Predicting the spread-risk potential of chronic wasting disease to sympatric ungulate species
Research Paper
Predicting the spread-risk potential of chronic wasting disease to sympatric ungulate species
Catherine I. CullinghamORCID Icon,Rhiannon M. PeeryORCID Icon,Anh DaoORCID Icon,Debbie I. McKenzie &David W. ColtmanORCID Icon
Pages 56-66 | Received 22 Oct 2019, Accepted 16 Jan 2020, Published online: 03 Feb 2020
Download citation https://doi.org/10.1080/19336896.2020.1720486
ABSTRACT
Wildlife disease incidence is increasing, resulting in negative impacts on the economy, biodiversity, and potentially human health. Chronic wasting disease (CWD) is a fatal, transmissible spongiform encephalopathy of cervids (wild and captive) which continues to spread geographically resulting in exposure to potential new host species. The disease agent (PrPCWD) is a misfolded conformer of the cellular prion protein (PrPC). In Canada, the disease is endemic in Alberta and Saskatchewan, affecting mule and white-tail deer, with lesser impact on elk and moose. As the disease continues to expand, additional wild ungulate species including bison, bighorn sheep, mountain goat, and pronghorn antelope may be exposed. To better understand the species-barrier, we reviewed the current literature on taxa naturally or experimentally exposed to CWD to identify susceptible and resistant species. We created a phylogeny of these taxa using cytochrome B and found that CWD susceptibility followed the species phylogeny. Using this phylogeny we estimated the probability of CWD susceptibility for wild ungulate species. We then compared PrPC amino acid polymorphisms among these species to identify which sites segregated between susceptible and resistant species. We identified sites that were significantly associated with susceptibility, but they were not fully discriminating. Finally, we sequenced Prnp from 578 wild ungulates to further evaluate their potential susceptibility. Together, these data suggest the host-range for CWD will potentially include pronghorn, mountain goat and bighorn sheep, but bison are likely to be more resistant. These findings highlight the need for monitoring potentially susceptible species as CWD continues to expand.
KEYWORDS: Chronic wasting disease, Prnp, wildlife disease, phylogenetics, species transmission barriers
***> but bison are likely to be more resistant.
or, maybe not...see;
***> Transmissible Spongiform Encephalopathies in exotic species
***> Bison 1 1996
Transmissible Spongiform Encephalopathies in exotic species
In exotic species, the last one was in 2007.
SPECIES No. DATES AFFECTED
Ankole cow 2 1991, 95
Bison 1 1996
Cheetah 5 1992 – 98
Eland 6 1989 – 95
Gemsbok 1 1987
Kudu 6 1989 – 92
Asian Leopard Cat1 1 2005
Lion 5 1998 - 2007
Nyala 1 1986
Ocelot 3 1994 – 99
Oryx 2 1989, 92
Puma 3 1992 – 95
Tiger 3 1995 – 99
Data valid to 30 September 2019
Exotic Ungulate Spongiform Encephalopathy (EUE)
EUE is a TSE of exotic zoo ruminants of the family Bovidae. During a period overlapping with BSE epidemic, 6 greater kudu, 6 elands, 2 each of Arabian oryx and ankole cattle, and 1 each of gemsbok, nyala, scimitar-horned oryx and bison were diagnosed with EUE from UK. The affected animals had been fed meat and bone meal (MBM) derived from ruminants. Indeed, mice inoculated with brain homogenates from greater kudu and nyala with EUE and from cattle with BSE developed a TSE with similar profiles of neuropathological lesions and incubation periods. Strain typing studies in these mice also revealed a similarity between the EUE and BSE strains, supporting the hypothesis that EUE is caused by an infection with PrPBSE. The course of EUE and clinical symptoms varies, according to the species, and are distinct from those of BSE and scrapie. All EUE cases died of this disease [17, 61, 62].
THURSDAY, DECEMBER 19, 2019
TSE surveillance statistics exotic species and domestic cats Update December 2019
SATURDAY, DECEMBER 21, 2019
In vitro detection of haematogenous prions in white-tailed deer orally dosed with low concentrations of chronic wasting disease
8.CONSIDERING RECENT SCIENCE THAT CWD TSE PRION WILL TRANSMIT ORALLY TO PIGS AND ALSO SCRAPIE TO PIGS BY ORAL ROUTES, CONSIDERING CWD TRANSMIT EASILY TO CERVID BY ORAL ROUTE, CONSIDERING A NEW TSE PRION OUTBREAK IN A NEW LIVESTOCK SPECIES, THE CAMEL, CONSIDERING THE FACT THE USA THAT THE 1997 BSE feed regulation at 589.2000, which remains in effect but which applies only to feed for cattle and other ruminants, and specifically, the new section 589.2001, WAS AND STILL IS A TOTAL AND COLOSSAL FAILURE, AND PROVEN TO BE SO BY RECENT COMMENTS COMING FROM THE FDA, BUT FIRST, COMMENTS FROM DEFRA;
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.....
***> cattle, pigs, sheep, cwd, tse, prion, oh my!
***> In contrast, cattle are highly susceptible to white-tailed deer CWD and mule deer CWD in experimental conditions but no natural CWD infections in cattle have been reported (Sigurdson, 2008; Hamir et al., 2006).
Sheep and cattle may be exposed to CWD via common grazing areas with affected deer but so far, appear to be poorly susceptible to mule deer CWD (Sigurdson, 2008). In contrast, cattle are highly susceptible to white-tailed deer CWD and mule deer CWD in experimental conditions but no natural CWD infections in cattle have been reported (Sigurdson, 2008; Hamir et al., 2006). It is not known how susceptible humans are to CWD but given that the prion can be present in muscle, it is likely that humans have been exposed to the agent via consumption of venison (Sigurdson, 2008). Initial experimental research suggests that human susceptibility to CWD is low and there may be a robust species barrier for CWD transmission to humans (Sigurdson, 2008), however the risk appetite for a public health threat may still find this level unacceptable.
cwd scrapie pigs oral routes
***> However, at 51 months of incubation or greater, 5 animals were positive by one or more diagnostic methods. Furthermore, positive bioassay results were obtained from all inoculated groups (oral and intracranial; market weight and end of study) suggesting that swine are potential hosts for the agent of scrapie. <***
>*** Although the current U.S. feed ban is based on keeping tissues from TSE infected cattle from contaminating animal feed, swine rations in the U.S. could contain animal derived components including materials from scrapie infected sheep and goats. These results indicating the susceptibility of pigs to sheep scrapie, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health. <***
***> Results: PrPSc was not detected by EIA and IHC in any RPLNs. All tonsils and MLNs were negative by IHC, though the MLN from one pig in the oral <6 5="" 6="" at="" by="" detected="" eia.="" examined="" group="" in="" intracranial="" least="" lymphoid="" month="" months="" of="" one="" pigs="" positive="" prpsc="" quic="" the="" tissues="" was="">6 months group, 5/6 pigs in the oral <6 4="" and="" group="" months="" oral="">6 months group. Overall, the MLN was positive in 14/19 (74%) of samples examined, the RPLN in 8/18 (44%), and the tonsil in 10/25 (40%).
***> Conclusions: This study demonstrates that PrPSc accumulates in lymphoid tissues from pigs challenged intracranially or orally with the CWD agent, and can be detected as early as 4 months after challenge. CWD-infected pigs rarely develop clinical disease and if they do, they do so after a long incubation period. This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease. Furthermore, lymphoid tissues from CWD-infected pigs could present a potential source of CWD infectivity in the animal and human food chains.
***> In summary, our results establish aerosols as a surprisingly efficient modality of prion transmission. This novel pathway of prion transmission is not only conceptually relevant for the field of prion research, but also highlights a hitherto unappreciated risk factor for laboratory personnel and personnel of the meat processing industry. In the light of these findings, it may be appropriate to revise current prion-related biosafety guidelines and health standards in diagnostic and scientific laboratories being potentially confronted with prion infected materials. While we did not investigate whether production of prion aerosols in nature suffices to cause horizontal prion transmission, the finding of prions in biological fluids such as saliva, urine and blood suggests that it may be worth testing this possibility in future studies.
Adriano Aguzzi ''We even showed that a prion AEROSOL will infect 100% of mice within 10 seconds of exposure''
WOW!...tss
Rabbits are not resistant to prion infection
Francesca Chianinia,1, Natalia Fernández-Borgesb,c,1, Enric Vidald , Louise Gibbarda , Belén Pintadoe , Jorge de Castroc , Suzette A. Priolaf , Scott Hamiltona , Samantha L. Eatona , Jeanie Finlaysona , Yvonne Panga , Philip Steelea , Hugh W. Reida , Mark P. Dagleisha , and Joaquín Castillab,c,g,2 a
Moredun Research Institute, Penicuik, Near Edinburgh EH26 0PZ, Scotland, United Kingdom; b CIC bioGUNE, Derio 48160, Bizkaia, Spain; g IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Bizkaia, Spain; c Department of Infectology, Scripps Florida, Jupiter, FL 33458; f Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; d Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain; and e Centro Nacional de Biotecnología (CNB), 28049 Cantoblanco, Madrid, Spain
Edited by Reed B. Wickner, National Institutes of Health, Bethesda, MD, and approved February 16, 2012 (received for review December 6, 2011)
The ability of prions to infect some species and not others is determined by the transmission barrier. This unexplained phenomenon has led to the belief that certain species were not susceptible to transmissible spongiform encephalopathies (TSEs) and therefore represented negligible risk to human health if consumed. Using the protein misfolding cyclic amplification (PMCA) technique, we were able to overcome the species barrier in rabbits, which have been classified as TSE resistant for four decades. Rabbit brain homogenate, either unseeded or seeded in vitro with disease-related prions obtained from different species, was subjected to serial rounds of PMCA. De novo rabbit prions produced in vitro from unseeded material were tested for infectivity in rabbits, with one of three intracerebrally challenged animals succumbing to disease at 766 d and displaying all of the characteristics of a TSE, thereby demonstrating that leporids are not resistant to prion infection. Material from the brain of the clinically affected rabbit containing abnormal prion protein resulted in a 100% attack rate after its inoculation in transgenic mice overexpressing rabbit PrP. Transmissibility to rabbits (>470 d) has been confirmed in 2 of 10 rabbits after intracerebral challenge. Despite rabbits no longer being able to be classified as resistant to TSEs, an outbreak of “mad rabbit disease” is unlikely.
snip...
In summary, after 3 y postchallenge with three different rabbitderived inocula, we have obtained one positive clinical case, one possible preclinical case, two intercurrent deaths, and six animals that have remained healthy. Although the incubation periods do not directly correlate with the degree of susceptibility, these data might indicate that rabbits are poorly susceptible to prion infection. Although the rabbits used in this study were not inbred, they all had identical full-length PrP sequences and, to date, no difference has been detected in the ORF PrP sequence in any other published rabbit PrP sequence placed in GenBank. To further investigate this, two types of second passage experiment were performed; three raPrPTg mice and 10 rabbits were all intracerebrally inoculated using brain homogenate from the clinically affected rabbit. In contrast to 100% of the de novo RaPrPSc-inoculated transgenic mice having succumbed to a standard clinical prion disease and thereby demonstrating a high rate of transmissibility in vivo, two of 10 rabbits developed a TSE (477 and 540 dpi, respectively) to date. A plausible explanation for the evident differences between these two transmission studies would be the high level of rabbit PrPC expression (4- to 6-fold) in the murine model. In addition, it is well known that even if overexpression does not increase susceptibility, it can significantly reduce the incubation time of disease (2). However, the two positive TSE cases in the second rabbit passage, even though 8 rabbits remained clinically normal at 560 dpi, have led us to conclude that rabbits can no longer be considered a prionresistant species. The long incubation times, even after a second passage, might be due to the presence of some unknown, and probably rare, susceptibility factor in rabbits, which may also be present, for example, in equids and canids.
To critically evaluate this risk, several experiments are currently underway to characterize this new prion disease in rabbits and other species to examine its ability to cross the species barrier. In addition, supplementary experiments have been initiated in rabbits and also in transgenic mice that overexpress rabbit PrPC, to evaluate their susceptibilities to other important prion diseases including CWD and BSE. There are several factors that any potential new TSE epidemic would require: (i) the new prion should be efficiently transmitted through the homologous species; (ii) animals should be edible by humans and should be slaughtered at an age at which the disease has developed, thereby increasing the chance that prions have replicated (especially for those prions that require long incubation times); and (iii) the meat and bone meal should be recycled and fed to new members of the same species. In the light of these data and taking into account the previous three factors, it is unlikely there will be an outbreak of “mad rabbit disease,” and consumers of rabbit meat face much less of a risk than consumers of cattle or sheep products.
THURSDAY, AUGUST 08, 2019
Raccoons accumulate PrPSc after intracranial inoculation with the agents of chronic wasting disease (CWD) or transmissible mink encephalopathy (TME) but not atypical scrapie
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.....
***> READ THIS VERY, VERY, CAREFULLY, AUGUST 1997 MAD COW FEED BAN WAS A SHAM, AS I HAVE STATED SINCE 1997! 3 FAILSAFES THE FDA ET AL PREACHED AS IF IT WERE THE GOSPEL, IN TERMS OF MAD COW BSE DISEASE IN USA, AND WHY IT IS/WAS/NOT A PROBLEM FOR THE USA, and those are;
BSE TESTING (failed terribly and proven to be a sham)
BSE SURVEILLANCE (failed terribly and proven to be a sham)
BSE 589.2001 FEED REGULATIONS (another colossal failure, and proven to be a sham)
these are facts folks. trump et al just admitted it with the feed ban.
see;
FDA Reports on VFD Compliance
John Maday
August 30, 2019 09:46 AM VFD-Form 007 (640x427)
Before and after the current Veterinary Feed Directive rules took full effect in January, 2017, the FDA focused primarily on education and outreach. ( John Maday ) Before and after the current Veterinary Feed Directive (VFD) rules took full effect in January, 2017, the FDA focused primarily on education and outreach to help feed mills, veterinarians and producers understand and comply with the requirements. Since then, FDA has gradually increased the number of VFD inspections and initiated enforcement actions when necessary. On August 29, FDA released its first report on inspection and compliance activities. The report, titled “Summary Assessment of Veterinary Feed Directive Compliance Activities Conducted in Fiscal Years 2016 – 2018,” is available online.
SUNDAY, SEPTEMBER 1, 2019
***> FDA Reports on VFD Compliance
TUESDAY, APRIL 18, 2017
*** EXTREME USA FDA PART 589 TSE PRION FEED LOOP HOLE STILL EXIST, AND PRICE OF POKER GOES UP ***
I STRENUOUSLY URGE TEXAS FDA MODIFY THESE FEED BANS ASAP!
TEXAS CWD JUMPS by 20 cases 3 wild, 17 breeders, with a total of 166 positive to date
Terry S. Singeltary Sr.
posted by Terry S. Singeltary Sr. at
1:05 PM
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