White-tailed deer scavenging community in a chronic wasting disease-endemic region and considerations for prion movement

 26 April 2026

White-tailed deer scavenging community in a chronic wasting disease-endemic region and considerations for prion movement

Marcelo H. Jorge, Lisa A. Jorge, Dana Jarosinski, Richard B. Chandler, Gino J. D’Angelo, Mark G. Ruder & Michael J. Chamberlain Scientific Reports , Article number: (2026) Cite this article

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Abstract

Scavengers impact the geographic spread of pathogens through complex interactions that can either decrease or increase the risk of transmission. Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy fatal to cervids and has been detected throughout much of the United States and internationally. Chronic wasting disease prions have long environmental persistence, and some scavengers have been shown to pass infectious CWD prions through their digestive tracts. We designed a study in a CWD-endemic area of northwestern Arkansas, to determine which scavengers routinely fed on white-tailed deer carcasses and therefore have the potential to be involved in movement or sequestration of CWD prions. Using videos from game cameras, we recorded 25 species that visited white-tailed deer carcasses and calculated abundance, presence duration, and feeding rate. American crows had the greatest number of individuals per video (5.33, 95% CI 3.88–7.32), followed by turkey vultures (3.03, 2.21–4.16), and black vultures (2.94, 2.14–4.04). Black vultures had the longest bout duration in minutes (10.46, 8.01–13.67), followed by bald eagles (9.00, 6.88–11.77) and turkey vultures (8.45, 6.47–11.04). Bald eagles (50%, 38–62%), black vultures (49%, 40–58%), and American black bears (45%, 33–56%) spent the greatest proportion of time feeding, respectively. Species rank varied across metrics, but the average of the three measurements indicated that black vultures, bald eagles, and turkey vultures had the greatest potential to ingest and potentially move CWD prions. Our research highlights the need to experimentally evaluate more avian scavengers for the potential to spread infectious prions.

snip…

During such a movement, turkey vultures would have the opportunity to deposit CWD prions in their feces across five states and this would not include any additional scavenging of CWD positive carcasses along the way.

https://www.nature.com/articles/s41598-026-50064-6

Considering past, present, feeding practices, and failures there from, and considering the TSE PrP survives the digestive system, and passes in feces, I would still consider poultry meal a risk factor for TSE PrP, imo…terry

As the crow flies, so can Cwd

“Results revealed that prions remain infectious after traveling through the digestive system of crows and are present in the feces, causing disease in test mice.”

Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species

Justin W Fischer1, Tracy A Nichols1, Gregory E Phillips1, Kurt C VerCauteren1 1Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, USDA

Correspondence to: Kurt C VerCauteren at kurt.c.vercauteren@aphis.usda.gov URL: http://www.jove.com/video/50853

DOI: doi:10.3791/50853

Keywords: Infection, Issue 81, American crows, feces, mouse model, prion detection, PrPRes, scrapie, TSE transmission

Date Published: 11/6/2013

Citation: Fischer, J.W., Nichols, T.A., Phillips, G.E., VerCauteren, K.C. Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species. J. Vis. Exp. (81), e50853, doi:10.3791/50853 (2013).

Abstract

Infectious prion (PrPRes) material is likely the cause of fatal, neurodegenerative transmissible spongiform encephalopathy (TSE) diseases1. Transmission of TSE diseases, such as chronic wasting disease (CWD), is presumed to be from animal to animal2,3 as well as from environmental sources4-6. Scavengers and carnivores have potential to translocate PrPRes material through consumption and excretion of CWD- contaminated carrion. Recent work has documented passage of PrPRes material through the digestive system of American crows (Corvus brachyrhynchos), a common North American scavenger7.

Snip… Avian scavengers, such as crows, vultures, and eagles, could play a role in the spread of TSE diseases, namely CWD in North America. These species could consume CWD-positive tissue from diseased carcasses or entrails (in the case of hunter-killed cervids) and translocate infectious material in their feces to CWD-free areas or populations of cervids. As the practice of feeding grain to cervids, in wild or captive settings, attracts crows which can defecate on the food source and be inadvertently consumed by cervids, is thus a high-risk practice (VerCauteren personal observation). Further, though the odds of CWD-free animals encountering PrPRes material through random feces deposition may be low, areas where crows and thus their feces are concentrated, like below communal roosting sites, could become of high-risk areas for disease transmission since prions are so persistent in the environment30,31.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970700/

SUNDAY, JULY 07, 2013

Could avian scavengers translocate infectious prions to disease-free areas initiating new foci of chronic wasting disease?

Wednesday, October 17, 2012

Prion Remains Infectious after Passage through Digestive System of American Crows (Corvus brachyrhynchos)

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 !

Monday, July 13, 2009

Deer Carcass Decomposition and Potential Scavenger Exposure to Chronic Wasting Disease

SUNDAY, NOVEMBER 01, 2009 SINGELTARY AS THE CROW FLIES American crows (Corvus brachyrhynchos) and potential spreading of CWD through feces of digested infectious carcases Could Crows Play a Role in Spreading CWD

was presented by Dr. Kurt VerCauteren, NWRC, WS-APHIS- USDA. From the first observations (40 years ago) of CWD in mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus nelsoni) in Northern Colorado, the disease has been identified in an increasing geographic area. Mechanisms for the spread of CWD are incompletely understood. Birds have been identified as potential vectors for a number of diseases, where infected material is ingested and the disease agent is later shed in new areas after flying substantial distances. We hypothesized that avian scavengers have the potential to disseminate 200 prions associated with transmissible spongiform encephalopathies (TSEs), like CWD, by a similar process. As prions are resistant to destruction, it is reasonable that infectious material could pass through the digestive tract of scavenging birds. Our objective was to determine if TSE-positive brain material from mice (i.e., mouse-adapted scrapie) could pass through the digestive tract of American crows (Corvus

American crows (Corvus brachyrhynchos) and potential spreading of CWD through feces of digested infectious carcasses

brachyrhynchos) and still be infectious to mice. Our experimental design included treatment groups of mice inoculated intraperitoneally with: 1) normal mouse brain, 2) infected mouse brain, 3) gamma-irradiated feces from crows gavaged with normal mouse brain, and 4) gamma-irradiated feces from crows gavaged with infected mouse brain. Our preliminary results indicate feces from each of 20 crows gavaged with infected mouse brain were infectious for mice (proportion of crows=1.00, 95% CI: 0.83-1.00) and average longevity for mice was 213 days (95% CI: 210-216). Longevity of mice inoculated with infected mouse brain was slightly less (198 days, 95% CI: 188-207). Most mice inoculated with normal brain, or feces from crows gavaged with normal brain, were still alive 1 year post inoculation with no evident clinical signs of TSE disease in any control mice. Our results demonstrate that a common, migratory North American scavenger, the American crow, can pass infective prions in feces and, therefore, could play a role in the spatial dissemination of prion disease....

Chronic wasting disease (CWD), first identified in Wisconsin in 2002, is an infectious transmissible spongiform encephalopathy (TSE) afflicting members of the taxonomic family Cervidae, and causes neurodegeneration and ultimately death. As a proxy for mortality or harvest of CWD-infected deer, we placed disease-free white-tailed deer (Odocoileus virginianus) carcasses and gut piles in the environment and monitored scavenger activity and carcass removal from September to April in 2003 through 2005. We recorded 14 species of scavenging mammals (six species of visitors), and eight species of scavenging birds (14 species of visitors). Prominent scavengers included American crows (Corvus brachyrhynchos), raccoons (Procyon lotor), and Virginia opossums (Didelphis virginiana). We found no evidence that deer directly consumed conspecific remains, but they visited carcasses and gut piles. Domestic dogs (Canis familiaris), cats (Felis sylvestris catus), and cows (Bos spp.) either scavenged or visited carcass sites, which may have increased exposure risk of CWD to humans and human food supplies. Deer carcasses persisted for a median of 18 to 101 days, while gut piles lasted for a median of three days. Habitat did not influence carcass consumption/decomposition, but mammalian and avian scavenger activity and higher temperatures (proxy for microbial and arthropod activity) were associated with greater rates of carcass removal. Our findings suggest that infected deer carcasses can function as an environmental source of CWD prions to mammalian and avian scavengers. We discuss the implications of these results in a broader context of CWD spread, and suggest preemptive management strategies for mitigating impacts of CWD contaminated deer remains in the environment....

http://www.usaha.org/meetings/2008/2008_USAHA_Proceedings.pdf

archive url;

https://web.archive.org/web/20100202225356/http://www.usaha.org/meetings/2008/2008_USAHA_Proceedings.pdf

1999 “I believe it was Dr. Joe Gibbs, that said, the prion protein, can survive the digestinal track. So you have stopped nothing.”

Greetings,

THIS potential vector of transmission is very disturbing. I don't know what the flight paths, and or travel of either species of birds, or if there are others, there are many birds that eat meat and or are scavengers. But the disturbing part is the amount of territory they can cover and spread their feces. PLUS, this goes back to what the late Dr. Gibbs told me, and what the late Harash Narang book showed, Dr. Gibbs stating that the TSE agent could spread through the digestinal track, and survive, and could still have the potential to spread, and Harash Narang's book 'The Link', page 135, where a farmers around Kent have chickens with BSE. MAFF was aware of this and was suppose to do some studies? BUT, regardless whether or not these birds become clinical and die, the fact that the above studies showed that the TSE agent survived the digestinal tract, and went on to further infect mice via feces, is very disturbing, and further enhances transmission studies must be done asap. PLUS, this should be the final straw for chicken litter being fed back to cattle and other food producing animals for humans and animals. AND not to forget the Red Necked Ostrich and BSE? ...TSS “I believe it was Dr. Joe Gibbs, that said, the prion protein, can survive the digestinal track” Re: vCJD in the USA * BSE in U.S. 15 November 1999 Terry S Singeltary, NA medically retired Send response to journal: Re: Re: vCJD in the USA * BSE in U.S. Our feeding and rendering practices have mirrored that of the U.K. for years, some say it was worse. Everything from the downer cattle, to those scrapie infected sheep, to any roadkill, including the city police horse and the circus elephant went to the renders for feed and other products for consumption. Then they only implemented a partial feed ban on Aug. 4, 1997, but pigs, chickens, dogs, and cats, and humans were exempt from that ban. So they can still feed pigs and chickens those potentially TSE tainted by-products, and then they can still feed those by-products back to the cows. I believe it was Dr. Joe Gibbs, that said, the prion protein, can survive the digestinal track. So you have stopped nothing. It was proven in Oprah Winfrey's trial, that Cactus Cattle feeders, sent neurologically ill cattle, some with encephalopathy stamped on the dead slips, were picked up and sent to the renders, along with sheep carcasses. Speaking of autopsies, I have a stack of them, from CJD victims. You would be surprised of the number of them, who ate cow brains, elk brains, deer brains, or hog brains. Terry S. Singeltary Sr., Bacliff, Texas 77518 USA flounder@wt.net

http://www.bmj.com/cgi/eletters/319/7220/1312/b

https://web.archive.org/web/20100627090516/http://www.bmj.com/cgi/eletters/319/7220/1312/b

http://www.bmj.com/cgi/eletters/320/7226/8/b#EL1

SE1806

TRANSMISSION STUDIES OF BSE TO DOMESTIC FOWL BY ORAL EXPOSURE TO BRAIN HOMOGENATE

1 challenged cock bird was necropsied (41 months p.i.) following a period of ataxia, tremor, limb abduction and other neurological signs. Histopathological examination failed to reveal any significant lesions of the central or peripheral nervous systems...

snip...

94/01.19/7.1

https://web.archive.org/web/20090506013034/http://www.bseinquiry.gov.uk/files/yb/1994/01/19007001.pdf

https://web.archive.org/web/20090506013034/http://www.bseinquiry.gov.uk/files/yb/1994/01/19007001.pdf

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even the late great Dr. Gibbs once told me personally that even if the Chicken did not contract a TSE, IF the chicken had been fed the TSE tainted feed and then slaughtered, the agent survives the digestinal tract to pass on to other species through feed...

TSS

Date: Tue, 27 May 2003 08:07:58 -0500

Reply-To: Bovine Spongiform Encephalopathy

Sender: Bovine Spongiform Encephalopathy

From: "Terry S. Singeltary Sr." Subject: FDA BSE Update - Pet Food from Canadian Manufacturer & MAD DOG DATA

######## Bovine Spongiform Encephalopathy #########

snip...see;

A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY

https://web.archive.org/web/20090505211737/http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf

https://web.archive.org/web/20090505211737/http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf

OPINION on : NECROPHAGOUS BIRDS AS POSSIBLE TRANSMITTERS OF TSE/BSE ADOPTED BY THE SCIENTIFIC STEERING COMMITTEE AT ITS MEETING OF 7-8 NOVEMBER 2002

OPINION

1. Necrophagous birds as possible transmitters of BSE. The SSC considers that the evaluation of necrophagous birds as possible transmitters of BSE, should theoretically be approached from a broader perspective of mammals and birds which prey on, or are carrion eaters (scavengers) of mammalian species. Thus, carnivorous and omnivorous mammals, birds of prey (vultures, falcons, eagles, hawks etc.), carrion eating birds (crows, magpies etc.) in general could be considered possible vectors of transmission and/or spread of TSE infectivity in the environment. In view also of the occurrence of Chronic Wasting Disease (CWD) in various deer species it should not be accepted that domestic cattle and sheep are necessarily the only source of TSE agent exposure for carnivorous species. While some information is available on the susceptibility of wild/exotic/zoo animals to natural or experimental infection with certain TSE agents, nothing is known of the possibility of occurrence of TSE in wild animal populations, other than among the species of deer affected by CWD in the USA.

1 The carrion birds are animals whose diet regularly or occasionally includes the consumption of carcasses, including possibly TSE infected ruminant carcasses.

http://ec.europa.eu/food/fs/sc/ssc/out295_en.pdf

EUROPEAN COMMISSION HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL

Scientific Steering Committee

OPINION on :

NECROPHAGOUS BIRDS AS POSSIBLE TRANSMITTERS OF TSE/BSE

ADOPTED BY

THE SCIENTIFIC STEERING COMMITTEE

EUROPEAN COMMISSION

HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL

NECROPHAGOUS BIRDS AS POSSIBLE TRANSMITTERS OF

TEERING

OMMITTEE

7-8 N

OVEMBER

2002

OPINION

BACKGROUND AND MANDATE

Concern has been raised to the theoretical risk that carrion1 or necrophagous birds could play arole in the spread of TSE and exposure to TSE of humans by contracting the disease, byspreading the agent passively in waste from their food or by exposure of persons involved inhandling the birds and the direct release of the agent in the environment. On 9 October 2001the CMIEET (Multidisciplinary Scientific Committee for Research into TransmissibleSpongiform Encephalopathies, Spain), adopted a scientific opinion and report on Carrion birdsas possible vectors of bovine spongiform encephalopathy and on possible alternatives to the useof ruminant carcasses as food for these animals. The Scientific Steering Committee wassubsequently requested to:

(1)Evaluate the opinion of the Spanish Scientific Committee on TSEs in relation tonecrophagous birds being possible transmitters of BSE and

(2) Advise on the safety with regard to TSE risks for the use of dead ruminants containingspecified risk material (SRM) for the feeding of necrophagous birds and, if appropriate,suggest examples of conditions under which such feeding can be carried out safely.

The opinion hereafter pays special attention to the above mentioned spanish report and is basedon the discussions held by the TSE/BSE ad hoc Group at its meetings of 25 July and 5September 2002 (rapporetur: Dr.E.Vanopdenbosch), as well as contributions fromProf.Dr.L.Bolis, Dr.P.Brown and Dr.R.Bradley.

OPINION

1.Necrophagous birds as possible transmitters of BSE.

The SSC considers that the evaluation of necrophagous birds as possible transmitters ofBSE, should theoretically be approached from a broader perspective of mammals andbirds which prey on, or are carrion eaters (scavengers) of mammalian species. Thus,carnivorous and omnivorous mammals, birds of prey (vultures, falcons, eagles, hawksetc.), carrion eating birds (crows, magpies etc.) in general could be considered possiblevectors of transmission and/or spread of TSE infectivity in the environment. In view alsoof the occurrence of Chronic Wasting Disease (CWD) in various deer species it should notbe accepted that domestic cattle and sheep are necessarily the only source of TSE agentexposure for carnivorous species. While some information is available on the susceptibilityof wild/exotic/zoo animals to natural or experimental infection with certain TSE agents,nothing is known of the possibility of occurrence of TSE in wild animal populations, otherthan among the species of deer affected by CWD in the USA.

The SSC therefore took, in addition to the opinion of the Spanish CMIEET, also thefollowing publications into account2:

-SSC Opinion (1999) on the risks of non conventional transmissible agents,conventional infectious agents or other hazards such as toxic substances entering thehuman food or animal feed chains via raw material from fallen stock and dead animals(including also: ruminants, pigs, poultry, fish, wild/exotic/zoo animals, fur animals,cats, laboratory animals and fish) or via condemned materials.

- SSC Opinion (1999) on the risk born by recycling animal by-products as feed withregard to propagating TSE in non-ruminant farmed animals.

-SSC Opinion (2000) on the Scientific basis for import bans proposed by 3 memberstates with regard to BSE risks in France and the Republic of Ireland; on the Scientificbasis for several measures proposed by France with regard to BSE risks and on theScientific basis for banning animal protein from feed for all farmed animals, includingpig, poultry, fish and pet animals.

-Scrimgeour, E. M., et al., 1996. Disposal of rendered offal. The Veterinary Record,August 31, 219-220. This paper raises the issue of birds as uninfected vectors ofinfectivity from landfill carcass sites in 1996.

-Tella, J.L., 2001. Action is needed now, or BSE crisis could wipe out endangeredbirds of prey. Nature, 410: 408.

The SSC analysed the above literature from the following perspectives:

-The risk of TSE infection and agent replication in birds in general and in necrophagousbirds in particular;

-Risk of passive spread of TSE

-Human exposure risk

It concluded as follows:

-The scientific basis (both literature and field data) for advising on the safety withregard to TSE risks, of the use of dead ruminants containing specified risk material(SRM) as bird feed, is very limited. As far as birds are concerned, most data relate tothe domestic fowl. No literature could be found on aspects such as microscopic brainexaminations in zoo carnivorous/omnivorous birds (often fed on waste bovine materialthat in the past may have been infected with BSE) nor on the epidemiology of TSEs aspossibly influenced by the role of prey animals and carrion eaters (scavengers)3.

-The possibility of active replication of PrPSc in birds is remote, if existing at all.(Necrophagous and omnivorous) birds are nevertheless able to ingest BSE infectiousmaterial and to spread the ingested infectious material through dissemination of faecesbecause it is unlikely that the pathological prion protein would be completelydestroyed in the digestive tract. Moreover, plumage, claws and beak may also becontaminated with infectious material, which is then released into the environment.

-Although there is no data on TSE epidemiology indicating any significant role of anysuch pathways in the spread of scrapie, it cannot be excluded that they could play apart in the transportation of TSE infected materials, given that these birds can covergreat distances and may also migrate.

2 safety with regard to TSE risks of the use of dead ruminants containing specified riskmaterial (SRM) for the feeding of necrophagous birds; examples of conditions underwhich such feeding can be carried out safely.

One could theoretically consider implementing rigorous health measures to prevent birdsfrom having access to carcasses of animal species susceptible to TSE, but in view of thevery limited human exposure risk this may bring about changes to the ecology created bythe traditional practices and could jeopardise the conservation of certain animal species.On the other hand, feeding practices should not lead to an artificial increase of the numberof potential TSE transmission sources, and their possible spread. Whereas it is recognisedthat the removal of fallen animals from remote wild areas is not a realistic option under allcircumstances, the SSC considers that feeding programmes of wild species such asnecrophagous birds should thus not become an alternative way of disposal of fallenruminant stock posing a TSE risk nor of specified risk materials.

The SSC considers that the above recommendations are for the time being also valid forother prey animals and carrion eaters (scavengers), for which even less literature isavailable.

3.The above conclusions are consistent with the opinion of 9 October 2001 of the CMIEET and withits main conclusions.

Annex:

CMIEET Multidisciplinary Scientific Committee for Research intoTransmissible Spongiform Encephalopathies

Ministry of Science and Technology

SCIENTIFIC OPINION:

REPORT ON CARRION BIRDS AS POSSIBLE VECTORS OF BOVINE SPONGIFORMENCEPHALOPATHY

(POSSIBLE ALTERNATIVES TO THE USE OF RUMINANT CARCASSES AS FOODFOR THESE ANIMALS)

Adopted by CMIEET during its meeting held in Madrid on 9 October 2001

-----------------------

Translation into English of:

OPINIÓN CIENTÍFICA:

INFORME SOBRE LAS AVES CARROÑERAS COMO POSIBLES VECTORES DE LAENCEFALOPATÍA ESPONGIFORME BOVINA

(POSIBLES ALTERNATIVAS AL USO DE CADÁVERES DE RUMIANTES PARA ELABASTECIMIENTO DE ESTOS ANIMALES)

Adoptada por el Comité Científico Multidisciplinar para la Investigación enEncefalopatías Espongiformes Transmisibles (CMIEET), Ministerio de Ciencia yTecnología, en su reunión celebrada en Madrid, el 9 de Octubre de 2001

Note:

When producing this report CMIEET concentrated on analysing and discussinginformation published in scientific reviews. Other technical documents, such ascompilations of existing legislation and documents provided by organisations andpersons involved in natural resources management, were also taken into consideration.

Please note that opinions expressed by CMIEET are not necessarily binding on theMinistry of Science and Technology.

INDEX

Page Executive Summary 3 Subject matter 4 Definitions and Abbreviations 4 Background 4 Analysis of Scientific Evidence and Discussion

V.1. Information on TSEs in necrophagous birds

V.2. Information on TSEs in birds in general

V.3. Digestive physiology of necrophagous birds with possible effectson the viability of the agent

V.4. Evaluation of uncertainties surrounding the possibility ofnecrophagous birds becoming infected by or spreading the BSE agent

V.5. Practical proposals for action regarding the use of carcassesfrom other species to feed these birds

V.6. The potential role of other wild species in the spread of TSEs 5

Conclusions

13 References 14 Annexes

VIII.1. Annex I. Carrion bird numbers

VIII.2. Annex II. Specific information required

EXECUTIVE SUMMARY

The eradication of TSEs will require the removal of potential sources of the agent, such asbovine (and ovine) carcasses, from the natural environment. This will result in the elimination, orat least the reduction, of food sources for necrophagous species, for the conservation of whichSpain has responsibilities unique in Europe.

There are no studies on the presence of TSE in necrophagous birds, nor is there any solidevidence that such processes affect birds in general. In fact, it has not even been possible todemonstrate birds’ sensitivity to BSE under test conditions. This absence of observations cantheoretically be explained by the low level of similarity — only 30% — between prion proteinsequences of birds and mammals.

The possibility of necrophagous birds’ digestive systems being somehow adapted to breakingdown and extracting nutrients from prion proteins could be of great importance, not only in theinterests of ensuring environmental biosafety but also as a potential final stage in the eliminationof TSE risks: there is therefore a case for research into this issue.

There are two alternatives to deal with the immediate problem of food for necrophagous birds: a)keep using bovine carcasses, but on the condition that rapid test results are negative b) replacingthem by other species not susceptible to BSE. The first alternative will not result in anysubstantial increase in costs since tests on all dead bovines have been obligatory since 1 July2001 (Order of 26 July 2001). The second could create complex logistical problems and beconsiderably more expensive in regions where numbers of such species are low.

Consideration should be given to a moratorium on the use of sheep carcasses until it can bedemonstrated that any cases of scrapie emerging in this country are unrelated to processes causedby the BSE agent.

If we take the global view of the issue of prions in the environment, we should also pay specialattention to the possible problems related to other wild species documented as being susceptibleto TSEs, such as mustelids (occasional carrion eaters) and cervids. We must also not lose sight ofthe potential for disaster if the Iberian lynx, a unique and endangered species, were to becomeinvolved in a possible wild BSE cycle.

We must also draw attention to the need for detailed studies of costs and of the uncertaintiessurrounding the numbers of domestic species and carrion animals, and for research into theirsusceptibility to TSEs and into the role which other wild species may play in the survival andspread of TSEs in the natural environment.

SUBJECT MATTER

Carrion birds as possible vectors of bovine spongiform encephalopathy. Possible alternatives tothe use of ruminant carcasses as food for such animals

DEFINITIONS AND ABBREVIATIONS

Carrion or necrophagous animals: Carnivorous or omnivorous animals whose diet regularly oroccasionally includes the consumption of carcasses. Annex I contains a list of the specificcarrion birds referred to in this report.

AC: Autonomous Community

TSE: Transmissible spongiform encephalopathy

BSE: bovine spongiform encephalopathy

SRM: specific risk materials

PrP: Prion protein

PrPC: normal prion cellular protein

PrPSC: Resistant or pathological prion protein associated with scrapie and considered to beresponsible for transmissible spongiform encephalopathies

SEO: Sociedad Española de Ornitología (Spanish Ornithological Society)

CNS: Central Nervous System

BACKGROUND

The European programme for the eradication of transmissible spongiform encephalopathies inanimals requires all sources of contagion to be monitored and destroyed. This implies thatcarcasses of animals which may potentially have been infected should be removed from theenvironment and destroyed under the correct conditions. This measure, which is of primaryimportance for TSE control, has an unwanted side effect – namely, the disappearance oftraditional sources of food for necrophagous species. This group includes mammals and birds,although the latter have received more public attention because of their higher visibility andbecause some of them are endemic species in danger of extinction (Directives 79/409/EEC and91/244/EEC, Law 4/1989). In this connection we must point out that Spain is the main reservefor carrion birds in Europe since it is home to more than 80-90% of the populations of these birds(Annex I), plus one unique species, the lammergeier or bearded vulture. Implementing rigoroushealth measures to remove animal carcasses would bring about changes to the traditional semi-natural equilibrium and could jeopardise the conservation of an irreplaceable part of our naturalheritage.

In this context of biological conservation, we must draw attention to the potential problem ofcirculation of TSE agents in wild species since some of these species, such as mustelids andcervids, have proven susceptible to TSE. As far as the former are concerned, we must stress thateven though these animals rarely feed on carrion they cannot be discounted as possible carriersof TSEs given our lack of knowledge of TSE epidemiology. It should also be borne in mind thatthere are other land species apart from carrion birds which feed on animal carcasses and whoserole has gone ignored until now. These species, some of which are of immense biological value,could also be affected if this food source were to disappear. Finally, although cervids may notappear to present an immediate problem they should be taken into consideration as part of acomplete analysis of the issue of TSEs in the natural environment.

ANALYSIS OF SCIENTIFIC EVIDENCE AND DISCUSSION

V.1. Information on TSE in necrophagous birds

There is no information of any kind on the presence of TSE in necrophagous birds. This situationdoes not necessarily mean that they are not affected, since, first, it would be difficult to observeinfected birds and, second, no post-mortem studies have been carried out to date. We must notforget that these types of birds are not present in Great Britain, which has seen the highestnumber of cases, and that so far the Spanish situation cannot be considered very serious. Evenso, and if such birds were susceptible to the scrapie agent, one would expect to see over time ahigher mortality rate related to the consumption of sheep, which has not so far been recorded.Thus, if the source of BSE were an ovine strain or a pre-existent and very rare process, we couldeven accept that these species might be resistant to such processes, or at least that they would notplay a major role in their spread, since they certainly could have been exposed to these agents atany time.

[Note: At its meetings of 25 July and 5 September 2002, The TSS/BSE ad hoc Group noticed that there isno scientific information available on the presence of TSE in necrophagous birds, and agrees thatthis absence of evidence does not necessarily mean that they cannot be affected. The Groupfurther considered While vultures do not occur in several other Community countries, carrioneaters do, and so if a wider consideration is to given to the possibility of such species providingtransport of TSE agents, even as mechanical vectors, a broader perspective of the issue isrequired.]

V.2. Information on TSE in birds in general

Various bibliographical searches have only discovered two works describing suspected clinicalsymptoms, where a confirming diagnosis was not obtained, and one experimental attempt atinfection, where transmission was not demonstrated.

In 1991, Schoon et al. described three cases where symptoms compatible with spongiformencephalopathies were observed in ostriches in two zoos in northern Germany, in 1986, 1988 and1989. The birds displayed symptoms of a nervous disorder with ataxia, changes to balance,uncoordinated movements during feeding and microscopic lesions on the brain stem and medullaoblongata similar to those observed in cases of TSE described in mammals. One notable aspect isthat the birds’ feed included meat from livestock animals which had been the subject ofemergency slaughter. However, no conclusive diagnosis could be made since it was not possibleto rule out toxic or nutritional aetiology. The authors referred to the existence of other animals, inboth zoos, which died displaying the same symptoms but could not be examined post-mortem.

In 1996, on a farm in Kent (UK) with cases of BSE in its livestock, a 30-month old hen (allowedthe free run of the farm) displayed symptoms of behavioural change: the animal had troubleentering the coop and became panicked and lost its balance in stressful situations. The processlasted at least 10 weeks and during the final phase it displayed noticeable weight loss,progressive ataxia and violent trembling of the body and limbs. The histological lesions observedcorrespond to neuronal death, more obvious in the Purkinje cells, and minimal vacuolation.Consequent immunohistochemical studies did not shed any light on the aetiology of this process,due to the differences of opinion between the teams which had studied the case (Cawthorne,1997; Narang, 1997).

Dawson et al. in 1991 carried out an experiment on domestic birds, hamsters, pigs and cows,which were intravenously administered with a homogenised preparation of BSE-infected braintissue. The preparation was also administered, orally, to the pigs and birds. Results confirmedthat the disease spread to the cattle and pigs. It was not demonstrated that it had spread tohamsters and birds although tests on these species had not been completed when the results werepublished. No further references from these authors clarifying these data have been found.

[Note: On the basis of the above and of previous opinions of the SSC, the TSE/BSE ad hoc Groupconcluded at its meetings of 25 July and 5 September 2002 that there is no evidence from theworld literature that a natural TSE exists in poultry. Unpublished, but completed experimentalstudies, of the transmissibility of the BSE agent to the domestic fowl have not detected evidenceof transmission. These studies included primary parenteral and oral exposures of domestic fowlchicks to BSE affected brain tissue and subpassage of nervous systems tissue (into furtherchicks, intracerebrally and into a panel of inbred mice) from selected survivors of both primaryexposure experiments (G. A. H. Wells, personal communication). . The possibility that poultry,under field conditions, could after oral exposure,act as healthy carriers in the spread of TSE-agents is l hypothetical and no results of experiments conducted as yet are available to supportthis hypothesis.]

V.3. Digestive physiology of necrophagous birds with possible effects on the viability of theagent

The fact that necrophagous birds are now able to ingest highly infectious materials suggests thatthey may over time have developed resistance to many infectious agents (Houston and Cooper,1975) and may even be able to extract nutrients from them. TSEs documented over the past 200years could be included in this adaptation. Although the capacity for individual immune responsemay be an important mechanism for the species as a whole, a highly efficient digestivephysiology which destroyed pathogenic agents would be much more significant in the interestsof the environment, since this would prevent the passive spread of these agents to sensitivespecies.

The digestive system of carrion birds presents conditions of extreme acidity, around pH 1-1.2 inthe stomach (Houston and Cooper, 1975; Farner, 1967), capable of dissolving bone calciumcompletely. Faecal matter, moreover, is mixed in the cloaca with products consisting almostexclusively of uric acid excreted by the kidneys. While these conditions ensure a high level ofsterilisation in respect of the vast majority of biological pathogenic agents, their effect on prionshas not been fully confirmed, since prion proteins are more sensitive to alkalinity (pH > 10quickly deactivates them) than to acidity. It is for this exact reason — this possibility ofdeactivation by alkalis such as NaOH or sodium hypochlorite — that the effects of acid pH donot appear to have been investigated. The bibliographical research carried out for this reportfound only references to slight deactivation of the scrapie prion at pH 2-10 (Mould et al., 1965)and even at pH 0.1 for one hour in hydrochloric acid (Brown et al., 1986). However, theseobservations contradict the widely recommended practice when handling of material forhistology, namely that it should be deactivated using formic acid (Brown et al., 1990, Taylor,1995, Taylor et al., 1997). This last point suggests that levels of deactivation in acid media mayvary depending on other factors. In this connection, one could extrapolate that conditions in thedigestive tract of carrion birds probably provide these helpful factors both as a means to extractnutritious proteins and as a form of protection against biological agents.

As far as proteolytic enzymes of the digestive system such as trypsin and pepsin are concerned,these do not appear to be capable of effectively destroying prions under test conditions (Taylor,2000), although it cannot be ruled out that under the specific conditions of a combination ofproteolytic factors in carrion birds’ digestive system their activity could be completely efficient.

No specific information has been found concerning these points, so any studies on this subjectshould be considered as being of great interest. If the existence of such a mechanism with aneffect on pathological prion proteins were to be confirmed it would be of great relevance as itwould offer a complementary ecological and low-cost alternative for the destruction of SRM.

V.4. Evaluation of uncertainties surrounding the possibility of necrophagous birdsbecoming infected by or spreading the BSE agent

As far as carrion birds are concerned there are principally three types of risks associated withTSE: a) the risk that they contract the disease, b) the risk of spreading the agent passively inwaste from their food, and c) exposure of persons involved in handling carrion and the directrelease of the agent into the natural environment.

a) Contracting the disease

If these birds were to contract the disease, the agent would be much more widely spread since themajority of these birds are migratory. According to studies carried out in the Iberian Peninsula,approximately 50% of young griffon vultures migrate to Africa, some to settle and some toreturn. Kites and Egyptian vultures are also migratory species, spending winter (80% of theEuropean population of red kites) and summer respectively in Spain.

The existence of a prion protein in birds has been demonstrated, although research has shownthat it has a very low level of similarity — around 30% — to that found in mammals (Gabriel etal., 1992; Wopfner et al., 1999). However new research is necessary since the limited number ofbirds tested did not allow categorical conclusions to be reached (Wopfner et al., 1999).

Moreover, other aspects must be taken into consideration. Studies of different species ofmammals show that, for example, PrP in pigs is very similar to PrP in cattle: the potential forinfection is therefore very high. But while pigs are easily infected by intercerebral contact theyare not infected orally, which clearly suggests that other factors contribute to the development ofPrPSC in an animal (Wopfner et al., 1999).

The potential for transmission can therefore be considered as relatively low, and given theknowledge of the epidemiology of these diseases, would not require special measures to be takenas it suggests that it can only be passed on once the infected animal has died — only once in alifetime, in other words.

b) Passive spread

Passive spread can take place in two ways:

- through ingestion of infectious tissue and capacity to destroy the pathological prion protein indigestive processes

- through transport in the crop, plumage, claws and beak

Large carrion birds do not normally consume bovine central nervous tissue, but do consume theirintestines and, occasionally, ovine CNS tissue (or at least the spinal medulla).

In any case it must be stressed that some less specialised species, such as corvids — which,moreover, are very numerous — are more likely to contribute to spread since one of theirfavourite foods is eyes, clearly considered to be specified risk material. Some species of rodentscould more realistically constitute carriers than could carrion birds since they can more easilyconsume nervous tissue, which is more highly contaminated.

As has already been pointed out, and although all seems to indicate the opposite, the capacity ofcarrion birds’ digestive system to destroy prion proteins has not yet been formally demonstrated:if the principle of precaution is to be applied, it must be assumed that they can act as passivevectors until it can be proven otherwise. These birds may play a relatively important part indissemination, given that they can cover great distances and may even migrate long distances.Consequently, the potential for transmission can be considered medium to high since one singlemeal could be scattered as faecal matter over several areas. Moreover, transmission would takeplace each time an individual bird ate infected tissues, which could happen several times duringits life.

As far as the transportation of contaminated material in the crop, feathers, claws and beak isconcerned, only the first appears to be of any importance since it is part of the species’ normalmethod of storing food, but might be more exceptional in other cases (except in that of thebearded vulture). Material transported in the crop is fed to chicks during the reproductive phase,if it is not digested, and thus, leaving aside any occasional wastage, enters a digestive cyclesimilar to that of adults but with the added security of by-products being confined to the nest andsurrounding areas. The potential for transmission in this manner should be considered to be low.

In all cases, the only reasonable step to take would be to monitor known and accessible sourcesof agents, namely cases of TSE in domesticated animals.

[Note: At its meetings of 25 July and 5 September 2002, the TSE/BSE ad hoc Group considered thatwith the advent of the BSE epidemic, necrophagous birds may now have the potential to ingesthighly BSE infectious materials and that this could contribute to spread of infectious tissue, as it isunlikely that the pathological prion protein will be destroyed completely in the avian alimentarytract. Further possible mechanical transport of agent could also occur in the crop, plumage, clawsand beak. Theoretically, the transportation of BSE or TSE infected materials could play arelatively important part in dissemination, given that such birds can cover great distances andmay even migrate long distances. Therefore this potential source of transmission should beeliminated, as far as is possible, by testing of all possibly TSE affected dead bovines and smallruminants and by the effective destruction of all SRM and all animals found to be positive.]

c) Exposure of persons involved in handling carrion and direct release of the agent into theenvironment

Persons involved in handling and transporting animals with BSE can be exposed to risk.Moreover, if the security of the methods of transport cannot be guaranteed, there may be lossesduring the journey. Moreover, leaving contaminated material in the natural environment impliesleaving an extremely resistant agent — and one which, it has been suggested, may contaminateaquifers — uncontrolled.

This potential source of transmission could be almost completely eliminated through tests on alldead bovines and the effective destruction of all found to be positive.

[Note: The TSE/BSE ad hoc Group at its meetings of 25 July and 25 September 2002 considered thatnecrophagous birds transporting BSE infected materials could, possibly, lead to exposure ofpersons involved in their handling and transporting. This risk can be considered to be negligible,but potential sources of transmission should be eliminated as previously suggested.]

V.5. Practical proposals for action regarding the use of carcasses from other species to feedthese birds

a) Consumption figures, vulture numbers and current status of middens

It has been determined that a single adult in captivity needs 2.5 kg of food/week for slight weightgain (Mendelsohn and Leshem, 1983) whereas in the wild and during breeding periods thisfigure can reach 3.5 kg/week. The 1999 vulture count carried out by the SEO (SociedadEspañola de Ornitología, Spanish Ornithological Society), showed that there were some 20 000pairs, with these species alone requiring some 10 000 tonnes of food each year (whichcorresponds to 15% of the biomass generated by dead domesticated animals not intended forhuman consumption). To this group must be added all of the non-breeding individuals (chicks,young birds, single adults and older birds). It must be stressed that in Spain, ovine, bovine andporcine livestock (Camiña, 1995, 1996, 2001b) would appear to be the main source of food forthese species in terms of numbers — with variations according to the species and the region —while bovines as a species provide the largest proportion of food to carrion birds in terms ofbiomass (Camiña, 2001a).

Aragón, Castille-León, Andalucía, Navarre and Castille-La Mancha are home to 80% of thepopulation of Spain’s four species of vulture. It would be necessary to carry out a detailed studyof the feeding areas of these groups relative to the numbers of domesticated animals to determinethe potential impact of the removal of ruminants, an impact which is already being felt in someareas (Camiña, 1995), and of the current systems for the disposal of carcasses from each of thedomesticated species.

At present there is a network of controlled and authorised or traditional middens, with the latterbeing making up the vast majority. Only La Rioja has passed legislation regulating the operationof middens. In other areas, such as Valencia, similar legislation has been drafted but has been puton hold because of the outbreaks of swine fever, and Castille-León and Andalucía are planningactivities along the same lines. By way of an example, SEO/Birdlife sources (Camiña, 2001a)state that there is one active, controlled feeding area in the Basque Country, three in La Rioja (atleast another four have been closed), and two in Extremadura. Illegal middens are much morenumerous and for this reason reliable information is not available. Suffice it to say thatSEO/Birdlife, through exhaustive research in other provinces, knows of at least 51 uncontrolledmiddens in just two areas of Castille-León and a further 100 in Aragón. We must point out thatsince the first cases of BSE appeared in Spain most of the controlled middens have suspendedtheir activity while awaiting new regulations and this could place the populations of carrion birdsin serious danger, both directly through lack of food and indirectly by forcing them to attackliving animals which will create an impression of danger and lead to uncontrolled retaliatoryaction from the affected sectors.

The midden system, therefore, could have great health and ecological value if developed undersuitable conditions with the appropriate financial and legal support, and could potentially lowerthe costs of disposal of SRM. Comparative studies of this matter should therefore be carried out.

b) Proposals for feeding carrion birds:

1.- Continue to use bovines:

Given that all dead animals on farms must be tested for BSE pursuant to the new regulations forthe control and eradication of this disease (Order of 26 July 2001), carcasses of animals forwhich rapid test results are negative can still be used to feed carrion birds through the simpleprovision of drop-off points where the intestines would be removed (assuming that the head hadalready been removed for the BSE tests) and kept for a few days until the results of the rapidtests are known. Carcasses could then be transported to the carrion birds’ feeding areas.

This system (without the BSE testing) had already been successfully operating in someAutonomous Communities before the BSE crisis, and the only cost increase would be generatedby the removal of the intestines and the refrigeration of the carcasses until the results of the rapidtests are known. The cost of these tests would be covered in line with European BSE regulations.In this way, processing and incineration costs would be kept low and a natural form of recyclingwould be encouraged. Additionally, this would be a much more local solution than transport toprocessing plants, and this in turn could limit the spread of other epidemiological risks linked tothe infectious causes of death of domesticated animals. The social impact of this measure wouldundoubtedly be greater than of any other. Food supply needs, behavioural guidelines and the useof space by carrion eaters would all need to be worked out beforehand to determine the finalcost, since the procedure could be limited to a specific number of cases.

The potential for BSE spread would be low.

This measure could be adopted by those ACs with high numbers of carrion eaters and lownumbers of other domesticated species.

2.- Complete elimination of use of bovines:

Carrion birds would be fed exclusively on carcasses of species not susceptible to BSE and allbovine carcasses would be systematically destroyed. This would also require an estimate of thefeeding needs and the level of supply which would be possible with other species.

This system would make the carrion eaters’ diet much less varied and we cannot say whether thiswould present any problems for them, although this cannot be ruled out either.

Costs for this alternative would mainly be generated by the transport of carcasses of thesespecies to the appropriate middens and could be relatively high. This system could,furthermore, increase the risk of other infectious disorders spreading to far-flung areas. Inany case, the costs for the removal and destruction of bovines would remain.

The potential for the spread of BSE under this system would be minimal.

This method could be used in those ACs or areas where other domesticated species notsusceptible to BSE (especially equines and porcines) are present in high numbers.

3.- Use of ovines:

At the present time, and in spite of the absence as previously mentioned of known risks linked tocarrion birds’ consumption of small ruminants with scrapie, a moratorium should be declared onthe use of sheep remains (at least those considered to be SRM) as a food source until thepossibility of the BSE agent being masked by the scrapie agent has been ruled out. For thisreason, SRM sheep remains (feeding sheep’s feet to bearded vultures, as is done in someAutonomous Communities, is probably not a high-risk practice as far as BSE spread isconcerned) should not be considered clear of uncertainties unless they have been subject to BSEtesting, which would be far more expensive than tests on bovines since the volume of foodstuffper test would be 10 times lower.

In terms of numbers, sheep make up a significant proportion of carrion birds’ diet, and theexistence of a solid basis for ruling out the presence of the BSE agent in small ruminant livestockin Spain would therefore be of great relevance to ensure the safety of their use. This becomeseven more important when one considers that these animals are present in very high numbers andthat their carcasses tend to remain in far-flung and somewhat inaccessible areas.

4.- Other considerations:

The carcasses of animals which die in inaccessible areas present a major complication, difficultto resolve under any system. In most cases death is not detected until a long time after it hastaken place, since inaccessibility makes it difficult for owners to check on their animals. In mostcases the carrion birds themselves are the first indicators that an animal has died. Thesecircumstances arise in traditional rearing conditions which are well integrated in the naturalenvironment and which also have a high ecological value. For this very reason they should beconsidered as exceptions and it can be assumed that the uncertainty surrounding BSE will also bevery low given the low probability of exposure to the BSE agent through protein-rich andexpensive feedingstuffs. To prevent this exception becoming a way to escape the controlregulations, clear guidelines on the conditions under which the non-performance of tests becauseof inaccessibility can be accepted should be drawn up.

V.6. The potential role of other wild species in the spread of TSEs

There are other species of animal, some of which are considered to be protected fauna, whichhave been documented as susceptible to TSEs, such as mustelids: these may present another,much more realistic, factor of uncertainty as far as the persistence and spread of TSEs isconcerned, since they occasionally feed on carcass remains.

One notable example is the existence of a transmissible encephalopathy in minks, which has notto date been diagnosed in wild animals (Williams et al., 2001). Cases have been observed both inEurope and in North America and have been associated with the inclusion in these animals’ dietsof sheep with scrapie (Marsh and Hanson, 1979, revised by Williams et al., 2001) and, in othercases, of cattle (Marsh et al., 1991, revised by Williams et al., 2001). This disease has amorbidity rate of 60-100% and a mortality rate of 100% during outbreaks. Animals showbehavioural changes, become aggressive and develop ataxia and somnolence. Microscopiclesions are typical of TSEs. In experiments, mink spongiform encephalopathy has beentransmitted by intracerebral injection to cattle, sheep, goats, ferrets and laboratory animals.

There is no information at present on the existence of TSEs in populations in the wild, and(unpublished) research on a small group of individual animals has so far produced only negativeresults. Serious consideration should be given to studying a number of samples high enough toproduce a reliable estimate.

As stated above, attention should also be paid to the possible role of opportunist and occasionallycarrion-eating micro-mammals, which may feed on the highly contaminated nervous tissuesinaccessible to other species.

Other carrion-eating species of the canid and felid types are not considered as important from theepidemiological point of view since either they have been demonstrated to be not verysusceptible to TSEs (canids) or it is known that their natural diet does not include ruminantremains (felids). One special case could be the Iberian lynx, which belongs to the group of felidswhich has proven susceptible to the BSE agent and whose involvement in a possible TSE cycle,however improbable, could prove disastrous for the preservation of a species which is unique inEurope and extremely endangered.

Moreover, in 1967 the first cases of a spongiform encephalopathy in cervids were described inthe United States. Clinical cases are still detected both in wild animals and in animals incaptivity. The lesional symptoms are similar to those observed in cases of BSE, as are the lesionsthemselves and the immunohistochemical reactions. Of special note is the observation of smallfibres, typical of scrapie, in brain and spleen preparations (Williams et al., 2001). No similarobservations have been made elsewhere, but this calls for special attention in the new context ofa BSE epidemic.

These species could play a role both through their own habits and as a source of food for carrionspecies.

CONCLUSIONS

The conservation of a unique biological heritage must be reconciled with TSE eradicationprogrammes to ensure the security of susceptible humans and animals. Spanish society hasalready shown its clear readiness to invest resources in nature conservation. In these times it isreasonable to assume that it will show a similar readiness to protect carrion birds from the threatpresented by the disappearance of their food sources. For this reason the following steps must betaken immediately:

1.- Ensure that carrion birds do not constitute an element of uncertainty with respect to the spread of BSE by eliminating sources of contagion:

Only use bovines which have tested negative for BSE (Order of 26 July 2001amending Royal Decree 3454/2000) for feeding carrion birds, or stop feeding themthis species

Declare a moratorium on the use of sheep to feed carrion birds until it can be clearlyestablished that they are not affected by BSE

2.- Keep in mind the uncertainties surrounding land-based carrion-eating species

The alternative of continuing to use bovines provided they have first been subjected to testsdraws directly upon current legislation concerning the eradication of BSE and would mean fewerchanges and costs relative to the pre-BSE situation, which makes it a more advisable alternative.In any case each AC should assess the specific and particular situation in each of the carrion birdhabitats in its territory. The Central Government must develop strategies for coordinationbetween the ACs on food for carrion birds, since these species can move far beyond theboundaries of the Autonomous Communities.

REFERENCES RELATING TO THE SCIENTIFIC AND TECHNICALDOCUMENTS USED IN THE PRODUCTION OF THIS REPORT

Order of 26 July 2001 amending certain annexes of Royal Decree 2454/2000 of 22 December 2000 establishing andregulating the Coordinated Integral Programme for the surveillance and control of transmissible spongiformencephalopathies in animals. State Official Gazette 179: 27523-26 (Art. No. 14641) 2001. (Orden del 26 de juliode 2001 por la que se modifican determinados anexos del Real Decreto 2454/2000 de 22 de diciembre, por el quese establece y regula el Programa Integral Coordinado de vigilancia y control de las encefalopatías espongiformestransmisibles de los animales. B.O.E., 179:27523-26 (Art. Núm. 14641) 2001.)

Brown, P., Rohwer, R.G., Green, E.M. and Gadjusek, D.C. (1986) The effect of chemicals, heat, and histopathologicprocessing on high-infectivity hamster-adapted scrapie virus. In: Virus non Conventionnels et Affections duSysteme Nerveux Central. Eds.: Court, L.A. and Cathala, F. pp 156-163. Paris. Masson

Brown, P., Wolff, A. and Gadjusek, D.C. (1990) A simple and effective method for inactivating virus infectivity informalin-fixed tissue samples from patients with Creutzfeld-Jakob disease. Neurology 40, 887-890.

Cawthorne, R.J.G. (1997) Failure to confirm a TSE [transmissible spongiform encephalopathy] in chickens. Vet.Rec. 141, 203.

Camiña, A. (1995) Explotación de carroñas por el buitre leonado y otros carroñeros menores en una zona deGanadería extensiva en La Rioja (Consumption of carrion by griffon vultures and other minor carrion eaters in alarge livestock-rearing area of La Rioja). Instituto de Estudios Riojanos. Logroño.

Camiña, A. (1996) Explotación de carroñas por el buitre leonado y otros carroñeros menores. II: El papel de losmuladares.(Consumption of carrion by griffon vultures and other minor carrion eaters, II: the role of middens)Instituto de Estudios Riojanos. Logroño.

Camiña, A. (2001a) Incidencia del programa integral coordinado de vigilancia y control de la encefalopatíasespongiformes transmissibles (EETs) (3454/2000) en las aves carroñeras de España (Consideracionespreliminares). Version 26 de marzo de 2001. Informe para el Grupo de Rapaces de SEO/Birdlife. Madrid. (Effectof the coordinated programme for TSE surveillance and monitoring on carrion birds in Spain (primaryconsiderations). Version of 26 March 2001. Report for the SEO/Birdlife Birds of Prey Group)

Camiña, A. (2001b) Incidencia de la EEB en los parámetros reproductores y en la alimentación del buitre leonado enLa Rioja. Temporada de cría 2001. (Effect of BSE on reproduction parameters and on feeding habits of thegriffon vulture in La Rioja. 2001 breeding season). Informe para la Dirección General del Medio Natural.Consejería de Turismo y Medio Ambiente. Gobierno de La Rioja.

Dawson, M., Wells, G.A.H., Parker, B.N.J. and Scott, A.C. (1991) Transmission studies of BSE in cattle, hamsters,pigs and domestic fowl. In: Sub-acute spongiform encephalopathies., Eds. Bradley, R.; Savey, M. and Marchant,B. Brussels, 12-14 November 1990. pp. 25-32; Cur. Top. Vet. Med. Anim. Sci. 55. Kluwer Academic Publishers.Dordrecht, The Netherlands.

Farner, D.S. (1967) The hydrogen ion concentration in avian digestive tracts. Poultry Sci. 21, 445.

Gabriel, J.M., Oesch, B., Kretzschmar, H., Scott, M. and Prusiner, S.B. (1992) Molecular cloning of a candidatechicken prion protein. Proc. Natl. Acad. Sc. USA 89, 9097-9101.

Houston, D.C. and Cooper, J.E. (1975) The digestive tract of the whiteback griffon vulture and its role in diseasetransmission among wild ungulates. J. Wildlife Dis.11, 306-313.

Mendelsohn, H. and Leshem, Y. (1983) Observations on reproduction and growth of Old World vulture. In: VultureBiology and Management. Eds. Wilbur, S.R. and Jackson, J.A. University of California Press. Berkley.

Ministerio de Agricultura, Pesca y Alimentación (2000) Secretaría General Técnica. Censos y produccionesganaderas. Hechos y cifras del Sector Agroalimentario Español. (Livestock counts and production. Facts andfigures from the Spanish agri-food sector)

Marsh, R.F. and Hanson, R.P. (1979) On the origin of transmissible mink encephalopathy. In: Slow transmissiblediseases of the nervous system, vol 1. Ed. S.B. Prusiner and W.J, Hadlow. New York: Academic, pp. 451-460.

Marsh, R.F., Bessen, R.A., Lehmann, S. and Hartsough, G.R. (1991) Epidemiological and experimental studies on anew incident of transmissible mink encephalopathy. J.Gen.Vir. 72, 589-594.

Mould, D.L., Dawson, A.M. and Smith, W. (1965) Scrapie in mice. The stability of the agent to various suspendingmedia, pH and solvent extraction. Res.Vet. Sci.6, 151-154.

Narang, H. (1997) Failure to confirm a TSE [transmissible spongiform encephalopathy] in chickens. Vet.Rec. 141,255-256.

Schoon, H.A., Brunckhorst, D. and Pohlenz, J. (1991) Spongiform encephalopathy in an ostrich (Struthio camelus).A case report. Tierarztl. Prax. 19, 263-265.

Taylor, D.M. (1995) Survival of mouse-passaged bovine spongiform encephalopathy agent after exposure toparaformaldehyde-lysine-periodate and formic acid. Vet. Microbiol. 44, 111-112.

Taylor, D.M. (2000) Inactivation of transmissible degenerative encephalopathy agents: a review. Vet.J. 159, 10-17.

Taylor, D.M., Brown, J.M., Fernie, K. and McConnell, I. (1997) The effect of formic acid on BSE and scrapieinfectivity in fixed and unfixed brain-tissue. Vet. Microbiol. 58, 167-174.

Williams, E.S., Kirkwood, J.K. and Miller, M.W. (2001) Transmissible spongiform encephalopathies. En Infectiousdiseases of wild mammals. Ed. Williams, E.S. and Barker, I.K. Published by Manson Publishing.

Wopfner, F., Weidenhofer, G., Schneider, R., von-Brunn, A., Gilch, S., Schwarz, T.F., Werner, T. and Schatzl, H.M.(1999) Analysis of 27 mammalian and 9 avian PrPs reveals high conservation of flexible regions of the prionprotein. J. Mol. Biol. 289, 1163-1178.

ANNEX I. CARRION BIRD NUMBERS

1. Carrion birds

Griffon vulture (Gyps fulvus): 17 500 breeding pairs, representing 85-95% of Europe’spopulation

Black vulture (Aegypius monachus): 1200 pairs, 98% of Europe’s population

Egyptian vulture (Neophron percnopterus): 1300 pairs, 80% of Europe’s population

Bearded vulture (Gypaetus barbatus) (endangered). The entire European population hasbeen reduced to 77 pairs in the Spanish Pyrenees and 23 in the French Pyrenees

2. Birds which occasionally eat carrion

Spanish imperial eagle (Aquila adalberti): 130 pairs. (100%) Spain is the only place inthe world where this endangered species is found

Golden eagle (Aquila chrysaetos): 1200 pairs, 20% of Europe’s population

Red kite (Milvus milvus): 9000 pairs, 18 % of Europe’s population

Black kite (Milvus migrans): 3500 pairs, 7%, although 80% of Europe’s populationoverwinters in Spain

ANNEX II. SPECIFIC INFORMATION REQUIRED

It is extremely important to consolidate the hypotheses put forward in this report, which will callfor some observations to be expanded upon and some points to be verified. For this reason,specific research into the following areas will need to be carried out as soon as possible:

an inventory of feeding points for carrion birds, carcass dumps and middens

a comparison of the cost of disposing of carcasses by processing and incineration againstBSE testing and feeding carrion birds

research into the true incidence of scrapie in Spain and characterisation of the strains of theagent involved in all cases.

Research into carrion birds’ susceptibility to TSEs and their capacity for destroyingpathological prion proteins through digestion.

Research into other potential factors for TSE transmission in the environment

The ecological impact of any health measures for the control and eradication of TSEs.

https://food.ec.europa.eu/document/download/de9cce2f-736c-4875-ae4b-77f105cd6639_en?filename=sci-com_ssc_out295_en.pdf&prefLang=ga

SUNDAY, NOVEMBER 01, 2009

American crows (Corvus brachyrhynchos) and potential spreading of CWD through feces of digested infectious carcases

Could Crows Play a Role in Spreading CWD

was presented by Dr. Kurt VerCauteren, NWRC, WS-APHIS- USDA.

or down further too;

as the crow flies, Jimmy crack corn, and they don't care CWD

thought some of you here might find interest in this...

Prion. 2013 Jul 3;7(4). [Epub ahead of print]

Could avian scavengers translocate infectious prions to disease-free areas initiating new foci of chronic wasting disease?

see in this link the history of 'as the crow flies' so does cwd...terry

FRIDAY, MARCH 24, 2023

Mountain lions, Wolves, Coyotes, could help stop the spread of CWD TSE Prion in deer, WHERE STUPID MEETS THE ROAD!

https://transmissiblespongiformencephalopathy.blogspot.com/2023/03/mountain-lions-wolves-coyotes-could.html 

Sunday, November 01, 2009

AS THE CROW FLIES, SO DOES CWD

American crows (Corvus brachyrhynchos) and potential spreading of CWD through feces of digested infectious carcases

http://chronic-wasting-disease.blogspot.com/2009/11/american-crows-corvus-brachyrhynchos.html

Monday, July 13, 2009

Deer Carcass Decomposition and Potential Scavenger Exposure to Chronic Wasting Disease

http://chronic-wasting-disease.blogspot.com/2009/07/deer-carcass-decomposition-and.html

Sunday, July 07, 2013

Could avian scavengers translocate infectious prions to disease-free areas initiating new foci of chronic wasting disease?

Prion. 2013 Jul 3;7(4). [Epub ahead of print]

http://chronic-wasting-disease.blogspot.com/2013/07/could-avian-scavengers-translocate.html

another fine example letter. this one will floor you. 'Jimmy crack corn, and they don't care' no big deal, just flush those mixers with corn, then feed the corn to the deer. NOooooo problem.

Subject: ''MORE'' 'VIOLATORS' of Animal Proteins Prohibited in Ruminant Feed--U.S.A. (more and more MAD COW FEED RULES BROKEN IN U.S.A.]

Date: Tue, 24 Apr 2001 09:45:15 –0700

From: "Terry S. Singeltary Sr."

Reply-To: Bovine Spongiform Encephalopathy

To: BSE-L@uni-karlsruhe.de References: 1 , 2

######### Bovine Spongiform Encephalopathy #########

Greetings again List Members,

''MORE'' violations and warning letters over FDA MAD COW feed ban regulations that have not been complied with since the Aug. 4, 1997 'partial' feed ban was implemented...

they implemented something, then forgot to enforce it $$$$$

another fine example letter. this one will floor you. 'Jimmy crack corn, and they don't care' no big deal, just flush those mixers with corn, then feed the corn to the deer. NOooooo problem.

these people must be brain dead???

DEPARTMENT OF HEALTH & HUMAN SERVICES PUBLIC HEALTH SERVICE FOOD AND DRUG ADMINISTRATION

April 9, 2001 WARNING LETTER

01-PHI-12 CERTIFIED MAIL RETURN RECEIPT REQUESTED

Brian J. Raymond, Owner Sandy Lake Mills 26 Mill Street P.O. Box 117 Sandy Lake, PA 16145 PHILADELPHIA DISTRICT

Tel: 215-597-4390

Dear Mr. Raymond:

Food and Drug Administration Investigator Gregory E. Beichner conducted an inspection of your animal feed manufacturing operation, located in Sandy Lake, Pennsylvania, on March 23, 2001, and determined that your firm manufactures animal feeds including feeds containing prohibited materials. The inspection found significant deviations from the requirements set forth in Title 21, code of Federal Regulations, part 589.2000 - Animal Proteins Prohibited in Ruminant Feed. The regulation is intended to prevent the establishment and amplification of Bovine Spongiform Encephalopathy (BSE) . Such deviations cause products being manufactured at this facility to be misbranded within the meaning of Section 403(f), of the Federal Food, Drug, and Cosmetic Act (the Act).

Our investigation found failure to label your swine feed with the required cautionary statement "Do Not Feed to cattle or other Ruminants" The FDA suggests that the statement be distinguished by different type-size or color or other means of highlighting the statement so that it is easily noticed by a purchaser.

In addition, we note that you are using approximately 140 pounds of cracked corn to flush your mixer used in the manufacture of animal feeds containing prohibited material. This flushed material is fed to wild game including deer, a ruminant animal. Feed material which may potentially contain prohibited material should not be fed to ruminant animals which may become part of the food chain.

The above is not intended to be an all-inclusive list of deviations from the regulations. As a manufacturer of materials intended for animal feed use, you are responsible for assuring that your overall operation and the products you manufacture and distribute are in compliance with the law. We have enclosed a copy of FDA's Small Entity Compliance Guide to assist you with complying with the regulation... blah, blah, blah...

http://www.fda.gov/foi/warning_letters/g1115d.pdf

http://web.archive.org/web/20061006131215/http://www.fda.gov/foi/warning_letters/g1115d.pdf

-------- Original Message --------

Subject: MAD DEER FEED BAN WARNING LETTER RECALL 6 TONS DISTRIBUTED USA

Date: Wed, 20 Oct 2004 14:53:56 –0500

From: "Terry S. Singeltary Sr." flounder@WT.NET

Reply-To: Bovine Spongiform Encephalopathy BSE-L@UNI-KARLSRUHE.DE

To: BSE-L@UNI-KARLSRUHE.DE

##################### Bovine Spongiform Encephalopathy #####################

PRODUCT

Product is __custom made deer feed__ packaged in 100 lb. poly bags. The product has no labeling. Recall # V-003-5.

CODE

The product has no lot code. All custom made feed purchased between June 24, 2004 and September 8, 2004.

RECALLING FIRM/MANUFACTURER

Farmers Elevator Co, Houston, OH, by telephone and letter dated September 27, 2004. Firm initiated recall is ongoing.

REASON

Feed may contain protein derived from mammalian tissues which is prohibited in ruminant feed.

VOLUME OF PRODUCT IN COMMERCE

Approximately 6 tons.

DISTRIBUTION OH.

END OF ENFORCEMENT REPORT FOR October 20, 2004

http://www.fda.gov/TSS

################# BSE-L-subscribe-request@uni-karlsruhe.de #################

now, just what is in that deer feed? _ANIMAL PROTEIN_

Subject: MAD DEER/ELK DISEASE AND POTENTIAL SOURCES

Date: Sat, 25 May 2002 18:41:46 –0700

From: "Terry S. Singeltary Sr."

Reply-To: BSE-L

To: BSE-L

8420-20.5% Antler Developer For Deer and Game in the wild Guaranteed Analysis Ingredients / Products Feeding Directions

snip...

_animal protein_

http://www.surefed.com/deer.htm

REFERENCES

snip...see full text ;

-------- Original Message --------

Subject: DOCKET-- 03D-0186 -- FDA Issues Draft Guidance on Use of Material From Deer and Elk in Animal Feed; Availability

Date: Fri, 16 May 2003 11:47:37 –0500

From: "Terry S. Singeltary Sr." To: fdadockets@oc.fda.gov

Greetings FDA,

i would kindly like to comment on;

Docket 03D-0186

FDA Issues Draft Guidance on Use of Material From Deer and Elk in Animal Feed; Availability

http://madcowfeed.blogspot.com/2008/07/docket-03d-0186-fda-issues-draft.html

terry