infectivity after a
biodiesel process.
Detection of protease-resistant cervid prion protein in water from a
CWD-endemic area
The data presented here demonstrate that sPMCA can detect low levels of
PrPCWD in the environment, corroborate previous biological and experimental data
suggesting long term persistence of prions in the environment2,3 and imply that
PrPCWD accumulation over time may contribute to transmission of CWD in areas
where it has been endemic for decades. This work demonstrates the utility of
sPMCA to evaluate other environmental water sources for PrPCWD, including
smaller bodies of water such as vernal pools and wallows, where large numbers of
cervids congregate and into which prions from infected animals may be shed and
concentrated to infectious levels.
A Quantitative Assessment of the Amount of Prion Diverted to Category 1
Materials and Wastewater During Processing
Keywords:Abattoir;bovine spongiform encephalopathy;QRA;scrapie;TSE
In this article the development and parameterization of a quantitative
assessment is described that estimates the amount of TSE infectivity that is
present in a whole animal carcass (bovine spongiform encephalopathy [BSE] for
cattle and classical/atypical scrapie for sheep and lambs) and the amounts that
subsequently fall to the floor during processing at facilities that handle
specified risk material (SRM). BSE in cattle was found to contain the most oral
doses, with a mean of 9864 BO ID50s (310, 38840) in a whole carcass compared to
a mean of 1851 OO ID50s (600, 4070) and 614 OO ID50s (155, 1509) for a sheep
infected with classical and atypical scrapie, respectively. Lambs contained the
least infectivity with a mean of 251 OO ID50s (83, 548) for classical scrapie
and 1 OO ID50s (0.2, 2) for atypical scrapie. The highest amounts of infectivity
falling to the floor and entering the drains from slaughtering a whole carcass
at SRM facilities were found to be from cattle infected with BSE at rendering
and large incineration facilities with 7.4 BO ID50s (0.1, 29), intermediate
plants and small incinerators with a mean of 4.5 BO ID50s (0.1, 18), and
collection centers, 3.6 BO ID50s (0.1, 14). The lowest amounts entering drains
are from lambs infected with classical and atypical scrapie at intermediate
plants and atypical scrapie at collection centers with a mean of 3 × 10−7 OO
ID50s (2 × 10−8, 1 × 10−6) per carcass. The results of this model provide key
inputs for the model in the companion paper published here.
PL1
Using in vitro prion replication for high sensitive detection of prions and
prionlike proteins and for understanding mechanisms of transmission.
Claudio Soto
Mitchell Center for Alzheimer's diseases and related Brain disorders,
Department of Neurology, University of Texas Medical School at Houston.
Prion and prion-like proteins are misfolded protein aggregates with the
ability to selfpropagate to spread disease between cells, organs and in some
cases across individuals. I n T r a n s m i s s i b l e s p o n g i f o r m
encephalopathies (TSEs), prions are mostly composed by a misfolded form of the
prion protein (PrPSc), which propagates by transmitting its misfolding to the
normal prion protein (PrPC). The availability of a procedure to replicate prions
in the laboratory may be important to study the mechanism of prion and
prion-like spreading and to develop high sensitive detection of small quantities
of misfolded proteins in biological fluids, tissues and environmental samples.
Protein Misfolding Cyclic Amplification (PMCA) is a simple, fast and efficient
methodology to mimic prion replication in the test tube. PMCA is a platform
technology that may enable amplification of any prion-like misfolded protein
aggregating through a seeding/nucleation process. In TSEs, PMCA is able to
detect the equivalent of one single molecule of infectious PrPSc and propagate
prions that maintain high infectivity, strain properties and species
specificity. Using PMCA we have been able to detect PrPSc in blood and urine of
experimentally infected animals and humans affected by vCJD with high
sensitivity and specificity. Recently, we have expanded the principles of PMCA
to amplify amyloid-beta (Aβ) and alphasynuclein (α-syn) aggregates implicated in
Alzheimer's and Parkinson's diseases, respectively. Experiments are ongoing to
study the utility of this technology to detect Aβ and α-syn aggregates in
samples of CSF and blood from patients affected by these diseases.
=========================
***Recently, we have been using PMCA to study the role of environmental
prion contamination on the horizontal spreading of TSEs. These experiments have
focused on the study of the interaction of prions with plants and
environmentally relevant surfaces. Our results show that plants (both leaves and
roots) bind tightly to prions present in brain extracts and excreta (urine and
feces) and retain even small quantities of PrPSc for long periods of time.
Strikingly, ingestion of prioncontaminated leaves and roots produced disease
with a 100% attack rate and an incubation period not substantially longer than
feeding animals directly with scrapie brain homogenate. Furthermore, plants can
uptake prions from contaminated soil and transport them to different parts of
the plant tissue (stem and leaves). Similarly, prions bind tightly to a variety
of environmentally relevant surfaces, including stones, wood, metals, plastic,
glass, cement, etc. Prion contaminated surfaces efficiently transmit prion
disease when these materials were directly injected into the brain of animals
and strikingly when the contaminated surfaces were just placed in the animal
cage. These findings demonstrate that environmental materials can efficiently
bind infectious prions and act as carriers of infectivity, suggesting that they
may play an important role in the horizontal transmission of the disease.
========================
Since its invention 13 years ago, PMCA has helped to answer fundamental
questions of prion propagation and has broad applications in research areas
including the food industry, blood bank safety and human and veterinary disease
diagnosis.
see ;
Wednesday, December 16, 2015
Objects in contact with classical scrapie sheep act as a reservoir for
scrapie transmission
Objects in contact with classical scrapie sheep act as a reservoir for
scrapie transmission
Timm Konold1*, Stephen A. C. Hawkins2, Lisa C. Thurston3, Ben C. Maddison4,
Kevin C. Gough5, Anthony Duarte1 and Hugh A. Simmons1
1 Animal Sciences Unit, Animal and Plant Health Agency Weybridge,
Addlestone, UK, 2 Pathology Department, Animal and Plant Health Agency
Weybridge, Addlestone, UK, 3 Surveillance and Laboratory Services, Animal and
Plant Health Agency Penrith, Penrith, UK, 4 ADAS UK, School of Veterinary
Medicine and Science, University of Nottingham, Sutton Bonington, UK, 5 School
of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington,
UK
Classical scrapie is an environmentally transmissible prion disease of
sheep and goats. Prions can persist and remain potentially infectious in the
environment for many years and thus pose a risk of infecting animals after
re-stocking. In vitro studies using serial protein misfolding cyclic
amplification (sPMCA) have suggested that objects on a scrapie affected sheep
farm could contribute to disease transmission. This in vivo study aimed to
determine the role of field furniture (water troughs, feeding troughs, fencing,
and other objects that sheep may rub against) used by a scrapie-infected sheep
flock as a vector for disease transmission to scrapie-free lambs with the prion
protein genotype VRQ/VRQ, which is associated with high susceptibility to
classical scrapie. When the field furniture was placed in clean accommodation,
sheep became infected when exposed to either a water trough (four out of five)
or to objects used for rubbing (four out of seven). This field furniture had
been used by the scrapie-infected flock 8 weeks earlier and had previously been
shown to harbor scrapie prions by sPMCA. Sheep also became infected (20 out of
23) through exposure to contaminated field furniture placed within pasture not
used by scrapie-infected sheep for 40 months, even though swabs from this
furniture tested negative by PMCA. This infection rate decreased (1 out of 12)
on the same paddock after replacement with clean field furniture. Twelve grazing
sheep exposed to field furniture not in contact with scrapie-infected sheep for
18 months remained scrapie free. The findings of this study highlight the role
of field furniture used by scrapie-infected sheep to act as a reservoir for
disease re-introduction although infectivity declines considerably if the field
furniture has not been in contact with scrapie-infected sheep for several
months. PMCA may not be as sensitive as VRQ/VRQ sheep to test for environmental
contamination.
snip...
Discussion
Classical scrapie is an environmentally transmissible disease because it
has been reported in naïve, supposedly previously unexposed sheep placed in
pastures formerly occupied by scrapie-infected sheep (4, 19, 20). Although the
vector for disease transmission is not known, soil is likely to be an important
reservoir for prions (2) where – based on studies in rodents – prions can adhere
to minerals as a biologically active form (21) and remain infectious for more
than 2 years (22). Similarly, chronic wasting disease (CWD) has re-occurred in
mule deer housed in paddocks used by infected deer 2 years earlier, which was
assumed to be through foraging and soil consumption (23).
Our study suggested that the risk of acquiring scrapie infection was
greater through exposure to contaminated wooden, plastic, and metal surfaces via
water or food troughs, fencing, and hurdles than through grazing. Drinking from
a water trough used by the scrapie flock was sufficient to cause infection in
sheep in a clean building. Exposure to fences and other objects used for rubbing
also led to infection, which supported the hypothesis that skin may be a vector
for disease transmission (9). The risk of these objects to cause infection was
further demonstrated when 87% of 23 sheep presented with PrPSc in lymphoid
tissue after grazing on one of the paddocks, which contained metal hurdles, a
metal lamb creep and a water trough in contact with the scrapie flock up to 8
weeks earlier, whereas no infection had been demonstrated previously in sheep
grazing on this paddock, when equipped with new fencing and field furniture.
When the contaminated furniture and fencing were removed, the infection rate
dropped significantly to 8% of 12 sheep, with soil of the paddock as the most
likely source of infection caused by shedding of prions from the
scrapie-infected sheep in this paddock up to a week earlier.
This study also indicated that the level of contamination of field
furniture sufficient to cause infection was dependent on two factors: stage of
incubation period and time of last use by scrapie-infected sheep. Drinking from
a water trough that had been used by scrapie sheep in the predominantly
pre-clinical phase did not appear to cause infection, whereas infection was
shown in sheep drinking from the water trough used by scrapie sheep in the later
stage of the disease. It is possible that contamination occurred through
shedding of prions in saliva, which may have contaminated the surface of the
water trough and subsequently the water when it was refilled. Contamination
appeared to be sufficient to cause infection only if the trough was in contact
with sheep that included clinical cases. Indeed, there is an increased risk of
bodily fluid infectivity with disease progression in scrapie (24) and CWD (25)
based on PrPSc detection by sPMCA. Although ultraviolet light and heat under
natural conditions do not inactivate prions (26), furniture in contact with the
scrapie flock, which was assumed to be sufficiently contaminated to cause
infection, did not act as vector for disease if not used for 18 months, which
suggest that the weathering process alone was sufficient to inactivate prions.
PrPSc detection by sPMCA is increasingly used as a surrogate for
infectivity measurements by bioassay in sheep or mice. In this reported study,
however, the levels of PrPSc present in the environment were below the limit of
detection of the sPMCA method, yet were still sufficient to cause infection of
in-contact animals. In the present study, the outdoor objects were removed from
the infected flock 8 weeks prior to sampling and were positive by sPMCA at very
low levels (2 out of 37 reactions). As this sPMCA assay also yielded 2 positive
reactions out of 139 in samples from the scrapie-free farm, the sPMCA assay
could not detect PrPSc on any of the objects above the background of the assay.
False positive reactions with sPMCA at a low frequency associated with de novo
formation of infectious prions have been reported (27, 28). This is in contrast
to our previous study where we demonstrated that outdoor objects that had been
in contact with the scrapie-infected flock up to 20 days prior to sampling
harbored PrPSc that was detectable by sPMCA analysis [4 out of 15 reactions
(12)] and was significantly more positive by the assay compared to analogous
samples from the scrapie-free farm. This discrepancy could be due to the use of
a different sPMCA substrate between the studies that may alter the efficiency of
amplification of the environmental PrPSc. In addition, the present study had a
longer timeframe between the objects being in contact with the infected flock
and sampling, which may affect the levels of extractable PrPSc. Alternatively,
there may be potentially patchy contamination of this furniture with PrPSc,
which may have been missed by swabbing. The failure of sPMCA to detect
CWD-associated PrP in saliva from clinically affected deer despite confirmation
of infectivity in saliva-inoculated transgenic mice was associated with as yet
unidentified inhibitors in saliva (29), and it is possible that the sensitivity
of sPMCA is affected by other substances in the tested material. In addition,
sampling of amplifiable PrPSc and subsequent detection by sPMCA may be more
difficult from furniture exposed to weather, which is supported by the
observation that PrPSc was detected by sPMCA more frequently in indoor than
outdoor furniture (12). A recent experimental study has demonstrated that
repeated cycles of drying and wetting of prion-contaminated soil, equivalent to
what is expected under natural weathering conditions, could reduce PMCA
amplification efficiency and extend the incubation period in hamsters inoculated
with soil samples (30). This seems to apply also to this study even though the
reduction in infectivity was more dramatic in the sPMCA assays than in the sheep
model. Sheep were not kept until clinical end-point, which would have enabled us
to compare incubation periods, but the lack of infection in sheep exposed to
furniture that had not been in contact with scrapie sheep for a longer time
period supports the hypothesis that prion degradation and subsequent loss of
infectivity occurs even under natural conditions.
In conclusion, the results in the current study indicate that removal of
furniture that had been in contact with scrapie-infected animals should be
recommended, particularly since cleaning and decontamination may not effectively
remove scrapie infectivity (31), even though infectivity declines considerably
if the pasture and the field furniture have not been in contact with
scrapie-infected sheep for several months. As sPMCA failed to detect PrPSc in
furniture that was subjected to weathering, even though exposure led to
infection in sheep, this method may not always be reliable in predicting the
risk of scrapie infection through environmental contamination. These results
suggest that the VRQ/VRQ sheep model may be more sensitive than sPMCA for the
detection of environmentally associated scrapie, and suggest that extremely low
levels of scrapie contamination are able to cause infection in susceptible sheep
genotypes.
Keywords: classical scrapie, prion, transmissible spongiform
encephalopathy, sheep, field furniture, reservoir, serial protein misfolding
cyclic amplification
Wednesday, December 16, 2015
*** Objects in contact with classical scrapie sheep act as a reservoir for
scrapie transmission ***
Circulation of prions within dust on a scrapie affected farm
Kevin C Gough1, Claire A Baker2, Hugh A Simmons3, Steve A Hawkins3 and Ben
C Maddison2*
Abstract
Prion diseases are fatal neurological disorders that affect humans and
animals. Scrapie of sheep/goats and Chronic Wasting Disease (CWD) of deer/elk
are contagious prion diseases where environmental reservoirs have a direct link
to the transmission of disease. Using protein misfolding cyclic amplification we
demonstrate that scrapie PrPSc can be detected within circulating dusts that are
present on a farm that is naturally contaminated with sheep scrapie. The
presence of infectious scrapie within airborne dusts may represent a possible
route of infection and illustrates the difficulties that may be associated with
the effective decontamination of such scrapie affected premises.
snip...
Discussion
We present biochemical data illustrating the airborne movement of scrapie
containing material within a contaminated farm environment. We were able to
detect scrapie PrPSc within extracts from dusts collected over a 70 day period,
in the absence of any sheep activity. We were also able to detect scrapie PrPSc
within dusts collected within pasture at 30 m but not at 60 m distance away from
the scrapie contaminated buildings, suggesting that the chance of contamination
of pasture by scrapie contaminated dusts decreases with distance from
contaminated farm buildings. PrPSc amplification by sPMCA has been shown to
correlate with infectivity and amplified products have been shown to be
infectious [14,15]. These experiments illustrate the potential for low dose
scrapie infectivity to be present within such samples. We estimate low ng levels
of scrapie positive brain equivalent were deposited per m2 over 70 days, in a
barn previously occupied by sheep affected with scrapie. This movement of dusts
and the accumulation of low levels of scrapie infectivity within this
environment may in part explain previous observations where despite stringent
pen decontamination regimens healthy lambs still became scrapie infected after
apparent exposure from their environment alone [16]. The presence of sPMCA
seeding activity and by inference, infectious prions within dusts, and their
potential for airborne dissemination is highly novel and may have implications
for the spread of scrapie within infected premises. The low level circulation
and accumulation of scrapie prion containing dust material within the farm
environment will likely impede the efficient decontamination of such scrapie
contaminated buildings unless all possible reservoirs of dust are removed.
Scrapie containing dusts could possibly infect animals during feeding and
drinking, and respiratory and conjunctival routes may also be involved. It has
been demonstrated that scrapie can be efficiently transmitted via the nasal
route in sheep [17], as is also the case for CWD in both murine models and in
white tailed deer [18-20].
The sources of dust borne prions are unknown but it seems reasonable to
assume that faecal, urine, skin, parturient material and saliva-derived prions
may contribute to this mobile environmental reservoir of infectivity. This work
highlights a possible transmission route for scrapie within the farm
environment, and this is likely to be paralleled in CWD which shows strong
similarities with scrapie in terms of prion dissemination and disease
transmission. The data indicate that the presence of scrapie prions in dust is
likely to make the control of these diseases a considerable challenge.
Friday, December 14, 2012
DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced
into Great Britain? A Qualitative Risk Assessment October 2012
snip...
In the USA, under the Food and Drug Administration’s BSE Feed Regulation
(21 CFR 589.2000) most material (exceptions include milk, tallow, and gelatin)
from deer and elk is prohibited for use in feed for ruminant animals. With
regards to feed for non-ruminant animals, under FDA law, CWD positive deer may
not be used for any animal feed or feed ingredients. For elk and deer considered
at high risk for CWD, the FDA recommends that these animals do not enter the
animal feed system. However, this recommendation is guidance and not a
requirement by law.
Animals considered at high risk for CWD include:
1) animals from areas declared to be endemic for CWD and/or to be CWD
eradication zones and
2) deer and elk that at some time during the 60-month period prior to
slaughter were in a captive herd that contained a CWD-positive animal.
Therefore, in the USA, materials from cervids other than CWD positive
animals may be used in animal feed and feed ingredients for non-ruminants.
The amount of animal PAP that is of deer and/or elk origin imported from
the USA to GB can not be determined, however, as it is not specified in TRACES.
It may constitute a small percentage of the 8412 kilos of non-fish origin
processed animal proteins that were imported from US into GB in 2011.
Overall, therefore, it is considered there is a __greater than negligible
risk___ that (nonruminant) animal feed and pet food containing deer and/or elk
protein is imported into GB.
There is uncertainty associated with this estimate given the lack of data
on the amount of deer and/or elk protein possibly being imported in these
products.
snip...
36% in 2007 (Almberg et al., 2011). In such areas, population declines of
deer of up to 30 to 50% have been observed (Almberg et al., 2011). In areas of
Colorado, the prevalence can be as high as 30% (EFSA, 2011). The clinical signs
of CWD in affected adults are weight loss and behavioural changes that can span
weeks or months (Williams, 2005). In addition, signs might include excessive
salivation, behavioural alterations including a fixed stare and changes in
interaction with other animals in the herd, and an altered stance (Williams,
2005). These signs are indistinguishable from cervids experimentally infected
with bovine spongiform encephalopathy (BSE). Given this, if CWD was to be
introduced into countries with BSE such as GB, for example, infected deer
populations would need to be tested to differentiate if they were infected with
CWD or BSE to minimise the risk of BSE entering the human food-chain via
affected venison.
snip...
The rate of transmission of CWD has been reported to be as high as 30% and
can approach 100% among captive animals in endemic areas (Safar et al.,
2008).
snip...
In summary, in endemic areas, there is a medium probability that the soil
and surrounding environment is contaminated with CWD prions and in a
bioavailable form. In rural areas where CWD has not been reported and deer are
present, there is a greater than negligible risk the soil is contaminated with
CWD prion.
snip...
In summary, given the volume of tourists, hunters and servicemen moving
between GB and North America, the probability of at least one person travelling
to/from a CWD affected area and, in doing so, contaminating their clothing,
footwear and/or equipment prior to arriving in GB is greater than negligible.
For deer hunters, specifically, the risk is likely to be greater given the
increased contact with deer and their environment. However, there is significant
uncertainty associated with these estimates.
snip...
Therefore, it is considered that farmed and park deer may have a higher
probability of exposure to CWD transferred to the environment than wild deer
given the restricted habitat range and higher frequency of contact with tourists
and returning GB residents.
snip...
P.97: Scrapie transmits to white-tailed deer by the oral route and has a
molecular profile similar to chronic wasting disease and distinct from the
scrapie inoculum
Justin Greenlee1, S Jo Moore1, Jodi Smith1, M Heather West Greenlee2, and
Robert Kunkle1 1National Animal Disease Center; Ames, IA USA; 2Iowa State
University; Ames, IA USA
The purpose of this work was to determine susceptibility of white-tailed
deer (WTD) to the agent of sheep scrapie and to compare the resultant PrPSc to
that of the original inoculum and chronic wasting disease (CWD). We inoculated
WTD by a natural route of exposure (concurrent oral and intranasal (IN); n D 5)
with a US scrapie isolate. All scrapie-inoculated deer had evidence of PrPSc
accumulation. PrPSc was detected in lymphoid tissues at preclinical time points,
and deer necropsied after 28 months post-inoculation had clinical signs,
spongiform encephalopathy, and widespread distribution of PrPSc in neural and
lymphoid tissues. Western blotting (WB) revealed PrPSc with 2 distinct molecular
profiles. WB on cerebral cortex had a profile similar to the original scrapie
inoculum, whereas WB of brainstem, cerebellum, or lymph nodes revealed PrPSc
with a higher profile resembling CWD. Homogenates with the 2 distinct profiles
from WTD with clinical scrapie were further passaged to mice expressing cervid
prion protein and intranasally to sheep and WTD. In cervidized mice, the 2
inocula have distinct incubation times. Sheep inoculated intranasally with WTD
derived scrapie developed disease, but only after inoculation with the inoculum
that had a scrapie-like profile. The WTD study is ongoing, but deer in both
inoculation groups are positive for PrPSc by rectal mucosal biopsy. In summary,
this work demonstrates that WTD are susceptible to the agent of scrapie, 2
distinct molecular profiles of PrPSc are present in the tissues of affected
deer, and inoculum of either profile readily passes to deer.
Saturday, January 31, 2015
European red deer (Cervus elaphus elaphus) are susceptible to Bovine
Spongiform Encephalopathy BSE by Oral Alimentary route
I strenuously once again urge the FDA and its industry constituents, to
make it MANDATORY that all ruminant feed be banned to all ruminants, and this
should include all cervids as soon as possible for the following
reasons...
======
In the USA, under the Food and Drug Administrations BSE Feed Regulation (21
CFR 589.2000) most material (exceptions include milk, tallow, and gelatin) from
deer and elk is prohibited for use in feed for ruminant animals. With regards to
feed for non-ruminant animals, under FDA law, CWD positive deer may not be used
for any animal feed or feed ingredients. For elk and deer considered at high
risk for CWD, the FDA recommends that these animals do not enter the animal feed
system.
***However, this recommendation is guidance and not a requirement by law.
======
31 Jan 2015 at 20:14 GMT
*** Ruminant feed ban for cervids in the United States? ***
31 Jan 2015 at 20:14 GMT
98 | Veterinary Record | January 24, 2015
EDITORIAL
Scrapie: a particularly persistent pathogen
Cristina Acín
Resistant prions in the environment have been the sword of Damocles for
scrapie control and eradication. Attempts to establish which physical and
chemical agents could be applied to inactivate or moderate scrapie infectivity
were initiated in the 1960s and 1970s,with the first study of this type focusing
on the effect of heat treatment in reducing prion infectivity (Hunter and
Millson 1964). Nowadays, most of the chemical procedures that aim to inactivate
the prion protein are based on the method developed by Kimberlin and
collaborators (1983). This procedure consists of treatment with 20,000 parts per
million free chlorine solution, for a minimum of one hour, of all surfaces that
need to be sterilised (in laboratories, lambing pens, slaughterhouses, and so
on). Despite this, veterinarians and farmers may still ask a range of questions,
such as ‘Is there an official procedure published somewhere?’ and ‘Is there an
international organisation which recommends and defines the exact method of
scrapie decontamination that must be applied?’
From a European perspective, it is difficult to find a treatment that could
be applied, especially in relation to the disinfection of surfaces in lambing
pens of affected flocks. A 999/2001 EU regulation on controlling spongiform
encephalopathies (European Parliament and Council 2001) did not specify a
particular decontamination measure to be used when an outbreak of scrapie is
diagnosed. There is only a brief recommendation in Annex VII concerning the
control and eradication of transmissible spongiform encephalopathies (TSE
s).
Chapter B of the regulation explains the measures that must be applied if
new caprine animals are to be introduced to a holding where a scrapie outbreak
has previously been diagnosed. In that case, the statement indicates that
caprine animals can be introduced ‘provided that a cleaning and disinfection of
all animal housing on the premises has been carried out following
destocking’.
Issues around cleaning and disinfection are common in prion prevention
recommendations, but relevant authorities, veterinarians and farmers may have
difficulties in finding the specific protocol which applies. The European Food
and Safety Authority (EFSA ) published a detailed report about the efficacy of
certain biocides, such as sodium hydroxide, sodium hypochlorite, guanidine and
even a formulation of copper or iron metal ions in combination with hydrogen
peroxide, against prions (EFSA 2009). The report was based on scientific
evidence (Fichet and others 2004, Lemmer and others 2004, Gao and others 2006,
Solassol and others 2006) but unfortunately the decontamination measures were
not assessed under outbreak conditions.
The EFSA Panel on Biological Hazards recently published its conclusions on
the scrapie situation in the EU after 10 years of monitoring and control of the
disease in sheep and goats (EFSA 2014), and one of the most interesting findings
was the Icelandic experience regarding the effect of disinfection in scrapie
control. The Icelandic plan consisted of: culling scrapie-affected sheep or the
whole flock in newly diagnosed outbreaks; deep cleaning and disinfection of
stables, sheds, barns and equipment with high pressure washing followed by
cleaning with 500 parts per million of hypochlorite; drying and treatment with
300 ppm of iodophor; and restocking was not permitted for at least two years.
Even when all of these measures were implemented, scrapie recurred on several
farms, indicating that the infectious agent survived for years in the
environment, even as many as 16 years after restocking (Georgsson and others
2006).
In the rest of the countries considered in the EFSA (2014) report,
recommendations for disinfection measures were not specifically defined at the
government level. In the report, the only recommendation that is made for sheep
is repopulation with sheep with scrapie-resistant genotypes. This reduces the
risk of scrapie recurrence but it is difficult to know its effect on the
infection.
Until the EFSA was established (in May 2003), scientific opinions about TSE
s were provided by the Scientific Steering Committee (SSC) of the EC, whose
advice regarding inactivation procedures focused on treating animal waste at
high temperatures (150°C for three hours) and high pressure alkaline hydrolysis
(SSC 2003). At the same time, the TSE Risk Management Subgroup of the Advisory
Committee on Dangerous Pathogens (ACDP) in the UK published guidance on safe
working and the prevention of TSE infection. Annex C of the ACDP report
established that sodium hypochlorite was considered to be effective, but only if
20,000 ppm of available chlorine was present for at least one hour, which has
practical limitations such as the release of chlorine gas, corrosion,
incompatibility with formaldehyde, alcohols and acids, rapid inactivation of its
active chemicals and the stability of dilutions (ACDP 2009).
In an international context, the World Organisation for Animal Health (OIE)
does not recommend a specific disinfection protocol for prion agents in its
Terrestrial Code or Manual. Chapter 4.13 of the Terrestrial Code, General
recommendations on disinfection and disinsection (OIE 2014), focuses on
foot-and-mouth disease virus, mycobacteria and Bacillus anthracis, but not on
prion disinfection. Nevertheless, the last update published by the OIE on bovine
spongiform encephalopathy (OIE 2012) indicates that few effective
decontamination techniques are available to inactivate the agent on surfaces,
and recommends the removal of all organic material and the use of sodium
hydroxide, or a sodium hypochlorite solution containing 2 per cent available
chlorine, for more than one hour at 20ºC.
The World Health Organization outlines guidelines for the control of TSE s,
and also emphasises the importance of mechanically cleaning surfaces before
disinfection with sodium hydroxide or sodium hypochlorite for one hour (WHO
1999).
Finally, the relevant agencies in both Canada and the USA suggest that the
best treatments for surfaces potentially contaminated with prions are sodium
hydroxide or sodium hypochlorite at 20,000 ppm. This is a 2 per cent solution,
while most commercial household bleaches contain 5.25 per cent sodium
hypochlorite. It is therefore recommended to dilute one part 5.25 per cent
bleach with 1.5 parts water (CDC 2009, Canadian Food Inspection Agency
2013).
So what should we do about disinfection against prions? First, it is
suggested that a single protocol be created by international authorities to
homogenise inactivation procedures and enable their application in all
scrapie-affected countries. Sodium hypochlorite with 20,000 ppm of available
chlorine seems to be the procedure used in most countries, as noted in a paper
summarised on p 99 of this issue of Veterinary Record (Hawkins and others 2015).
But are we totally sure of its effectiveness as a preventive measure in a
scrapie outbreak? Would an in-depth study of the recurrence of scrapie disease
be needed?
What we can conclude is that, if we want to fight prion diseases, and
specifically classical scrapie, we must focus on the accuracy of diagnosis,
monitoring and surveillance; appropriate animal identification and control of
movements; and, in the end, have homogeneous and suitable protocols to
decontaminate and disinfect lambing barns, sheds and equipment available to
veterinarians and farmers. Finally, further investigations into the resistance
of prion proteins in the diversity of environmental surfaces are required.
References
snip...
98 | Veterinary Record | January 24, 2015
Persistence of ovine scrapie infectivity in a farm environment following
cleaning and decontamination
Steve A. C. Hawkins, MIBiol, Pathology Department1, Hugh A. Simmons, BVSc
MRCVS, MBA, MA Animal Services Unit1, Kevin C. Gough, BSc, PhD2 and Ben C.
Maddison, BSc, PhD3 + Author Affiliations
1Animal and Plant Health Agency, Woodham Lane, New Haw, Addlestone, Surrey
KT15 3NB, UK 2School of Veterinary Medicine and Science, The University of
Nottingham, Sutton Bonington, Loughborough, Leicestershire LE12 5RD, UK 3ADAS
UK, School of Veterinary Medicine and Science, The University of Nottingham,
Sutton Bonington, Loughborough, Leicestershire LE12 5RD, UK E-mail for
correspondence: ben.maddison@adas.co.uk Abstract Scrapie of sheep/goats and
chronic wasting disease of deer/elk are contagious prion diseases where
environmental reservoirs are directly implicated in the transmission of disease.
In this study, the effectiveness of recommended scrapie farm decontamination
regimens was evaluated by a sheep bioassay using buildings naturally
contaminated with scrapie. Pens within a farm building were treated with either
20,000 parts per million free chorine solution for one hour or were treated with
the same but were followed by painting and full re-galvanisation or replacement
of metalwork within the pen. Scrapie susceptible lambs of the PRNP genotype
VRQ/VRQ were reared within these pens and their scrapie status was monitored by
recto-anal mucosa-associated lymphoid tissue. All animals became infected over
an 18-month period, even in the pen that had been subject to the most stringent
decontamination process. These data suggest that recommended current guidelines
for the decontamination of farm buildings following outbreaks of scrapie do
little to reduce the titre of infectious scrapie material and that environmental
recontamination could also be an issue associated with these premises.
SNIP...
Discussion
Thorough pressure washing of a pen had no effect on the amount of
bioavailable scrapie infectivity (pen B). The routine removal of prions from
surfaces within a laboratory setting is treatment for a minimum of one hour with
20,000 ppm free chlorine, a method originally based on the use of brain
macerates from infected rodents to evaluate the effectiveness of decontamination
(Kimberlin and others 1983). Further studies have also investigated the
effectiveness of hypochlorite disinfection of metal surfaces to simulate the
decontamination of surgical devices within a hospital setting. Such treatments
with hypochlorite solution were able to reduce infectivity by 5.5 logs to lower
than the sensitivity of the bioassay used (Lemmer and others 2004). Analogous
treatment of the pen surfaces did not effectively remove the levels of scrapie
infectivity over that of the control pens, indicating that this method of
decontamination is not effective within a farm setting. This may be due to the
high level of biological matrix that is present upon surfaces within the farm
environment, which may reduce the amount of free chlorine available to
inactivate any infectious prion. Remarkably 1/5 sheep introduced into pen D had
also became scrapie positive within nine months, with all animals in this pen
being RAMALT positive by 18 months of age. Pen D was no further away from the
control pen (pen A) than any of the other pens within this barn. Localised hot
spots of infectivity may be present within scrapie-contaminated environments,
but it is unlikely that pen D area had an amount of scrapie contamination that
was significantly different than the other areas within this building.
Similarly, there were no differences in how the biosecurity of pen D was
maintained, or how this pen was ventilated compared with the other pens. This
observation, perhaps, indicates the slower kinetics of disease uptake within
this pen and is consistent with a more thorough prion removal and
recontamination. These observations may also account for the presence of
inadvertent scrapie cases within other studies, where despite stringent
biosecurity, control animals have become scrapie positive during challenge
studies using barns that also housed scrapie-affected animals (Ryder and others
2009). The bioassay data indicate that the exposure of the sheep to a farm
environment after decontamination efforts thought to be effective in removing
scrapie is sufficient for the animals to become infected with scrapie. The main
exposure routes within this scenario are likely to be via the oral route, during
feeding and drinking, and respiratory and conjunctival routes. It has been
demonstrated that scrapie infectivity can be efficiently transmitted via the
nasal route in sheep (Hamir and others 2008), as is the case for CWD in both
murine models and in white-tailed deer (Denkers and others 2010, 2013).
Recently, it has also been demonstrated that CWD prions presented as dust when
bound to the soil mineral montmorillonite can be infectious via the nasal route
(Nichols and others 2013). When considering pens C and D, the actual source of
the infectious agent in the pens is not known, it is possible that biologically
relevant levels of prion survive on surfaces during the decontamination regimen
(pen C). With the use of galvanising and painting (pen D) covering and sealing
the surface of the pen, it is possible that scrapie material recontaminated the
pens by the movement of infectious prions contained within dusts originating
from other parts of the barn that were not decontaminated or from other areas of
the farm.
Given that scrapie prions are widespread on the surfaces of affected farms
(Maddison and others 2010a), irrespective of the source of the infectious prions
in the pens, this study clearly highlights the difficulties that are faced with
the effective removal of environmentally associated scrapie infectivity. This is
likely to be paralleled in CWD which shows strong similarities to scrapie in
terms of both the dissemination of prions into the environment and the facile
mode of disease transmission. These data further contribute to the understanding
that prion diseases can be highly transmissible between susceptible individuals
not just by direct contact but through highly stable environmental reservoirs
that are refractory to decontamination.
The presence of these environmentally associated prions in farm buildings
make the control of these diseases a considerable challenge, especially in
animal species such as goats where there is lack of genetic resistance to
scrapie and, therefore, no scope to re-stock farms with animals that are
resistant to scrapie.
Scrapie Sheep Goats Transmissible spongiform encephalopathies (TSE)
Accepted October 12, 2014. Published Online First 31 October 2014
Monday, November 3, 2014
Persistence of ovine scrapie infectivity in a farm environment following
cleaning and decontamination
PPo3-22:
Detection of Environmentally Associated PrPSc on a Farm with Endemic
Scrapie
Ben C. Maddison,1 Claire A. Baker,1 Helen C. Rees,1 Linda A. Terry,2 Leigh
Thorne,2 Susan J. Belworthy2 and Kevin C. Gough3 1ADAS-UK LTD; Department of
Biology; University of Leicester; Leicester, UK; 2Veterinary Laboratories
Agency; Surry, KT UK; 3Department of Veterinary Medicine and Science; University
of Nottingham; Sutton Bonington, Loughborough UK
Key words: scrapie, evironmental persistence, sPMCA
Ovine scrapie shows considerable horizontal transmission, yet the routes of
transmission and specifically the role of fomites in transmission remain poorly
defined. Here we present biochemical data demonstrating that on a
scrapie-affected sheep farm, scrapie prion contamination is widespread. It was
anticipated at the outset that if prions contaminate the environment that they
would be there at extremely low levels, as such the most sensitive method
available for the detection of PrPSc, serial Protein Misfolding Cyclic
Amplification (sPMCA), was used in this study. We investigated the distribution
of environmental scrapie prions by applying ovine sPMCA to samples taken from a
range of surfaces that were accessible to animals and could be collected by use
of a wetted foam swab. Prion was amplified by sPMCA from a number of these
environmental swab samples including those taken from metal, plastic and wooden
surfaces, both in the indoor and outdoor environment. At the time of sampling
there had been no sheep contact with these areas for at least 20 days prior to
sampling indicating that prions persist for at least this duration in the
environment. These data implicate inanimate objects as environmental reservoirs
of prion infectivity which are likely to contribute to disease transmission.
Willingham, Erin McNulty, Kelly Anderson, Jeanette Hayes-Klug, Amy Nalls,
and Candace Mathiason Colorado State University; Fort Collins, CO USA
Chronic wasting disease (CWD) is the transmissible spongiform
encephalopathy (TSE), of free-ranging and captive cervids (deer, elk and moose).
The presence of infectious prions in the tissues, bodily fluids and
environments of clinical and preclinical CWD-infected animals is thought to
account for its high transmission efficiency. Recently it has been recognized
that mother to offspring transmission may contribute to the facile transmission
of some TSEs. Although the mechanism behind maternal transmission is not yet
known, the extended asymptomatic TSE carrier phase (lasting years to decades)
suggests that it may have implications in the spread of prions.
Placental trafficking and/or secretion in milk are 2 means by which
maternal prion transmission may occur. In these studies we explore these avenues
during early and late infection using a transgenic mouse model expressing cervid
prion protein. Na€ıve and CWD-infected dams were bred at both timepoints, and
were allowed to bear and raise their offspring. Milk was collected from the dams
for prion analysis, and the offspring were observed for TSE disease progression.
Terminal tissues harvested from both dams and offspring were analyzed for
prions.
We have demonstrated that
(1) CWDinfected TgCerPRP females successfully breed and bear offspring, and
(2) the presence of PrPCWD in reproductive and mammary tissue from
CWD-infected dams.
We are currently analyzing terminal tissue harvested from offspring born to
CWD-infected dams for the detection of PrPCWD and amplification competent
prions. These studies will provide insight into the potential mechanisms and
biological significance associated with mother to offspring transmission of
TSEs.
==============
P.157: Uptake of prions into plants
Christopher Johnson1, Christina Carlson1, Matthew Keating1,2, Nicole
Gibbs1, Haeyoon Chang1, Jamie Wiepz1, and Joel Pedersen1 1USGS National Wildlife
Health Center; Madison, WI USA; 2University of Wisconsin - Madison; Madison, WI
USA
Soil may preserve chronic wasting disease (CWD) and scrapie infectivity in
the environment, making consumption or inhalation of soil particles a plausible
mechanism whereby na€ıve animals can be exposed to prions. Plants are known to
absorb a variety of substances from soil, including whole proteins, yet the
potential for plants to take up abnormal prion protein (PrPTSE) and preserve
prion infectivity is not known. In this study, we assessed PrPTSE uptake into
roots using laser scanning confocal microscopy with fluorescently tagged PrPTSE
and we used serial protein misfolding cyclic amplification (sPMCA) and detect
and quantify PrPTSE levels in plant aerial tissues. Fluorescence was identified
in the root hairs of the model plant Arabidopsis thaliana, as well as the crop
plants alfalfa (Medicago sativa), barley (Hordeum vulgare) and tomato (Solanum
lycopersicum) upon exposure to tagged PrPTSE but not a tagged control
preparation. Using sPMCA, we found evidence of PrPTSE in aerial tissues of A.
thaliana, alfalfa and maize (Zea mays) grown in hydroponic cultures in which
only roots were exposed to PrPTSE. Levels of PrPTSE in plant aerial tissues
ranged from approximately 4 £ 10 ¡10 to 1 £ 10 ¡9 g PrPTSE g ¡1 plant dry weight
or 2 £ 105 to 7 £ 106 intracerebral ID50 units g ¡1 plant dry weight. Both stems
and leaves of A. thaliana grown in culture media containing prions are
infectious when intracerebrally-injected into mice. ***Our results suggest that
prions can be taken up by plants and that contaminated plants may represent a
previously unrecognized risk of human, domestic species and wildlife exposure to
prions.
===========
***Our results suggest that prions can be taken up by plants and that
contaminated plants may represent a previously unrecognized risk of human,
domestic species and wildlife exposure to prions.***
SEE ;
Friday, May 15, 2015
Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions
Report
*** Singeltary reply ; Molecular, Biochemical and Genetic Characteristics
of BSE in Canada Singeltary reply ;
Monday, October 26, 2015
*** FDA PART 589 -- SUBSTANCES PROHIBITED FROM USE IN ANIMAL FOOD OR FEED
VIOLATIONS OFFICIAL ACTION INDICATED OIA UPDATE October 2015
Sunday, October 25, 2015
USAHA Detailed Events Schedule – 119th USAHA Annual Meeting CAPTIVE
LIVESTOCK CWD SCRAPIE TSE PRION
http://chronic-wasting-disease.blogspot.com/2015/10/usaha-detailed-events-schedule-119th.html
Friday, August 14, 2015
*** Susceptibility of cattle to the agent of chronic wasting disease from
elk after intracranial inoculation ***
Saturday, September 12, 2015
In utero transmission and tissue distribution of chronic wasting
disease-associated prions in free-ranging Rocky Mountain elk
>>>Interestingly, five of fifteen sPMCA positive dams showed no
evidence of PrPCWD in either CNS or LRS, sites typically assessed in diagnosing
CWD. Analysis of fetal tissues harvested from the fifteen sPMCA positive dams
revealed PrPCWD in 80% of fetuses (12/15), regardless of gestational stage.
These findings demonstrate that PrPCWD is more abundant in peripheral tissues of
CWD exposed elk than current diagnostic methods suggest, and that transmission
of prions from mother to offspring may contribute to the efficient transmission
of the CWD in naturally exposed cervid populations.<<<
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
Title: Transmission of scrapie prions to primate after an extended silent
incubation period
Authors
item Comoy, Emmanuel - item Mikol, Jacqueline - item Luccantoni-Freire,
Sophie - item Correia, Evelyne - item Lescoutra-Etchegaray, Nathalie - item
Durand, Valérie - item Dehen, Capucine - item Andreoletti, Olivier - item
Casalone, Cristina - item Richt, Juergen item Greenlee, Justin item Baron,
Thierry - item Benestad, Sylvie - item Hills, Bob - item Brown, Paul - item
Deslys, Jean-Philippe -
Submitted to: Scientific Reports Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 28, 2015 Publication Date: June 30, 2015
Citation: Comoy, E.E., Mikol, J., Luccantoni-Freire, S., Correia, E.,
Lescoutra-Etchegaray, N., Durand, V., Dehen, C., Andreoletti, O., Casalone, C.,
Richt, J.A., Greenlee, J.J., Baron, T., Benestad, S., Brown, P., Deslys, J.
2015. Transmission of scrapie prions to primate after an extended silent
incubation period. Scientific Reports. 5:11573.
Interpretive Summary:
The transmissible spongiform encephalopathies (also called prion diseases)
are fatal neurodegenerative diseases that affect animals and humans. The agent
of prion diseases is a misfolded form of the prion protein that is resistant to
breakdown by the host cells. Since all mammals express prion protein on the
surface of various cells such as neurons, all mammals are, in theory, capable of
replicating prion diseases. One example of a prion disease, bovine spongiform
encephalopathy (BSE; also called mad cow disease), has been shown to infect
cattle, sheep, exotic undulates, cats, non-human primates, and humans when the
new host is exposed to feeds or foods contaminated with the disease agent. The
purpose of this study was to test whether non-human primates (cynomologous
macaque) are susceptible to the agent of sheep scrapie. After an incubation
period of approximately 10 years a macaque developed progressive clinical signs
suggestive of neurologic disease. Upon postmortem examination and microscopic
examination of tissues, there was a widespread distribution of lesions
consistent with a transmissible spongiform encephalopathy. This information will
have a scientific impact since it is the first study that demonstrates the
transmission of scrapie to a non-human primate with a close genetic relationship
to humans. This information is especially useful to regulatory officials and
those involved with risk assessment of the potential transmission of animal
prion diseases to humans.
Technical Abstract:
Classical bovine spongiform encephalopathy (c-BSE) is an animal prion
disease that also causes variant Creutzfeldt-Jakob disease in humans. Over the
past decades, c-BSE's zoonotic potential has been the driving force in
establishing extensive protective measures for animal and human health. In
complement to the recent demonstration that humanized mice are susceptible to
scrapie, we report here the first observation of direct transmission of a
natural classical scrapie isolate to a macaque after a 10-year incubation
period. Neuropathologic examination revealed all of the features of a prion
disease: spongiform change, neuronal loss, and accumulation of PrPres throughout
the CNS.
***This observation strengthens the questioning of the harmlessness of
scrapie to humans, at a time when protective measures for human and animal
health are being dismantled and reduced as c-BSE is considered controlled and
being eradicated. Our results underscore the importance of precautionary and
protective measures and the necessity for long-term experimental transmission
studies to assess the zoonotic potential of other animal prion strains.
Saturday, December 12, 2015
CHRONIC WASTING DISEASE CWD TSE PRION REPORT DECEMBER 14, 2015
Tuesday, December 29, 2015
TEXAS MONTHLY CHRONIC WASTING DISEASE CWD JANUARY 2016 DEER BREEDERS STILL
DON'T GET IT $
Chronic Wasting Unease
The emergence of a deadly disease has wildlife officials and deer breeders
eyeing each other suspiciously.
Wednesday, March 18, 2015
*** Chronic Wasting Disease CWD Confirmed Texas Trans Pecos March 18, 2015
***
Wednesday, March 25, 2015
*** Chronic Wasting Disease CWD Cases Confirmed In New Mexico 2013 and 2014
UPDATE 2015 ***
*** Bayesian Modeling of Prion Disease Dynamics in Mule Deer Using
Population Monitoring and Capture-Recapture Data
‘’Mountain lions prey selectively on CWD infected deer [33] and CWD could
result in an abundance of vulnerable prey, thereby enhancing mountain lion
survival and reproduction [20].’’
please see ;
‘’preliminary results suggesting that bobcats (Lynx rufus) may be
susceptible to white-tailed deer (Odocoileus virginianus) chronic wasting
disease agent.’’
Assessing Transmissible Spongiform Encephalopathy Species Barriers with an
In Vitro Prion Protein Conversion Assay
Christopher J. Johnson1, Christina M. Carlson2, Aaron R. Morawski3, Alyson
Manthei4, Neil R. Cashman5
1USGS National Wildlife Health Center, 2Department of Soil Science,
University of Wisconsin–Madison, 3Laboratory of Immunology, National Institute
of Allergy and Infectious Diseases, National Institutes of Health, 4Merial
Veterinary Scholars Program, School of Veterinary Medicine, University of
Wisconsin–Madison, 5Department of Neurology, University of British Columbia
Summary
Measuring the barrier to the interspecies transmission of prion diseases is
challenging and typically involves animal challenges or biochemical assays.
Here, we present an in vitro prion protein conversion assay with the ability to
predict species barriers.
Date Published: 3/10/2015, Issue 97; doi: 10.3791/52522
Keywords: Medicine, Issue 97, Prion, species barrier, conversion,
immunoblotting, transmissible spongiform encephalopathy, interspecies
transmission Cite this Article
Johnson, C. J., Carlson, C. M., Morawski, A. R., Manthei, A., Cashman, N.
R. Assessing Transmissible Spongiform Encephalopathy Species Barriers with an In
Vitro Prion Protein Conversion Assay. J. Vis. Exp. (97), e52522,
doi:10.3791/52522 (2015). Abstract
Studies to understanding interspecies transmission of transmissible
spongiform encephalopathies (TSEs, prion diseases) are challenging in that they
typically rely upon lengthy and costly in vivo animal challenge studies. A
number of in vitro assays have been developed to aid in measuring prion species
barriers, thereby reducing animal use and providing quicker results than animal
bioassays. Here, we present the protocol for a rapid in vitro prion conversion
assay called the conversion efficiency ratio (CER) assay. In this assay cellular
prion protein (PrPC) from an uninfected host brain is denatured at both pH 7.4
and 3.5 to produce two substrates. When the pH 7.4 substrate is incubated with
TSE agent, the amount of PrPC that converts to a proteinase K (PK)-resistant
state is modulated by the original host’s species barrier to the TSE agent. In
contrast, PrPC in the pH 3.5 substrate is misfolded by any TSE agent. By
comparing the amount of PK-resistant prion protein in the two substrates, an
assessment of the host’s species barrier can be made. We show that the CER assay
correctly predicts known prion species barriers of laboratory mice and, as an
example, show some preliminary results suggesting that bobcats (Lynx rufus) may
be susceptible to white-tailed deer (Odocoileus virginianus) chronic wasting
disease agent.
>>> show some preliminary results suggesting that bobcats (Lynx
rufus) may be susceptible to white-tailed deer (Odocoileus virginianus) chronic
wasting disease agent.
AD.63: Susceptibility of domestic cats to chronic wasting disease
Amy V.Nalls,1 Candace Mathiason,1 Davis Seelig,2 Susan Kraft,1 Kevin
Carnes,1 Kelly Anderson,1 Jeanette Hayes-Klug1 and Edward A. Hoover1
1Colorado State University; Fort Collins, CO USA; 2University of Minnesota;
Saint Paul, MN USA
Domestic and nondomestic cats have been shown to be susceptible to feline
spongiform encephalopathy (FSE), almost certainly caused by consumption of
bovine spongiform encephalopathy (BSE)-contaminated meat. Because domestic and
free-ranging nondomestic felids scavenge cervid carcasses, including those in
areas affected by chronic wasting disease (CWD), we evaluated the susceptibility
of the domestic cat (Felis catus) to CWD infection experimentally. Cohorts of 5
cats each were inoculated either intracerebrally (IC) or orally (PO) with
CWD-infected deer brain. At 40 and 42 mo post-inoculation, two IC-inoculated
cats developed signs consistent with prion disease, including a stilted gait,
weight loss, anorexia, polydipsia, patterned motor behaviors, head and tail
tremors, and ataxia, and progressed to terminal disease within 5 mo. Brains from
these two cats were pooled and inoculated into cohorts of cats by IC, PO, and
intraperitoneal and subcutaneous (IP/SC) routes. Upon subpassage, feline-adapted
CWD (FelCWD) was transmitted to all IC-inoculated cats with a decreased
incubation period of 23 to 27 mo. FelCWD was detected in the brains of all the
symptomatic cats by western blotting and immunohistochemistry and abnormalities
were seen in magnetic resonance imaging, including multifocal T2 fluid
attenuated inversion recovery (FLAIR) signal hyper-intensities, ventricular size
increases, prominent sulci, and white matter tract cavitation. Currently, 3 of 4
IP/SQ and 2 of 4 PO inoculared cats have developed abnormal behavior patterns
consistent with the early stage of feline CWD. These results demonstrate that
CWD can be transmitted and adapted to the domestic cat, thus raising the issue
of potential cervid-to- feline transmission in nature.
www.landesbioscience.com
PO-081: Chronic wasting disease in the cat— Similarities to feline
spongiform encephalopathy (FSE)
PO-081: Chronic wasting disease in the cat— Similarities to feline
spongiform encephalopathy (FSE)
Thursday, May 31, 2012
CHRONIC WASTING DISEASE CWD PRION2012 Aerosol, Inhalation transmission,
Scrapie, cats, species barrier, burial, and more
Monday, August 8, 2011
Susceptibility of Domestic Cats to CWD Infection
Sunday, August 25, 2013
Prion2013 Chronic Wasting Disease CWD risk factors, humans, domestic cats,
blood, and mother to offspring transmission
Feline Spongiform Encephalopathy (FSE) FSE was first identified in the UK
in 1990. Most cases have been reported in the UK, where the epidemic has been
consistent with that of the BSE epidemic. Some other countries (e.g. Norway,
Liechtenstein and France) have also reported cases.
Most cases have been reported in domestic cats but there have also been
cases in captive exotic cats (e.g. Cheetah, Lion, Asian leopard cat, Ocelot,
Puma and Tiger). The disease is characterised by progressive nervous signs,
including ataxia, hyper-reactivity and behavioural changes and is fatal.
The chemical and biological properties of the infectious agent are
identical to those of the BSE and vCJD agents. These findings support the
hypothesis that the FSE epidemic resulted from the consumption of food
contaminated with the BSE agent.
The FSE epidemic has declined as a result of tight controls on the disposal
of specified risk material and other animal by-products.
References: Leggett, M.M. et al.(1990) A spongiform encephalopathy in a
cat. Veterinary Record. 127. 586-588
Synge, B.A. et al. (1991) Spongiform encephalopathy in a Scottish cat.
Veterinary Record. 129. 320
Wyatt, J. M. et al. (1991) Naturally occurring scrapie-like spongiform
encephalopathy in five domestic cats. Veterinary Record. 129. 233.
Gruffydd-Jones, T. J.et al.. (1991) Feline spongiform encephalopathy. J.
Small Animal Practice. 33. 471-476.
Pearson, G. R. et al. (1992) Feline spongiform encephalopathy: fibril and
PrP studies. Veterinary Record. 131. 307-310.
Willoughby, K. et al. (1992) Spongiform encephalopathy in a captive puma
(Felis concolor). Veterinary Record. 131. 431-434.
Fraser, H. et al. (1994) Transmission of feline spongiform encephalopathy
to mice. Veterinary Record 134. 449.
Bratberg, B. et al. (1995) Feline spongiform encephalopathy in a cat in
Norway. Veterinary Record 136. 444
Baron, T. et al. (1997) Spongiform encephalopathy in an imported cheetah in
France. Veterinary Record 141. 270-271
Zanusso, G et al. (1998) Simultaneous occurrence of spongiform
encephalopathy in a man and his cat in Italy. Lancet, V352, N9134, OCT 3, Pp
1116-1117.
Ryder, S.J. et al. (2001) Inconsistent detection of PrP in extraneural
tissues of cats with feline spongiform encephalopathy. Veterinary Record 146.
437-441
Kelly, D.F. et al. (2005) Neuropathological findings in cats with
clinically suspect but histologically unconfirmed feline spongiform
encephalopathy. Veterinary Record 156. 472-477.
3 further cheetah cases have occured, plus 1 lion, plus all the primates,
and 20 additional house cats. Nothing has been published on any of these UK
cases either. One supposes the problem here with publishing is that many
unpublished cases were _born_ long after the feed "ban". Caught between a rock
and a hard place: leaky ban or horizontal transmission (or both).
YOU explained that imported crushed heads were extensively used in the
petfood industry...
http://web.archive.org/web/20060303042720/http://www.bseinquiry.gov.uk/files/yb/1989/04/14001001.pdf
In particular I do not believe one can say that the levels of the scrapie
agent in pet food are so low that domestic animals are not exposed...
http://web.archive.org/web/20040301231838/http://www.bseinquiry.gov.uk/files/yb/1989/04/24003001.pdf
http://web.archive.org/web/20060303042732/http://www.bseinquiry.gov.uk/files/yb/1989/04/25001001.pdf
on occassions, materials obtained from slaughterhouses will be derived from
sheep affected with scrapie or cattle that may be incubating BSE for use in
petfood manufacture...
http://web.archive.org/web/20060303042739/http://www.bseinquiry.gov.uk/files/yb/1989/05/03007001.pdf
*** Meldrum's notes on pet foods and materials used
http://web.archive.org/web/20060303042745/http://www.bseinquiry.gov.uk/files/yb/1989/05/16001001.pdf
*** BSE & Pedigree Petfoods ***
http://web.archive.org/web/20060303042725/http://www.bseinquiry.gov.uk/files/yb/1989/05/16002001.pdf
In 2003, Denver Post reporter Theo Stein interviewed scientists about CWD
spreading though deer and elk in Colorado. Dr. Valerius Geist, who paradoxically
has become a darling of anti-wolfers, made this assertion about the significance
of wolves in containing CWD spread via proteins called prions.
“Wolves will certainly bring the disease to a halt,” he said. “They will
remove infected individuals and clean up carcasses that could transmit the
disease.”
Stein added that “Geist and Princeton University biologist Andrew Dobson
theorize that killing off the wolf allowed CWD to take hold in the first
place.”
Wolves aren’t alone. In a 2009 study titled “Mountain lions prey
selectively on prion-infected mule deer,” researchers in Colorado discovered
that “adult mule deer killed by mountain lions were more likely to be
prion-infected than were deer killed more randomly … suggesting that mountain
lions were selecting for infected individuals when they targeted adult
deer.”
NO, NO, NOT NO, BUT HELL KNOW !!!
PLEASE be careful what you ask for.
recently, canine spongiform encephalopathy has been confirmed.
I proved this in 2005, with a letter from MAFF/DEFRA et al confirming my
suspicions of the ‘hound study’ way back. this was covered up. see documents
below.
also, recently, cwd to the domestic cat is a great concern.
even though to date, as far as I am aware of, the cwd study on the mountain
lion has not produced any confirmation yet, we already know that the feline
species is highly succeptible to the TSE prion. domestic cats and the exotic zoo
big cats.
so in my honest opinion, any program that would use wild animals to prey on
other wild animals, as a tool to help curb CWD TSE prion disease, would only
help enhance the spread of disease, and it would only help spread the disease to
other species. ...TSS
Monday, February 14, 2011
THE ROLE OF PREDATION IN DISEASE CONTROL: A COMPARISON OF SELECTIVE AND
NONSELECTIVE REMOVAL ON PRION DISEASE DYNAMICS IN DEER
NO, NO, NOT NO, BUT HELL NO !
Journal of Wildlife Diseases, 47(1), 2011, pp. 78-93 © Wildlife Disease
Association 2011
snip...
Friday, April 17, 2015
Assessing Transmissible Spongiform Encephalopathy Species Barriers with an
In Vitro Prion Protein Conversion Assay
>>> show some preliminary results suggesting that bobcats (Lynx
rufus) may be susceptible to white-tailed deer (Odocoileus virginianus) chronic
wasting disease agent.
O.05: Transmission of prions to primates after extended silent incubation
periods: Implications for BSE and scrapie risk assessment in human populations
Emmanuel Comoy, Jacqueline Mikol, Val erie Durand, Sophie Luccantoni,
Evelyne Correia, Nathalie Lescoutra, Capucine Dehen, and Jean-Philippe Deslys
Atomic Energy Commission; Fontenay-aux-Roses, France
Prion diseases (PD) are the unique neurodegenerative proteinopathies
reputed to be transmissible under field conditions since decades. The
transmission of Bovine Spongiform Encephalopathy (BSE) to humans evidenced that
an animal PD might be zoonotic under appropriate conditions. Contrarily, in the
absence of obvious (epidemiological or experimental) elements supporting a
transmission or genetic predispositions, PD, like the other proteinopathies, are
reputed to occur spontaneously (atpical animal prion strains, sporadic CJD
summing 80% of human prion cases). Non-human primate models provided the first
evidences supporting the transmissibiity of human prion strains and the zoonotic
potential of BSE. Among them, cynomolgus macaques brought major information for
BSE risk assessment for human health (Chen, 2014), according to their
phylogenetic proximity to humans and extended lifetime. We used this model to
assess the zoonotic potential of other animal PD from bovine, ovine and cervid
origins even after very long silent incubation periods. *** We recently observed
the direct transmission of a natural classical scrapie isolate to macaque after
a 10-year silent incubation period,
***with features similar to some reported for human cases of sporadic CJD,
albeit requiring fourfold longe incubation than BSE. Scrapie, as recently evoked
in humanized mice (Cassard, 2014),
***is the third potentially zoonotic PD (with BSE and L-type BSE),
***thus questioning the origin of human sporadic cases.
We will present an updated panorama of our different transmission studies
and discuss the implications of such extended incubation periods on risk
assessment of animal PD for human health.
===============
***thus questioning the origin of human sporadic cases...TSS
===============
==========================================
***our findings suggest that possible transmission risk of H-type BSE to
sheep and human. Bioassay will be required to determine whether the PMCA
products are infectious to these animals.
==========================================
PRION 2015 CONFERENCE FT. COLLINS CWD RISK FACTORS TO HUMANS
*** LATE-BREAKING ABSTRACTS PRION 2015 CONFERENCE ***
O18
Zoonotic Potential of CWD Prions
Liuting Qing1, Ignazio Cali1,2, Jue Yuan1, Shenghai Huang3, Diane Kofskey1,
Pierluigi Gambetti1, Wenquan Zou1, Qingzhong Kong1 1Case Western Reserve
University, Cleveland, Ohio, USA, 2Second University of Naples, Naples, Italy,
3Encore Health Resources, Houston, Texas, USA
*** These results indicate that the CWD prion has the potential to infect
human CNS and peripheral lymphoid tissues and that there might be asymptomatic
human carriers of CWD infection.
==================
***These results indicate that the CWD prion has the potential to infect
human CNS and peripheral lymphoid tissues and that there might be asymptomatic
human carriers of CWD infection.***
==================
P.105: RT-QuIC models trans-species prion transmission
Kristen Davenport, Davin Henderson, Candace Mathiason, and Edward Hoover
Prion Research Center; Colorado State University; Fort Collins, CO USA
Conversely, FSE maintained sufficient BSE characteristics to more
efficiently convert bovine rPrP than feline rPrP. Additionally, human rPrP was
competent for conversion by CWD and fCWD.
***This insinuates that, at the level of protein:protein interactions, the
barrier preventing transmission of CWD to humans is less robust than previously
estimated.
================
***This insinuates that, at the level of protein:protein interactions, the
barrier preventing transmission of CWD to humans is less robust than previously
estimated.***
================
From: Terry S. Singeltary Sr.
Sent: Saturday, November 15, 2014 9:29 PM
To: Terry S. Singeltary Sr.
Subject: THE EPIDEMIOLOGY OF CREUTZFELDT-JAKOB DISEASE R. G. WILL 1984
THE EPIDEMIOLOGY OF CREUTZFELDT-JAKOB DISEASE
R. G. WILL
1984
*** The association between venison eating and risk of CJD shows similar
pattern, with regular venison eating associated with a 9 FOLD INCREASE IN RISK
OF CJD (p = 0.04). (SEE LINK IN REPORT HERE...TSS) PLUS, THE CDC DID NOT PUT
THIS WARNING OUT FOR THE WELL BEING OF THE DEER AND ELK ;
snip...
85%+ of all human tse prion disease is sporadic CJD.
see what the NIH prion Gods say themselves ;
‘’In the Archives of Neurology you quoted (the abstract of which was
attached to your email), we did not say CWD in humans will present like variant
CJD. That assumption would be wrong.’’
‘’Also, we do not claim that "no-one has ever been infected with prion
disease from eating venison." Our conclusion stating that we found no strong
evidence of CWD transmission to humans in the article you quoted or in any other
forum is limited to the patients we investigated.’’
*** These results would seem to suggest that CWD does indeed have zoonotic
potential, at least as judged by the compatibility of CWD prions and their human
PrPC target. Furthermore, extrapolation from this simple in vitro assay suggests
that if zoonotic CWD occurred, it would most likely effect those of the PRNP
codon 129-MM genotype and that the PrPres type would be similar to that found in
the most common subtype of sCJD (MM1).***
*** The potential impact of prion diseases on human health was greatly
magnified by the recognition that interspecies transfer of BSE to humans by beef
ingestion resulted in vCJD. While changes in animal feed constituents and
slaughter practices appear to have curtailed vCJD, there is concern that CWD of
free-ranging deer and elk in the U.S. might also cross the species barrier.
Thus, consuming venison could be a source of human prion disease. Whether BSE
and CWD represent interspecies scrapie transfer or are newly arisen prion
diseases is unknown. Therefore, the possibility of transmission of prion disease
through other food animals cannot be ruled out. There is evidence that vCJD can
be transmitted through blood transfusion. There is likely a pool of unknown size
of asymptomatic individuals infected with vCJD, and there may be asymptomatic
individuals infected with the CWD equivalent. These circumstances represent a
potential threat to blood, blood products, and plasma supplies.
now, let’s see what the authors said about this casual link, personal
communications years ago. see where it is stated NO STRONG evidence. so, does
this mean there IS casual evidence ???? “Our conclusion stating that we found no
strong evidence of CWD transmission to humans”
From: TSS (216-119-163-189.ipset45.wt.net)
Subject: CWD aka MAD DEER/ELK TO HUMANS ???
Date: September 30, 2002 at 7:06 am PST
From: "Belay, Ermias"
To: Cc: "Race, Richard (NIH)" ; ; "Belay, Ermias"
Sent: Monday, September 30, 2002 9:22 AM
Subject: RE: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
Dear Sir/Madam,
In the Archives of Neurology you quoted (the abstract of which was attached
to your email), we did not say CWD in humans will present like variant CJD. That
assumption would be wrong. I encourage you to read the whole article and call me
if you have questions or need more clarification (phone: 404-639-3091). Also, we
do not claim that "no-one has ever been infected with prion disease from eating
venison." Our conclusion stating that we found no strong evidence of CWD
transmission to humans in the article you quoted or in any other forum is
limited to the patients we investigated.
Ermias Belay, M.D. Centers for Disease Control and Prevention
-----Original Message-----
From: Sent: Sunday, September 29, 2002 10:15 AM
To: rr26k@nih.gov; rrace@niaid.nih.gov; ebb8@CDC.GOV
Subject: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
Sunday, November 10, 2002 6:26 PM ......snip........end..............TSS
Thursday, April 03, 2008
A prion disease of cervids: Chronic wasting disease 2008 1: Vet Res. 2008
Apr 3;39(4):41 A prion disease of cervids: Chronic wasting disease Sigurdson CJ.
snip...
*** twenty-seven CJD patients who regularly consumed venison were reported
to the Surveillance Center***,
snip... full text ;
CJD is so rare in people under age 30, one case in a billion (leaving out
medical mishaps), that four cases under 30 is "very high," says Colorado
neurologist Bosque. "Then, if you add these other two from Wisconsin [cases in
the newspaper], six cases of CJD in people associated with venison is very, very
high." Only now, with Mary Riley, there are at least seven, and possibly eight,
with Steve, her dining companion. "It's not critical mass that matters,"
however, Belay says. "One case would do it for me." The chance that two people
who know each other would both contact CJD, like the two Wisconsin sportsmen, is
so unlikely, experts say, it would happen only once in 140 years.
Given the incubation period for TSEs in humans, it may require another
generation to write the final chapter on CWD in Wisconsin. "Does chronic wasting
disease pass into humans? We'll be able to answer that in 2022," says Race.
Meanwhile, the state has become part of an immense experiment.
I urge everyone to watch this video closely...terry
*** you can see video here and interview with Jeff's Mom, and scientist
telling you to test everything and potential risk factors for humans ***
*** These results would seem to suggest that CWD does indeed have zoonotic
potential, at least as judged by the compatibility of CWD prions and their human
PrPC target. Furthermore, extrapolation from this simple in vitro assay suggests
that if zoonotic CWD occurred, it would most likely effect those of the PRNP
codon 129-MM genotype and that the PrPres type would be similar to that found in
the most common subtype of sCJD (MM1).***
Monday, November 16, 2015
*** Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats Terry Singeltary
Sr. Submission ***
Saturday, December 12, 2015
BOVINE SPONGIFORM ENCEPHALOPATHY BSE TSE PRION REPORT DECEMBER 14, 2015
Thursday, December 24, 2015
Infectious disease spread is fueled by international trade
Thursday, December 17, 2015
Annual report of the Scientific Network on BSE-TSE 2015 EFSA-Q-2015-00738
10 December 2015
*** Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats Terry Singeltary
Sr. Submission ***
Thursday, December 17, 2015
Annual report of the Scientific Network on BSE-TSE 2015 EFSA-Q-2015-00738
10 December 2015
Saturday, December 12, 2015
CREUTZFELDT JAKOB DISEASE CJD TSE PRION REPORT DECEMBER 14, 2015
Thursday, December 24, 2015
Revisiting the Heidenhain Variant of Creutzfeldt-Jakob Disease: Evidence
for Prion Type Variability Influencing Clinical Course and Laboratory Findings
Article type: Research Article
Terry S. Singeltary Sr.
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