BMC Veterinary Research 2013, 9:134 doi:10.1186/1746-6148-9-134
Published: 9 July 2013
Rapid assessment of bovine spongiform encephalopathy prion inactivation by heat treatment in yellow grease produced in the industrial manufacturing process of meat and bone meals
Miyako Yoshioka1,2 Email: firstname.lastname@example.org Yuichi Matsuura1 Email: email@example.com Hiroyuki Okada1 Email: firstname.lastname@example.org Noriko Shimozaki1 Email: email@example.com Tomoaki Yamamura1 Email: firstname.lastname@example.org Yuichi Murayama1* * Corresponding author Email: email@example.com Takashi Yokoyama1 Email: firstname.lastname@example.org Shirou Mohri1
1 Research Area of Pathology and Pathophysiology, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan
2 Prion Disease Research Center, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan
Prions, infectious agents associated with transmissible spongiform encephalopathy, are primarily composed of the misfolded and pathogenic form (PrPSc) of the host-encoded prion protein. Because PrPSc retains infectivity after undergoing routine sterilizing processes, the cause of bovine spongiform encephalopathy (BSE) outbreaks are suspected to be feeding cattle meat and bone meals (MBMs) contaminated with the prion. To assess the validity of prion inactivation by heat treatment in yellow grease, which is produced in the industrial manufacturing process of MBMs, we pooled, homogenized, and heat treated the spinal cords of BSE-infected cows under various experimental conditions.
Prion inactivation was analyzed quantitatively in terms of the infectivity and PrPSc of the treated samples. Following treatment at 140°C for 1 h, infectivity was reduced to 1/35 of that of the untreated samples. Treatment at 180°C for 3 h was required to reduce infectivity. ***However, PrPSc was detected in all heat-treated samples by using the protein misfolding cyclic amplification (PMCA) technique, which amplifies PrPSc in vitro. Quantitative analysis of the inactivation efficiency of BSE PrPSc was possible with the introduction of the PMCA50, which is the dilution ratio of 10% homogenate needed to yield 50% positivity for PrPSc in amplified samples.
Log PMCA50 exhibited a strong linear correlation with the transmission rate in the bioassay; infectivity was no longer detected when the log PMCA50 of the inoculated sample was reduced to 1.75. The quantitative PMCA assay may be useful for safety evaluation for recycling and effective utilization of MBMs as an organic resource.
Prion inactivation, Bovine spongiform encephalopathy, Meat and bone meal, Yellow grease, Infectivity, Protein misfolding cyclic amplification
Chronic Wasting Disease CWD, and other TSE prion disease, these TSE prions know no borders.
these TSE prions know no age restrictions.
The TSE prion disease survives ashing to 600 degrees celsius, that’s around 1112 degrees farenheit.
you cannot cook the TSE prion disease out of meat.
you can take the ash and mix it with saline and inject that ash into a mouse, and the mouse will go down with TSE.
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production as well.
the TSE prion agent also survives Simulated Wastewater Treatment Processes.
IN fact, you should also know that the TSE Prion agent will survive in the environment for years, if not decades.
you can bury it and it will not go away.
The TSE agent is capable of infected your water table i.e. Detection of protease-resistant cervid prion protein in water from a CWD-endemic area.
it’s not your ordinary pathogen you can just cook it out and be done with. that’s what’s so worrisome about Iatrogenic mode of transmission, a simple autoclave will not kill this TSE prion agent.
I go from state to state trying to warn of the CWD and other TSE prion disease in other species, I just made a promise to mom. back then, there was no information.
so, I submit this to you all in good faith, and hope that you take the time to read my research of the _sound_, peer review science, not the junk science that goes with the politics $$$
right or left or teaparty or independent, you cannot escape the TSE prion disease.
there is a lot of science here to digest, but better digesting this _sound_ science, instead of the junk political science you will hear from the shooting pen industry.
I don’t care what you eat, or what party you are affiliated with, my problem is, when you consume these TSE prions, and then go enter the medical, surgical, dental, blood and tissue arena, then you risk exposing _me or MY_ family to the TSE prion disease via friendly fire, the pass it forward mode of transmission mission, or what they call iatrogenic CJD. all iatrogenic CJD is, is sporadic CJD, until the route and source of the TSE prion agent is proven.
I am NOT anti-hunter, I am or was a hunter (disabled with neck injury and other medical problems), I am a meat eater.
I just don’t care for stupid, and sometimes you just can’t fix stupid, Lord knows I have tried.
I do NOT advertise on these blogs, they are there for educational use. ...
New studies on the heat resistance of hamster-adapted scrapie agent: Threshold survival after ashing at 600°C suggests an inorganic template of replication
The infectious agents responsible for transmissible spongiform encephalopathy (TSE) are notoriously resistant to most physical and chemical methods used for inactivating pathogens, including heat. It has long been recognized, for example, that boiling is ineffective and that higher temperatures are most efficient when combined with steam under pressure (i.e., autoclaving). As a means of decontamination, dry heat is used only at the extremely high temperatures achieved during incineration, usually in excess of 600°C. It has been assumed, without proof, that incineration totally inactivates the agents of TSE, whether of human or animal origin.
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production
Histochemical analysis of hamster brains inoculated with the solid residue showed typical spongiform degeneration and vacuolation. Re-inoculation of these brains into a new cohort of hamsters led to onset of clinical scrapie symptoms within 75 days, suggesting that the specific infectivity of the prion protein was not changed during the biodiesel process. The biodiesel reaction cannot be considered a viable prion decontamination method for MBM, although we observed increased survival time of hamsters and reduced infectivity greater than 6 log orders in the solid MBM residue. Furthermore, results from our study compare for the first time prion detection by Western Blot versus an infectivity bioassay for analysis of biodiesel reaction products. We could show that biochemical analysis alone is insufficient for detection of prion infectivity after a biodiesel process.
Detection of protease-resistant cervid prion protein in water from a CWD-endemic area
The data presented here demonstrate that sPMCA can detect low levels of PrPCWD in the environment, corroborate previous biological and experimental data suggesting long term persistence of prions in the environment2,3 and imply that PrPCWD accumulation over time may contribute to transmission of CWD in areas where it has been endemic for decades. This work demonstrates the utility of sPMCA to evaluate other environmental water sources for PrPCWD, including smaller bodies of water such as vernal pools and wallows, where large numbers of cervids congregate and into which prions from infected animals may be shed and concentrated to infectious levels.
A Quantitative Assessment of the Amount of Prion Diverted to Category 1 Materials and Wastewater During Processing
Keywords:Abattoir;bovine spongiform encephalopathy;QRA;scrapie;TSE
In this article the development and parameterization of a quantitative assessment is described that estimates the amount of TSE infectivity that is present in a whole animal carcass (bovine spongiform encephalopathy [BSE] for cattle and classical/atypical scrapie for sheep and lambs) and the amounts that subsequently fall to the floor during processing at facilities that handle specified risk material (SRM). BSE in cattle was found to contain the most oral doses, with a mean of 9864 BO ID50s (310, 38840) in a whole carcass compared to a mean of 1851 OO ID50s (600, 4070) and 614 OO ID50s (155, 1509) for a sheep infected with classical and atypical scrapie, respectively. Lambs contained the least infectivity with a mean of 251 OO ID50s (83, 548) for classical scrapie and 1 OO ID50s (0.2, 2) for atypical scrapie. The highest amounts of infectivity falling to the floor and entering the drains from slaughtering a whole carcass at SRM facilities were found to be from cattle infected with BSE at rendering and large incineration facilities with 7.4 BO ID50s (0.1, 29), intermediate plants and small incinerators with a mean of 4.5 BO ID50s (0.1, 18), and collection centers, 3.6 BO ID50s (0.1, 14). The lowest amounts entering drains are from lambs infected with classical and atypical scrapie at intermediate plants and atypical scrapie at collection centers with a mean of 3 × 10−7 OO ID50s (2 × 10−8, 1 × 10−6) per carcass. The results of this model provide key inputs for the model in the companion paper published here.
Subject: OPINION ON THE USE OF BURIAL FOR DEALING WITH ANIMAL CARCASSES AND OTHER ANIMAL MATERIALS THAT MIGHT CONTAIN BSE/TSE
Date: Wed, 22 Jan 2003 14:58:53 –0600
From: "Terry S. Singeltary Sr."
Reply-To: Bovine Spongiform Encephalopathy To: BSE-L@uni-karlsruhe.de
######## Bovine Spongiform Encephalopathy #########
EUROPEAN COMMISSION HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL Directorate C - Scientific Opinions C1 - Follow-up and dissemination of scientific opinions OPINION ON THE USE OF BURIAL FOR DEALING WITH ANIMAL CARCASSES AND OTHER ANIMAL MATERIALS THAT MIGHT CONTAIN BSE/TSE ADOPTED BY THE SCIENTIFIC STEERING COMMITTEE MEETING OF 16-17 JANUARY 2003 1 OPINION On 17 May 2002, the Scientific Steering Committee (SSC) was invited by Commission Services to advice on the examples of conditions under which safe burial of potentially TSE-infected (animal) materials can be achieved. The details of the SSC's evaluation are provided in the attached report. The SSC concludes as follows: (1) The term "burial" includes a diversity of disposal conditions. Although burial is widely used for disposal of waste the degradation process essential for BSE/TSE infectivity reduction is very difficult to control. The extent to which such an infectivity reduction can occur as a consequence of burial is poorly characterised. It would appear to be a slow process in various circumstances. (2) A number of concerns have been identified including potential for groundwater contamination, dispersal/transmission by birds/animals/insects, accidental uncovering by man. (3) In the absence of any new data the SSC confirms its previous opinion that animal material which could possibly be contaminated with BSE/TSEs, burial poses a risk except under highly controlled conditions (e.g., controlled landfill). The SSC reiterates the consideration made in its opinion of 24-25 June 1999 on "Fallen Stock"1. The limited capacity for destruction of animal wastes in certain countries or regions in the first place justifies the installation of the required facilities; it should not be used as a justification for unsafe disposal practices such as burial. However, the SSC recognises that for certain situations or places or for certain diseases (including animals killed and recycled or disposed of as a measure to control notifiable diseases), the available rendering or incinerator or disposal capacity within a region or country could be a limiting factor in the control of a disease. Thus if hundreds or even millions of animals need to be rendered after killing or if the transport of a material to a rendering or disposal plant proved to be impractical, an appropriate case by case risk assessment2 should be carried out before deciding upon the most appropriate way of disposal. In principle, the risk is expected to be the lower for small incinerators3 as compared to burial. As such decisions in practice may have to be taken at very short notice, risk management scenarios according to various possible risks should be prepared in advance to allow for a rapid decision when the need arises.
1 Scientific Opinion on The risks of non conventional transmissible agents, conventional infectious agents or other hazards such as toxic substances entering the human 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. Adopted By the Scientific Steering Committee at its meeting of 24-25 June 1999. (and re-edited at its meeting of 22-23 July 1999). 2 See also the relevant sections and footnotes on risk assessment in the report accompanying the SSC opinion of 24-25 June 1999. 3 See SSC opinion of 16-17 January 2003 on the use of small incinerators for BSE risk reduction. 2
THE USE OF BURIAL FOR DEALING WITH CARCASSES AND OTHER MATERIALS THAT MIGHT CONTAIN BSE/TSE REPORT
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by Commission Services to advice on the examples of conditions under which safe burial of potentially TSE-infected animal materials can be achieved. The SSC appointed Prof.J.Bridges as rapporteur. His report was discussed and amended by the TSE/BSE ad hoc Group at its meeting of 9 January 2003 and by the SSC at its meeting of 16-17 January 2003.
2. GENERAL CONSIDERATIONS
"Burial" covers a range of disposal situations ranging from the practice of burying animals on farms and other premises in a relatively shallow trench (with or without treatment such as lining) to deep disposal to a lined and professionally managed landfill site (SSC 2001). Buried organic material is normally decomposed by microbial and chemical processes. However this is not a process amenable to control measures. As noted by the SSC "Opinion on Fallen Stock" (SSC 25th June 1999) there is little reliable information on the extent and rate of infectivity reduction of BSE/TSEs following burial. An old paper by Brown and Gajdusek 1991 assumed a reduction of 98% over 3 years. However it is noted that the rate of degradation of materials following burial can vary very considerably between sites. This is not surprising because the degradation process is strongly influenced by factors such as water content of the site, temperature inside the site, nature of adsorptive "material" present etc. The previous SSC opinion noted that BSE/TSEs appear to be resistant to degradation when stored at room temperature over several years. It also raised concerns that mites could serve as a vector and/or reservoir for the infected scrapie material. Burial sites may have a thriving animal population. Uncovering of risk material that is not deeply buried is therefore possible. The SSC in its opinion of 28th-29th June 2001 set out a framework for assessing the risk from different waste disposal processes. These criteria may be applied to burial as follows:
(1) Characterisation of the risk materials involved.
Unlike many other waste disposal options there are no technical or economic factors that would limit the nature of the material that can be disposed of by burial. Moreover in many cases the location of burial sites is uncertain. The potential for transmission of BSE/TSEs for SRM that is buried near the surface is also poorly characterised.3
(2) Risk reduction.
The extent to which the infectivity is reduced is likely to vary substantially according to the nature of the site depth of burial whether pre-treatment by burning or through the addition of lime is used etc. There appears to be no scientific basis at present for the prediction of the rate of loss of infectivity. In the absence of such data, as a worst case, it has to be assumed that over a three-five year period the loss of infectivity may be slight. In principle on a well-managed fully contained landfill the risks from infective material can approach zero. However this requires rigorous management over many years. This is difficult to guarantee.
(3) Degree to Which the Risks can be Contained
The principal concerns are:
* Prevention of access to the SRM by animals that could result in the transmission (directly or indirectly) of the BSE/TSE.
* Penetration of prions into the leachate/groundwater. It is noted that on some landfill sites leachate is sprayed into the air to facilitate oxidation of some organic components. Such a practice could in principle lead to dispersal of BSE/TSEs. It is also noted that it is not uncommon for landfill sites to be re-engineered to increase their stability, gas and leachate flow and/or total capacity. If this re-engineering involved an area where previous burial of BSE/TSE contaminated material had taken place and additional risk could accrue. The possibility of contaminated material being dug up in shallow and unmarked burial sites on farms etc constitutes a considerably greater risk.
3. FURTHER INVESTIGATIONS
Research is needed on specific aspects of the behaviour of prion like molecules in controlled landfills i.e.:
* Potential for adsorption to other material present in the waste that might limit their mobility.
* Principal factors influencing rates of degradation.
* Effectiveness of encasement in cement in controlling/reducing the risk.
In the absence of new evidence the opinion of the SSC "Opinion on Fallen Stock" (SSC 25th June 1999) must be endorsed strongly that land burial of all animals and material derived from them for which there is a possibility that they could incorporate BSE/TSEs poses a significant risk. Only in exceptional circumstances where there could be a considerable delay in implementing a safe means of disposal should burial of such materials be considered. Guidelines should be made available to aid on burial site selection.
EUROPEAN COMMISSION HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL Directorate C - Scientific Opinions C1 - Follow-up and dissemination of scientific opinions
OPEN BURNING OF POTENTIALLY TSE-INFECTED ANIMAL MATERIALS
ADOPTED BY THE SCIENTIFIC STEERING COMMITTEE AT ITS MEETING OF 16-17 JANUARY 2003
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by Commission Services to advice on the examples of conditions under which safe burning of potentially TSE-infected (animal) materials can be achieved. The details of the SSC's evaluation are provided in the attached report. The SSC concludes as follows:
(1) "Burning" covers a wide variety of combustion conditions. This opinion is concerned with the process of open burning e.g. bonfires.
(2) There are serious concerns regarding the use of open burning for the destruction of pathogen contaminated animal waste, particularly for waste which may be contaminated with relatively heat stable pathogens. Issues include: the potentially very high variability of the pathogen inactivation, the nature of the gaseous and particulate emissions, and the risks from the residual ash.
(3) The SSC recommends that open burning is only considered for pathogen destruction under exceptional circumstances following a specific risk assessment. In the case of animal waste possibly contaminated with BSE/TSE in view of the uncertainty of the risk open burning should be considered a risk. Suitable monitoring methods for TSE contamination of both air and ash are needed. Protocols for safe burning in emergency situations need to be established. The SSC reiterates the consideration made in its opinion of 24-25 June 1999 on "Fallen Stock"1. The limited capacity for destruction of animal wastes in certain countries or regions in the first place justifies the installation of the required facilities; it should not be used as a justification for unsafe disposal practices such as burial. However, the SSC recognises that for certain situations or places or for certain diseases (including animals killed and recycled or disposed of as a measure to control notifiable diseases), the available rendering or incinerator or disposal capacity within a region or country could be a limiting factor in the control of a disease. Thus if hundreds or even millions of animals need to be rendered after killing or if the transport of a material to a rendering or disposal plant proved to be impractical, an appropriate case by case risk assessment2 should be carried out before deciding upon the most appropriate way of disposal. In principle, the risk is expected to be the lower for small incinerators3 as compared to open burning. As such decisions in practice may have to be taken at very short notice, risk management scenarios according to various possible risks should be prepared in advance to allow for a rapid decision when the need arises. 1 Scientific Opinion on The risks of non conventional transmissible agents, conventional infectious agents or other hazards such as toxic substances entering the human 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. Adopted By the Scientific Steering Committee at its meeting of 24-25 June 1999. (and re-edited at its meeting of 22-23 July 1999). 2 See also the relevant sections and footnotes on risk assessment in the report accompanying the SSC opinion of 24-25 June 1999. 3 See SSC opinion of 16-17 January 2003 on the use of small incinerators for BSE risk reduction. 3
OPEN BURNING OF POTENTIALLY TSE-INFECTED ANIMAL MATERIALS REPORT
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by Commission Services to advice on the examples of conditions under which safe burning of potentially TSE-infected animal materials can be achieved. The SSC appointed Prof.J.Bridges as rapporteur. His report was discussed and amended by the TSE/BSE ad hoc Group at its meeting of 9 January 2003 and by the SSC at its meeting of 16-17 January 2003.
2. GENERAL CONSIDERATIONS
Burning is a combustion process to which a range of control measures may be applied to contain emissions and to ensure the completeness of the degradation process for organic matter. Depending on the source (waste) material the burning process may or may not require addition of other energy sources. Incineration/pyrolysis are contained combustion processes are contained combustion processes and therefore have the potential for a high level of control. (However see opinion on small incinerators). At the other end of the control spectrum is open burning; such as bonfires. Typically combustion of animal waste requires the addition of a high calorific fuel in order to initiate (and for some materials to sustain) the process. It is recognised that open burning of animal waste is a very cheap and convenient method of disposal. However uncontained burning has a number of problems in terms of the potential risks involved:
(1) In the open burning situation a range of temperatures will be encountered. It is difficult therefore to ensure complete combustion of the animal waste. If the waste is contaminated with pathogens there will remain considerable uncertainty as to the degree of their inactivation.
(2) Gaseous and particulate emissions to the atmosphere will occur and consequently worker and public exposure is likely. There is very little data to indicate whether or not some pathogens could be dispersed to air as a consequence of open burning.
(3) The supporting/secondary fuel may be a source of contamination itself. For example in the recent foot and mouth disease outbreak in the UK timbers were used at some sites that were heavily contaminated with pentachlorophenol.
(4) The residual ash must be considered to be a risk source. Its safe disposal needs to be assured (see opinion on small incinerators) to prevent human and animal contact and protect from groundwater contamination. While careful selection of burning sites can reduce the risks open burning should only be considered in emergency situations. For each such emergency situation a specific risk assessment should be conducted which must include the risk 4 from the pathogen of immediate concern but also other pathogens that might be present.
3. RISK ASSESSMENT OF OPEN BURNING FOR BSE
The SSC, at its meeting of 28th-29th June 2001, recommended "a framework for the assessment of the risk from different options for the safe disposal or use of meat and bone meal (MBM) and other products which might be contaminated with TSEs and other materials. Applying the framework to the practice of open burning, the following conclusions can be drawn:
3.1. Nature of the materials handled Potentially a wide variety of materials can be used provided suitable secondary fuel is available. The burning process is very simple in principle and difficult in practice to regulate effectively.
3.2. Risk reduction due to open burning There is no reliable data to indicate the extent of risk reduction that could be achieved by open burning. It is reasonable however to assume that overall it will be rather less effective in reducing the infectivity of BSE/TSE than wellconducted incineration. Moreover the reproducibility of the risk reduction is likely to be very variable even at a single location.
3.3. Airborne emissions and residue ash The composition of airborne emissions and residue ash is rarely monitored. From a risk assessment viewpoint particular attention needs to be given to the potential for the airborne dispersal of relatively heat stable pathogens as a consequence of open burning. In the absence of reliable data both airborne emissions and residual ash must be considered to constitute a significant risk if animal waste that might be contaminated with TSEs is being burnt.
4. FURTHER INVESTIGATION
Research is needed particularly on: * The potential for airborne dispersal of relatively heat stable pathogens. * Methodologies to improve the efficacy of the combustion process to ensure the inactivation of pathogen contaminated animal waste.
Open burning potentially represents a significant risk where the animal waste has the possibility of being contaminated with BSEs/TSEs. Suitable monitoring methods for TSE contamination of both air and ash are needed. Protocols for safe burning in emergency situations need to be established.
EUROPEAN COMMISSION HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL
Directorate C - Scientific Opinions C1 - Follow-up and dissemination of scientific opinions OPINION ON
THE USE OF SMALL INCINERATORS FOR BSE RISK REDUCTION
SCIENTIFIC STEERING COMMITTEE MEETING OF 16-17 JANUARY 2003
2 OPINION On 17 May 2002, the Scientific Steering Committee (SSC) was invited by Commission Services to (i) evaluate a risk assessment1 prepared for the UK's Spongiform Encephalopathy Advisory Committee (SEAC), on the potential risk arising from the use of small incinerators to dispose of specified risk materials and (ii) to advise on the safety with regard to TSE risks of the use of such small incinerators.
The details of the SSC's evaluation are provided in the attached report. The SSC concludes as follows:
(i) The SSC, at its meeting of 28th -29th June 2001, recommended "a framework for the assessment of the risk from different options for the safe disposal or use of meat and bone meal (MBM) and other products which might be contaminated with TSEs and other materials." This framework comprised five components:
(1) Identification and characterisation of the risk materials involved, the possible means for their transmission and potential at risk groups.
(2) The risk reduction achieved by the particular process.
(3) The degree to which the risks can be contained under both normal and emergency operating conditions. This inevitably includes consideration of the effectiveness of control measures.
(4) Identification of interdependent processes for example transport, storage, loading of any TSE related risk materials.
(5) The intended end-use of the products for example disposal, recycling etc. The risk assessment prepared for SEAC focuses on the risks involved steps 1 and 2 in respect of BSE/TSEs only and is based on a visit to 10 incinerators out of a total of 263 in the UK of which 60% had after burners. The risk assessment is also using a number of assumptions and data that may be valid for certain incinerator types under certain conditions, but are not necessarily applicable either for all types of materials to be disposed of, or to the whole range of types of small incinerators in use the EU and the UK.
(ii) Small incinerators are widely used to meet the needs of local communities. These incinerators vary greatly in their design, nature of use and performance characteristics and the quality of their management. As a consequence of this variability there are many uncertainties in identifying risks posed by small incinerators that are used to treat SRM materials and each type should eventually receive its own assessment. Also, general operating and control criteria should be established for
1 DNV Consulting (Det Norske Veritas), 2001. Risk assessment of SRM incinerators. Prepared for the UK Ministry of Agriculture, Fisheries and Food. Revision 2 of the Draft report, February 2001. 24 pages. 3
Potential risk sources arising from the incineration process include: gaseous emissions and residual ash. Research is currently ongoing mimicking incineration of TSE-infected brain tissue to assess the infectivity clearance level under various scenarios2. However, there are no final reported measurements that enable the risk to be assessed from either the emissions or the ash from small incinerators. It has been argued that the protein content of the ash is a reasonable surrogate measure of the degree of risk deduction caused by the incineration process. This assumption is questionable in view of the resistance to heat of prions as compared to other proteins. Protein measurements in ash are however probably a useful general measure of the overall efficiency and reproducibility of the incineration process. Results in the aforementioned report1 indicate a large degree of variability in performance among the small incinerators in the UK that have been evaluated. It is anticipated that small incinerators, used by other Member States will also show a considerable variation in performance. In evaluating the risk of small incinerators, consideration should be given to the risk of potential contamination of the ash and of the gaseous emissions. In the absence of generally accepted and enforced performance standards for small incinerators handling SRMs each such facility therefore needs to be the subject of a specific risk assessment. The SSC considers that the standards set up by the new Waste Incinerator Directive (2000/76/EC) and in its opinion of June 1999 on waste disposal should serve as guidance. In the absence of reliable data on the possible residual infectivity of the ash, it should be disposed of, i.e., in controlled landfills as described in the SSC opinion of June 1999 on safe disposal of waste. The SSC finally wishes to emphasise the need for suitable monitoring methods in order that risks can be assessed readily for individual types of small incinerators. 2 P.Brown, pers.comm., December 2002. Publication in progress.4
THE USE OF SMALL INCINERATORS FOR BSE RISK REDUCTION REPORT
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by Commission Services to (i) evaluate a risk assessment3 prepared for the UK's Spongiform Encephalopathy Advisory Committee (SEAC), on the potential risk arising from the use of small incinerators to dispose of specified risk materials and (ii) to advise on the safety with regard to TSE risks of the use of such small incinerators.
The SSC appointed Prof. J. Bridges as rapporteur. His report was discussed and amended by the TSE/BSE ad hoc Group at its meeting of 9 January 2003 and by the SSC at its meeting of 16-17 January 2003.
2. CURRENT LEGISLATIVE FRAMEWORK
Until 2000, small incinerators were exempt from the emission limits set by the EC for MSW and hazardous waste incinerators with throughputs greater than 50 kg/hour. An "incineration plant" is defined by the new Incineration of Waste Directive (2000/76/EC) as "any stationary or mobile technical equipment dedicated to the thermal treatment of waste with or without recovery of the combustion heat generated". This definition would appear to exclude open burning of waste. The new Directive, which must be transposed into the legislation of each Member State by December 2002, replaces a range of previous directives on incineration. It applies to all new incinerator installations from December 28th 2002 and all existing installations from December 28th 2005. The principal aim of the Directive is to prevent and/or limit negative environmental effects due to emissions into air, soil, surface and ground water and the resulting risks to human health from the incineration and co-incineration of waste. It covers many aspects from a requirement for afterburners to airborne emission limits and criteria for the composition of residual ash. Previous EC legislation has exempted small incinerators (i.e. those operating at less than 50 kg per hour). The Waste Incinerator Directive (WID) (2000) allows such small incinerators to be exempt from licensing at the national level however they will still be subjected to the same onerous requirements of the WID as larger incinerators.
In the UK it is proposed that in future incinerators dealing with non-hazardous waste but with a throughput of less than 1 tonne per hour will be regulated by local authorities whereas those with a larger throughput will be regulated by the national authority. It is possible that different regulatory mechanisms may result in differences in the rigour with which the new standards are enforced. The position on the disposal of animal waste is complicated. Animal carcass incineration use not covered by the WID and therefore the existing regulatory framework (90/66/EEC which covers animal and public health requirements to ensure destruction of pathogens) will continue to be applied. A new Animal By-Products Regulation
3 DNV Consulting (Det Norske Veritas), 2001. Risk assessment of SRM incinerators. Prepared for the UK Ministry of Agriculture, Fisheries and Food. Revision 2 of the Draft report, February 2001. 24 pages. 5
(ABPR) will apply in Member States during the first part of 2003. The relationship to WID has been included in the ABPR. It is important that it does not result in less strict standards being applied for animal carcass incineration. In contrast to whole carcasses WID will apply to the burning of meat and bone meal, tallow or other material (even if they burn animal carcasses too). Additional specific directives will continue to apply to waste that could be contaminated with BSE/TSEs. (96/449/EC)
3. CURRENT USE OF SMALL INCINERATORS TO DISPOSE OF ANIMAL WASTE Small incinerators are used for a variety of purposes and in a range of locations among Member States. Many are located alongside small abattoirs, knackers, hunt kennels, or laboratories. Thus they meet the needs of relatively small communities. Across Member States these small incinerators include a variety of designs and operating conditions (as indicated above in principle they will probably be required to meet specific standards for emissions and for the composition of the residual ash by December 28th 2005). In the UK there are indications (see DNV Report 2001) that a considerable quantity of SRM which would have previously been sent for rendering is now being incinerated directly in small incinerators. Thus evaluation of the risks from such incinerators is of increasing importance.
4. RISK ASSESSMENT FOR SMALL INCINERATORS
The SSC, at its meeting of 28th -29th June 2001, recommended "a framework for the assessment of the risk from different options for the safe disposal or use of meat and bone meal (MBM) and other products which might be contaminated with TSEs and other materials. This framework comprised five components:
(1) Identification and characterisation of the risk materials involved, the possible means for their transmission and potential at risk groups.
(2) The risk reduction achieved by the particular process.
(3) The degree to which the risks can be contained under both normal and emergency operating conditions. This inevitably includes consideration of the effectiveness of control measures.
(4) Identification of interdependent processes for example transport, storage, loading of any TSE related risk materials.
(5) The intended end-use of the products for example disposal, recycling etc. Recently a report has been prepared by DNV consulting (2001) for the UK Ministry of Agriculture, Fisheries and Food (now known as DEFRA) that assesses the risks from small incinerators in the UK that receive SRMs. This report focuses on the risks involved steps 1 and 2 in respect of BSE/TSEs only. 10 incinerators out of a total of 263 in the UK were visited of which 60% had after burners.
(1) Nature of the materials handled.
The DNV report 2001 starts with the assumption that "the materials incinerated at small abattoirs will be mainly SRM and bones from animals that are fit for human consumption. It may also include material from animals failed by meat inspectors. The likelihood of there being an animal 6 with significant BSE infectivity is very small and certainly much less than for the fallen stock handled by hunt kennels and knackers4. For this reason the study has concentrated on the latter type of operation". The Report notes that "the material handled by both knacker and hunt kennels is highly variable and difficult to characterise". In terms of input the key factors to consider are:
* The number of adult bovines processed and the proportion of these carcasses that are likely to be infected.
* The extent of infectivity (in terms of human oral Infectious Units) that may occur (average and worst case).
In the DNV (2001) risk assessment only the BSE risk from processing bovine SRMs was considered. For quantitative risk assessment purposes the mean value of the oral ID50 for cattle was taken as 0.1 gram. A range of values was taken to cover uncertainty in the inter-species barrier from 104 to 1 (as recommended by the SSC 2000). In order to assess the likelihood that a particular carcass could be infected, UK and Swiss monitoring data was used. An incidence rate based on Prionics test findings of between 0.013 and 0.0025 was calculated. The DNV Report notes that prevalence rates are progressively reducing from these 1998/99 figures. Finally the report concludes that the SRM from an infected bovine could contribute 700 Infectious Units.
(2) Risk reduction due to incineration
Once a carcass/SRM has been introduced into a small incinerator there are two main sources for the potential release of BSE infectivity
(a) Airborne emissions (b) Residual ash
There is no direct data on the TSE levels that may occur in those two media. The SSC however is aware of currently ongoing heat studies mimicking various incineration conditions and scenarios and aiming at assessing the TSE clearance efficacy of these processes (P.Brown, pers.comm., 16.01.03) on both the residual ash and the trapped emission gases. In the absence of final data from such experiments for individual (small) incinerator types, the DNV Report (2001) assumes that measurement of the total protein content of ash is a relevant surrogate for BSE/TSE material. Protein content is a useful indicator of the general performance of an incinerator. However it is much more problematic whether it is also a valid marker for possible BSE/TSE contamination as it known that BSE/TSE are relatively heat resistant as compared to other proteins. Failure to detect certain amino acids present in prions is encouraging but the sensitivity limits for amino acids are relatively poor for reassurance purposes. Equally important, the data provided in the DNV report shows moderate split sample 4 It may be mentioned that this assumption may be valid for the UK as a whole, but note necessarily for all other Member States. 7 variation but often substantial inter sampling variation (up to 600 fold). This indicates a wide span of performance standards among the small SRM incinerators in the UK and most likely across the whole of the EU. Typically performance was substantially poorer than is the case for larger incinerators. Unburned material is not uncommonly noted in the ash from small incinerators. If the reduction in protein content due to incineration is accepted as a valid indicator, typical infectivity reduction can be calculated to be of the order of 1600 (DNV Report 2001). Incinerators are known to emit particulate matter from their stacks. Larger incinerators have much higher stacks to facilitate disposal of emissions, they also have gas cleaning equipment to minimise the emission of particulate matter, metals and acidic gases. Small incinerators generally do not have any gas cleaning equipment. It can be speculated (as in the DNV Report 2001) that unburned materials (and therefore potentially infections is much less likely to be emitted in the form of particulate matter than burnt material. Nonetheless there is no data to support this assumption.
(3) Other considerations.
(a) Disposal of ash.
In the case of small incinerators ash is often dispersed of locally to a trench, which is typically neither lined, nor is the residue buried deeply. In contrast for larger incinerators in the UK ash is normally disposed of to a contained landfill. The risk from disposal to a trench is difficult to gauge in the absence of reliable data on the possible infectivity of the ash.
(b) Management factors.
Almost inevitably the level of expertise available for the management of small incinerators is highly variable because few such facilities can afford to employ specialists in incineration. This is also likely to be often the case for the inspectors as well. While such considerations cannot formally be taken into account in a risk assessment, they are not the less relevant factors that need to be considered in assessing the risk from a particular plant.
The DNV 2001 risk assessment relies greatly on the assumption that BSE/TSE contaminated material is very unlikely to be processed. The Report seeks to compare the risks from a small incinerator with that from large SRM incinerators which the author had assessed previously (DNV, 1997). It identifies that the risk is four-five -fold less from a typical small incinerator because the scale of activities is much lower. However it is noted that the amount of experimental data to back this conclusion is extremely limited and does not take into account either risks from the residual ash or any consequences of a substantially lower stack height limiting the dilution of the emitted particulate and gaseous matter. 8
5. FURTHER INVESTIGATIONS
In view of the uncertainty regarding the risks due to BSE/TSE contamination of the fly and bottom ash and airborne emissions it is recommended that further research is conducted to identify the residual risks (along with attendant uncertainties) from the burial of ash (without further treatment,) in uncontained sites. It is essential that suitable monitoring methods are developed.
EC (European Commission), 1999. Opinion on The risks of non conventional transmissible agents, conventional infectious agents or other hazards such as toxic substances entering the human 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. Adopted By the Scientific Steering Committee at its meeting of 24-25 June 1999 and re-edited at its meeting of 22-23 July 1999. DNV Consulting (Det Norske Veritas), 1997. Risks from disposing of BSE infected cattle in animal carcass incinerators. Report prepared for the UK Environment Agency. DNV Consulting (Det Norske Veritas), 2001. Risk assessment of SRM incinerators. Prepared for the UK Ministry of Agriculture, Fisheries and Food. Revision 2 of the Draft report, February 2001. 24 pages. SEAC (Spongiform Encephalopathy Advisory Committee, UK), 2001. Public summary of the SEAC meeting of 25 April 2001.
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Terry S. Singeltary Sr. P.O. Box 42 Bacliff, Texas USA 77518
-------- Original Message --------
Subject: Infectivity Studies of Both Ash and Air Emissions from Simulated Incineration of Scrapie-Contaminated Tissues [FULL TEXT]
Date: Wed, 29 Dec 2004 12:47:54 -0600
From: "Terry S. Singeltary Sr." Reply-To: Bovine Spongiform Encephalopathy
##################### Bovine Spongiform Encephalopathy #####################
Infectivity Studies of Both Ash and Air Emissions from Simulated Incineration of Scrapie- Contaminated Tissues
P A U L B R O W N , * , E D W A R D H . R A U , ! P A U L L E M I E U X , § B R U C E K . J O H N S O N , A L F R E D E . B A C O T E , A N D D . C A R L E T O N G A J D U S E K |
Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, and Division of Environmental Protection, Office of Research Facilities Development and Operations, National Institutes of Health, United States Department of Health and Human Services, Bethesda, Maryland 20892, National Homeland Security Research Center, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, and Institut Alfred Fessard, Centre National de la Recherche Scientifique, 91198 Gif sur Yvette, France
We investigated the effectiveness of 15 min exposures to 600 and 1000 °C in continuous flow normal and starvedair incineration-like conditions to inactivate samples of pooled brain macerates from hamsters infected with the 263K strain of hamster-adapted scrapie with an infectivity titer in excess of 109 mean lethal doses (LD50) per g. Bioassays of the ash, outflow tubing residues, and vented emissions from heating 1 g of tissue samples yielded a total of two transmissions among 21 inoculated animals from the ash of a single specimen burned in normal air at 600 °C. No other ash, residue, or emission from samples heated at either 600 or 1000 °C, under either normal or starved-air conditions, transmitted disease. We conclude that at temperatures approaching 1000 °C under the air conditions and combustion times used in these experiments, contaminated tissues can be completely inactivated, with no release of infectivity into the environment from emissions. The extent to which this result can be realized in actual incinerators and other combustion devices will depend on equipment design and operating conditions during the heating process.
Safe disposal of medical wastes, carcasses of cattle with bovine spongiform encephalopathy (BSE), cervids with chronic wasting disease (CWD), sheep with scrapie, and more generally, anyhumanor animal tissue infected or potentially infected with one of the agents that cause transmissible spongiform encephalopathy (TSE) continues to be an issue of concern. High temperature incineration has been the method of choice for treatment of medical and veterinary wastes by virtue of its proven ability to inactivate all types of conventional pathogens, high throughput capacity, and significant volume reduction. However, TSE agents are uniquely resistant to most physical and chemical methods of disinfection, including dry heat (1-3).
In a previous series of experiments (4), we showed that transmission could occur even after ashing infected tissue in a covered crucible at 600 °C: the ash from one sample of fresh brain tissue heated for 15 min transmitted to five of 18 animals (another sample heated for 5 min did not transmit to any of the 15 animals), and one formalin-fixed sample heated for 5 min transmitted to one of 24 animals. As no transmissions occurred from any sample heated to 1000 °C, the infectivity extinction point was somewhere between 600 and 1000 °C, most probably very close to 600 °C, approaching the operating temperature of some incineration units. Because of concerns about the reproducibility of these unprecedented results, and about the possibility that some infectivity might be entrained in stack gases vented during incineration, we designed an experimental apparatus to produce conditions that reflect more closely actual incineration conditions, in which gases flowed across a heated open crucible containing contaminated tissue, oxidizing or pyrolyzing the tissue, and partially entraining some of the ash; wealso performed infectivity bioassay measurements of both ash and emissions. The 263K strain of hamster-adapted scrapie was chosen because the concentration of infectivity in brain tissue of terminally ill animals is as high or higher than in any other TSE, natural or experimental, and thus allows the maximum measure of reduction, and because this strain shows resistance to heat that is comparable to that of BSE and superior to other tested TSE strains (refs 5-8 and personal communication from Dr. David Taylor, Edinburgh, Scotland).
We here report that once again, despite the nearly total destruction of over 109 LD50, and individual bioassay animal caging to avoid any possibility of cross-contamination, an ashed sample of scrapie-infected tissue transmitted disease after having been exposed to 600 °C for 15 min, and once again, we found no survival after exposure to 1000 °C. We also show that no infectivity escaped into air emissions from 15 min test burns at either 600 or 1000 °C.
Whatever the mechanism of this minimal level of survival in extreme heatswhether a result of incomplete combustion, the existence of a mineralized template for replication, or some other unimagined phenomenonsit may be concluded that the exposure under carefully controlled laboratory conditions of a small sample of contaminated tissue to 1000 °C, under either an oxidizing or reducing atmosphere, will ensure complete sterilization of the ash and emissions. Exposure at 600 °C allows a minimal level of infectivity to persist in the ash but generates air emission products that are noninfective.
Tissue Samples. Brains from 20 terminally ill hamsters infected with the 263K strain of hamster-adapted scrapie were pooled, homogenized, and distributed into 1 g aliquots. The same procedure was used for a small pool of uninfected control brains. Samples were frozen until the test burns were initiated.
Simulated Incineration. The incineration simulation apparatus was constructed, and test burns were performed at the U.S. Environmental Protection Agency s National Risk * Corresponding author phone: (301)652.5940; fax: (301)652-4312; e-mail: email@example.com.
Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health. ! Division of Environmental Protection, National Institutes of Health.
§ National Homeland Security Research Center. | Centre National de la Recherche Scientifique. Environ. Sci. Technol.2004, 38,6155-6160 10.1021/es040301z CCC: $27.50 ã 2004 American Chemical Society VOL. 38, NO. 22, 2004 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 6155 Published on Web 10/19/2004
Management Research Laboratory located at Research Triangle Park, NC. Tissue samples were heated in a 2.54 cm (1 in.) diameter quartz reactor (Prism Research Glass, Research Triangle Park, NC) placed inside a Lindberg furnace (Blue M Model 542 32-V). Three separate, nearly identical quartz reactors were used. One reactor was only used for the 1000 °C tests, and the other two were alternated for the 600 °C tests. Gas flow through the experimental system was controlled with a rotameter (Gilmont Instruments, a Barnant Company, Barrington, IL).
A two-stage impinger was used to collect emissions from the gas stream exiting the reactor: the first stage discharged the gas through deionized water in a tube held in an ice bath; gas exhausted from the first impinger trap flowed into a second trap suspended in dry ice within a polystyrene foam container. The apparatus is shown schematically in Figure 1 and is photographed in Figure 2. All components of the impinger system were made of quartz glass and connected with Teflon couplings. Metal components were avoided because of their tendency to bind amyloid protein (9). The entire apparatus was located in a fume hood.
The experimental matrix included testing of normal and infected tissues at both 600 and 1000 °C. Experiments were performed under oxidative (combustion) and reducing FIGURE 1. Schematic view of incineration simulation apparatus showing, from left to right, the gas inlet, Lindberg furnace surrounding a removable combustion chamber (quartz reactor tube), quartz exhaust tube, emission impingers (ice water bath followed by dry ice bath), and exhaust through filter into fume hood.
FIGURE 2. Photograph of the incineration simulation apparatus. 6156 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 38, NO. 22, 2004 (pyrolytic) conditions: oxidative conditions utilized humidified air, and reducing conditions utilized humidified nitrogen (N2) as the reactor inlet gas. These parameters were selected to simulate conditions within incinerators commonly used for destruction of medical waste.
Before each test, the reactor was immersed for 30 min in a 1:1 aqueous solution of freshly prepared sodium hypochlorite (Clorox bleach) and then extensively rinsed with deionized water and allowed to dry. The clean, dry reactor was then placed into the Lindberg furnace, and the furnace temperature controls were adjusted to the desired setting based on calibrations that were performed prior to the experiments. Each 1 g tissue sample was thawed and placed into anewquartz crucible. Before beginning the experiments, a type-K thermocouple (Omega, Model No. KQXL-18G-12) was used to measure the gas temperature at the axial location of the reactor where the crucible would be inserted. The temperature was allowed to equilibrate until no significant temperature change occurred. The furnace temperature was then logged, and the thermocouple was removed. After removal of the thermocouple, the impinger train (Prism Research Glass, Research Triangle Park, NC) was installed onto the outlet of the reactor, the inlet gas system was connected to the reactor, and the temperature of the impinger train was logged. A bubble meter was used to perform a leak check by setting the gas rotameter to the desired flow rate and checking the impinger train outlet flow rate. After the leakage rate was determined for each test and airflow was found to be within the acceptable range (50-70 mL/min), the tissue sample contained in the quartz crucible was placed into the crucible holder and inserted into the reactor, and a clip was placed around the joint between the reactor and the crucible holder. All samples were heated for 15 min.
Collection and Processing of Ash and Emission Samples. At the end of each test burn, the clip holding the crucible holder to the reactor was removed, and the crucible holder with crucible inside was removed and immediately cooled. The crucible with its contained ash was then placed in a labeled sample vial. It was noted that the reactor walls and crucible were coated with opaque, glasslike surface deposits after the 1000 °C tests. When found in the reactor, these deposits were dislodged using a stainless steel spatula, collected from the reactor as thoroughly as possible, and placed in the labeled sample vial along with the ash from each crucible. The collected ash and deposits were then transferred to a Tenbroeck tissue grinder and homogenized in 1 mL of distilled water.
Following each test burn, the impinger train was removed, labeled, and sealed. The entire impinger train was placed at 4 °Cfor storage and later transported to the National Institutes of Health in Bethesda, Maryland for bioassay of the impinged emission materials that were recovered separately from the glass tubing leading from the burner to the first impinger and from the traps. Visible deposits from the tubing were assiduously scraped, rinsed into a tissue grinder, and homogenized in 1mL of distilled water. Water from the first trap was allowed to evaporate inside a laminar flow hood to a volume of approximately 1 mL, which was transferred together with all associated tube residues from both traps to a tissue grinder and homogenized. Each test burn yielded three samples: (1) residue collected from the crucible and deposits from the inside of the heated zone of the reactor (ash); (2) residue from the exhaust zone of the reactor tube to the first impinger trap (exit tube residue); and (3) commingled water and residues from the two impinger traps (air emission samples).
Bioassays. The total volume of each sample was inoculated undiluted into groups of healthy female weanling hamsters (0.05 mL per animal by the intracerebral route; approximately 20 animals per sample). Twenty uninoculated sentinel animals were randomly positioned among the inoculated bioassay animals, all of which were individually caged, to avoid fighting and any possibility of crosscontamination. Animals were observed for a period of 12 months for clinical signs of scrapie, at which point the survivors were euthanized. The brains of all animals, whether dying during the observation period, or surviving to its conclusion, were examined for the presence of proteinaseresistant protein (PrPres) by Western blot immunoassays.
The 12 month observation period was mandated by considerations of cost and space associated with prolonged care of the largenumberof animals ( 450) needed to conduct this study. The occurrence of rare transmissions after longer incubation periods in rodents inoculated intracerebrally with low dose infectious material has been documented (10, 11), but this possibility was mitigated in our experiment by the examination of all brains for the presence of PrPres, which is visible well before the onset of symptomatic disease (12, 13).
Western BlotImmunoassays. Approximately 0.1 gof brain tissue was extracted per sample by the phosphotungstic acid method described by Safar et al. (14) and blotted using the monoclonal anti-hamster PrP antibody 3F4 at a dilution of 1:2000. Samples giving a questionable positive result were reextracted using the purification/concentration method of Xi et al. (15): all six such samples were found to be clearly negative on retesting.
Results and Discussion
Bioassay results for each tested sample are summarized in Table 1. It is important to note that the all material recovered from each test burnsapproximately 1 mL volumes of resuspended ash, residues, or emissionsswas inoculated to avoid any sampling error that can be significantwhendealing with very low levels of infectivity.
Two unheated 263K brain tissue samples were assayed, yielding levels of infectivity of 109.2 and 109.7 LD50/g of tissue macerate. Incubation periods in the lowest dilution (10-1) groups were between 50 and 60 days; incubation periods in the highest positive dilution groups (titration end point) ranged from 120 to 180 days.
The residual ash from the 1 g sample of 263K brain macerate heated at 600 °C in normal air transmitted disease to two of 21 inoculated animals after incubation periods of 261 and 303 days, and their brains were positive for PrPres. The clinical signs and PrPres patterns in both hamsters were TABLE 1. Bioassay Results for Combustion Products from Heated Infected Hamster Brain Tissue Macerates and Controlsa test conditions bioassay specimen tissue gas °C crucible exit tube traps
normal air ambient NA NA NA
normal air 600 0/20 NT NT
normal N2 603 0/21 0/18
normal air 1015 0/23 NT NT
normal N2 1000 0/20 0/18
infected air ambient NA NA NA
infected air 612 2/21 0/22 0/24
infected N2 598 0/20 0/19 0/26
infected air 996 0/15 0/26 0/23
infected N2 997 0/23 0/18 0/23
a For each test group, fractions represent number of PrPres-positive animals over total number of inoculated animals. Residues from the exit tubes and emissions from the impinger traps were combined for bioassays of the uninfected control samples subjected to 600 and 1000 °C under N2. NA ) not applicable; NT ) not tested.
VOL. 38, NO. 22, 2004 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 6157 indistinguishable from those of the positive control animals that received unheated inocula.
No other heated samples were infectious, based on the absence of symptomatic disease and brain PrPres, including reactor exit tube residues and emission samples from tissues heated to 600 °C; ash, exit tube residues, and emissions from tissues heated to 1000 °C; and normal brain tissue heated to 600 °C (bioassays were not done on normal tissue heated to 1000 °C). In particular, no clinically healthy animal surviving to the observation end point was found to have PrPres in the brain (i.e., no preclinical or subclinical infections were detected 12 months after inoculation). All uninoculated sentinel animals also remained asymptomatic and PrPresnegative. Comparison of Experimental and Actual Incineration Conditions. The question as to whether medical waste incinerators and other types of combustion units used for disposal of contaminated materials provide the conditions necessary for inactivation of TSE cannot be completely answered by laboratory experimentation. It is acknowledged that experiments such as these cannot duplicate the dynamic operating conditions and complex rheology of incinerators and the myriad of interactions with other waste constituents that occur in a combustion environment. However, smallscale simulations can provide valuable qualitative information regarding the behavior of materials in a high temperature combustion environment under tightly controlled conditions. With this limitation in mind, we offer the following comparisons of our experimental conditions with those expected in actual incinerators and comment on the implications of our data for potential environmental releases of infectivity from combustion processes.
Types of Incinerators and Operating Temperatures. In the U.S., three types of incinerators are typically used for disposal of medical wastes: controlled-air two-stage modular systems, excess air batch systems, and rotary kilns (16, 17). Of these, the controlled-air (also referred to as starved-air) systems are the most widely used today (18). In these units, combustion of wastes occurs in two stages. In the first stage, waste is fed into the primary chamber, which is operated with less than the stoichiometric amount of air required for combustion. Air enters from both above and below the burning bed of waste, which is dried, volatilized, pyrolized, and partially combusted. In this chamber, the air temperature above the waste is typically 760-980 °C. In the second stage, air is added to the gases produced in the first chamber to complete combustion, and the gas temperature is higher, typically 980-1095 °C. The partial combustion of the waste in the first stage yields a gas with sufficient heating value to operate the combustion process in the second stage without the need for additional fuel. Gas temperatures in each chamber of controlled-air incinerators are thus higher than the temperatures observed in our experiments to achieve, respectively, near-total and total inactivation of the agent. Excess air medical waste incinerators are typically small modular units, usually designed with two chambers and provisions for manual loading of waste into the primary chamber and removal of ash. Burners are ignited to bring the secondary chamber to an operating temperature of 870- 980 °C. When this temperature is reached, the burner in the primary chamber is ignited. The unit is operated with levels of air that are approximately 100% higher than the stoichiometric amount of air required for combustion.
The operating temperatures of modern medical waste incinerators, which typically operate well above 600 °C, should reduce TSE infectivity concentrations to levels at or very close to extinction. However, it should be noted that these temperatures are usually measured in the gases above the bed of burning waste, not in the bed itself. Themaximum temperatures achieved in the bed may be as much as 100 °C lower than the gases, depending on the bed depth, composition of the input material, and other factors. Accordingly, incinerators used to dispose of TSEs should not be operated at lower temperatures. Indeed, studies by theEPAhaveshown that incinerators operated at air temperatures of about 600 °C may not even inactivate conventional pathogens that are much less resistant to thermal inactivation than TSEcontaminated materials (35).
Large-volume, nonmedical waste streams that may contain TSE-contaminated livestock and wildlife carcasses or meat and bone meal(MBM)have been disposed of by various methods. In the U.K., all carcasses are incinerated in dual chamber facilities with primary and secondary chamber temperatures of approximately 850 and 1000 °C, respectively. These incinerators typically operate at a carcass input batch rate ranging between 100 and 1000 kg/h (average 450 kg/h), with a solid-phase residence time of 1 h (personal communication, Dr. Stephen Wyllie, Department for Environment, Food and Rural Affairs, U.K.). MBM may also be incinerated, may be subjected to other thermal technologies including rotary kilns, fluidized beds, and cement plants, or co-fired in power plants with fuels such as coal, lignite, and other wastes (19). If these nonincineration systems operate under conditions similar to incinerators, they may be expected to provide a similar level of inactivation. Evaluations by the German Federal Institute for Viral Illnesses in Animals and the Institute for Biological Safety indicate that the incinerators used inGermanyfor disposal ofMBNcan achieve a temperature of 600 °C for 15 min in the waste if specific operating conditions are met (20, 21). Incinerators used in the U.S. for disposal of municipal waste operate at temperatures above 1000 °C (22).
Concentration of the Infectious Agent. In these experiments, the waste load consisted of pure brain tissue with an extremely high concentration of infectivity (>109LD50/g). In actual incinerators, the concentration of infectivity in the waste load will be much lower than that in our experiments because the brain infectivity concentration in hamsters infected with the 263K strain of scrapie is at least 2-3 logs higher than in livestock infected with either BSE or scrapie (CWD brain has not been titered) and also because high infectivity central nervous system tissues are diluted in the mix of peripheral carcass (orMBM)tissues that contain little or no infectivity.
In medical waste incinerators, mixing of TSE tissues and contaminated items with other materials also dilutes the concentration of the agent in the waste load. Tissues usually comprise only a small percentage of the total volume of most hospital waste streams; almost all of the mass of material that is classified as medical waste is comprised of noninfectious materials such as paper and plastic (23); and medical wastes are often burned together with noninfectious, nonmedical waste.
Dilution of the infectious agent in a much larger volume of noninfectious material is theoretically advantageous because it reduces the probability of the agent being in localized areas of the incinerator, which may have less than optimal conditions for inactivation. An example of such an area is the zone near the incinerator walls, which may be cooler than the rest of the chamber. Conversely, mixing TSE contaminated materials with other wastes could adversely impact inactivation by insulating the agent and decreasing its total time of exposure to inactivation temperatures. Combustion Gases. In some of these experiments, pure nitrogen gas was used to simulate the combustion gas in the primary chamber of a controlled-air incinerator. Oxygen in the small volume of air that entered the reactor during the few seconds when the crucible holding the tissue sample was inserted would have been rapidly purged from the system, probably before the sample was dried out and heated
6158 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 38, NO. 22, 2004
to the target temperature. Thus, virtually all of the test burns using nitrogen were carried out under anoxic conditions. This differs somewhat from actual starved-air incineration conditions where limited amounts of air enter the chamber throughout the combustion cycle, and partial oxidation of waste constituents occurs. Volatilized organic and particulate materials from the primary chamber enter the secondary chamber where excess air is added to complete oxidization of these materials.
The ash from controlled-air incinerators has a relatively high carbon content, typically from 3 to 6% and values as high as 30% are common (17). The high carbon content is of concern because there is some evidence (24) that the presence of carbon may protect TSE infectivity, and some of the residues observed in the reactor exit tube and impinger traps in these experiments were similar in color and form to carbon black.
Although the nitrogen used as a reactor carrier gas did not contain any oxygen, as would be present in actual controlled-air incinerators, the results yielded information relevant to inactivation mechanisms at higher temperatures. No transmissions were detected in ash or emissions from infected issues in the test burns performed in nitrogen, confirming that the presence of oxygen is not required to inactivate the agent and that any carbon formed was not sufficiently protective to prevent its inactivation. The lack of transmission from test burns in anoxic conditions also suggests that denaturation or some inactivation mechanism other than chemical oxidation may be operative at incineration temperatures. These results may have potential application in selection of waste processing technologies, particularly for high-volume waste streams such as MBM and animal carcasses. High-temperature, anoxic waste pyrolysis systems that can yield biofuels and other useful byproducts could be considered as alternatives for incineration, which is usually a strictly destructive process.
SecondaryChamber.Another aspect of these experiments that differed from actual incineration conditions was that the vented gases from the reactor tube, which is functionally similar to the primary chamber of an incinerator, were exhausted directly into a cold impinger train. In actual incinerators, the vented emissions from the primary chamber typically enter a secondary chamber, which is usually operated at a temperature higher than the primary chamber, providing additional opportunity for the inactivation of any pathogens carried in the gas phase. Depending on the system design, gases exiting the secondary chamber may then be cooled and passed through scrubbers or other types of air pollution control equipment before they are released to the environment. In our experiments, no infectivity was detected in emission deposits collected directly from the exhaust end of the reactor tube. This suggests that the agent would be inactivated or retained in the ash in the first chamber of an incinerator and that the potential for contamination of residues, wastewater, and other effluents generated by gas cooling and air pollution control systems is minimal.
Any thermal treatment process whether incineration or alternative technologys that ensures exposure of TSE wastes to temperatures of 1000 °C for at least 15 min should result in sterile output products, as the minimum temperature required to achieve sterility is probably only marginally above 600 °C. Treatment at 600 °C may thus produce an ash that is either sterile or contains a level of residual infectivity well within regulatory requirements for reductions of conventional pathogens in sterile products. In our experiments, over one billion LD50 of scrapie infectivity were reduced to less than a single LD50 (two transmissions among 21 inoculated animals) by a 15 min exposure to dry heat at 600 °C. Although it may be objected that even this degree of reduction does not achieve zero risk, it is approximately 10-fold greater than the most stringent process validation guidelines issued by the FDA to ensure the safety of biological products (up to 8 log virus removal) (25) or than the standard used by the EPA for registration of sterilants (no growth of Bacillis subtilis in 720 carriers each having at least 2 105 spore counts) (26). For TSE inactivation conditions to be met, incinerators and other thermal treatment systems must be properly selected and operated. In actual incinerators, inactivation conditions can be adversely affected byanarray of operational factors, such as overloading, cold start-ups and shut-downs, inadequate control of air flow, insufficient or excessive turbulence, and loss of partially burned material through grates. Under these failure mode conditions, inactivation may be incomplete.'
Given a hypothetical potential for survival of trace amounts of TSE infectivity in the combustion products of incinerators operated under suboptimal conditions, the likelihood of disease transmission via environmental media is minimized by several factors including the following: dilution; hydrophobic properties of agents that would be expected to reduce their mobility in water and soils; containment provided by ash landfill design and operations; biological degradation; species barriers; and the inefficiency of likely routes of exposure (27-32). It should also be noted that neither humans nor animals appear to be susceptible to air-borne TSE infections, further diminishing any potential risk from incinerator emissions.
Prior to this study, data on inactivation of TSE-infected tissues in incinerator emissions were not available for risk assessment, and probabilistic approaches were used to assess the risks of combustion processes, including the burning of carcasses in open pyres. These approaches led to conclusions that the risk of transmission to humans was extremely low (33, 34). Our study provides actual data on inactivation under incineration conditions and offers further reassurance that TSE materials can be safely disposed of via incineration.
The authors thank Mr. David Liles of ARCADIS G&M, who set up and operated the reactor and impinger train, and Mr. George Nelson, who conscientiously scraped all tubing and traps for emission residues. The combustion test portion of this work was performed under Interagency Agreement RW75938614 between the National Institutes of Health and the U.S. Environmental Protection Agency. Literature Cited (1) Brown, P.; Liberski, P. P.; Wolff, A.; Gajdusek, D. C. J. Infect. Dis. 1990, 161, 467. (2) Taylor, D. M.; Fraser, H.; McConnell, I.; Brown, D. A.; Brown, K. L.; Lamza, K. A.; Smith, G. R. A. Arch. Virol. 1994, 139, 313. (3) Taylor, D. M. Vet. J. 2000, 159, 10. (4) Brown, P.; Rau, E. H.; Johnson, B. K.; Bacote, A. E.; Gibbs, C. J., Jr.; Gajdusek, D. C. Proc. Soc. Natl. Acad. Sci. U.S.A. 2000, 97, 3418. (5) Kimberlin, R. H.; Walker, C. A.; Millson, G. C.; Taylor, D. M.; Robertson, P. A.; Tomlinson, A. H.; Dickinson, A. G. J. Neurol. Sci. 1983, 59, 335. (6) Schreuder, B. E.; Geertsma, R. E.; van Keulen, L. J.; van Asten, J. A.; Enthoven, P.; Oberthur, R. C.; de Koeijer, A. A.; Osterhaus, A. D. Vet. Rec. 1998, 142, 474. (7) Somerville, R. A.; Oberthur, R. C.; Havekost, U.; MacDonald, F.; Taylor, D. M.; Dickinson, A. G. J. Biol. Chem. 2002, 277, 11084. (8) Taylor, D. M.; Fernie, K.; Steele, P. J.; McConnell, I.; Somerville, R. A. S. J. Gen. Virol. 2002, 83, 3199. (9) Flechsig, E.; Hegyi, I.; Enari, M.; Schwarz, P.; Collinge, J.; Weissmann, C. Mol. Med. 2001, 7, 679. (10) Brown, P.; Rohwer, R. G.; Gajdusek, D. C. J. Infect. Dis. 1986, 153, 1145-1148. (11) Taylor, D. M. Brit. Med. Bull. 1993, 49, 810. VOL. 38, NO. 22, 2004 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 6159 (12) Jendroska, K.; Heinzel, F. P.; Torchia, M.; Stowring, L.; Kretzschmar, H. A.; Kon, A.; Stern, A.; Prusiner, S. B.; DeArmond, S. J. Neurology 1991, 41, 1482. (13) Muramoto, T.; Kitamoto, T.; Tateishi, J.; Goto, I. Am. J. Pathol. 1992, 140, 1411. (14) Safar, J.; Wille, H.; Itri, V.; Groth, D.; Serban, H.; Torchia, M.; Cohen, F.; Prusiner, S. Nature Med. 1998, 4, 1157. (15) Xi, Y. G.; Cardone, F.; Pocchiari, M. J. Neurol. Sci. 1994, 124, 171. (16) U.S. E.P.A. Medical waste incineration. Section 2.3 in Emission Factor Documentation for AP-42, 5th ed.; U.S. Environmental Protection Agency: Research Triangle Park, NC, 1993. (17) Seeker, R. W. Environmental Management in Health Care Facilities; Wagner, K. D., Ed.; W. B. Saunders: Philadelphia, 1998; pp 41-56. (18) National Research Council. Waste Incineration and Public Health. Committee on Health Effects of Waste Incineration. Board on Environmental Studies and Toxicology, Commission on Life Sciences; National Academy Press: Washington, DC, 2000. (19) Rodehutscord, M.; Abel, H.; Friedt, W.; Wenk, C.; Flachowsky, G.; Ahlgrimm, J.; Johnke, B.; Ku¨ hl, R.; Breves, G. Arch. Tierernahrung. 2002, 56, 67. (20) ISB Institut fu¨r Sicherheit in der Biotechnologie. Brief declaration on the incineration of MBM in Bavarian waste incineration plants, January 2001, ISB Institut fu¨r Sicherheit in der Biotechnologie/ TU¨ VSu¨ddeutschland, for the Bavarian Ministry for Rural Development and Environment, 2001. (21) Nottrodt, A.; Wandschneider, J.; Gutjahr, M.; Chibiorz, J. Technical Requirements and General Recommendations for the Disposal of Meat and Bone Meal and Tallow; Report Commissioned by the Federal Ministry for the Environment, Nature Protection and Reactor Safety, Berlin, 2001. (22) U.S. E.P.A. National Incinerator Testing and Evaluation Program: The Environmental Characterization of Refuse-derived Fuel (RDF) Combustion Technology, EPA-600/R-94-140, December, 1994. (23) Committee on Health Effects of Waste Incineration, National Research Council. Waste Incineration and Public Health; National Academy Press: Washington, DC, 2000. (24) Taylor, D. M. Vet. Micro. 1991, 27, 403. (25) Points to Consider in the Manufacture and Testing of Monoclonal Antibody Products for Human Use; U.S. Department of Health and Human Welfare, Food and Drug Administration, Center for Biologics Evaluation and Research, February 28, 1997; Table 3, p 27; (http://www.fda.gov/cber/gdlns/ptc_mab.pdf). (26) E.P.A. Supplemental Efficacy: Sterilizers. Test Requirements. DIS/ TSS-9; Efficacy Data Requirements (http://www.epa.gov/ oppad001/dis_tss_docs/dis-09.htm). Test Guidelines; MB-15- 00: AOAC Sporicidal Activity Test (Bacillus species), 2003; p 11; 10.7.10 (http://www.epa.gov/oppbead1/ methods/atmpa2z.htm). (27) Brown, P.; Gajdusek, D. C. Lancet 1991, 337, 269. (28) Bennett, A. D.; Birkett C. R.; Bostock C. J. Rev. Sci. Technol. 1992, 11, 569-603. (29) Gale, P. Lett. Appl. Micro. 1998, 27, 239. (30) Gale, P.; Young, C.; Stanfield, G.; Oakes, D. J. Appl. Micro. 1998, 84, 467. (31) Gale, P.; Stanfield G. J. Appl. Micro. 2001, 91, 563. (32) Weissman, C.; Enari, M.; Klohn, P. C.; Rossi, D.; Flechsig, E. Proc. Natl. Acad. Sci. U.S.A. 2002, 99 (Suppl. 4), 16378. (33) Cummins, E. J.; Grace P. M.; Fry, D. J.; McDonnell, K. P.; Colgan, S. F.; Ward, S. M. J. Agric. Safety Health 2002, 8, 365. (34) Comer, P. J.; Huntly, P. J. Stat. Methods Med. Res. 2003, 12, 279. (35) England, G. C.; Newhall J.; Barton, R.; Seeker, W. R. (1991) Characterization of Emissions from Hospital Incinerators; Proceedings of the 1991 Incineration Conference, University of California, Irvine, 1991. England, G. C.; Newhall J.; Barton, R.; Seeker, W. R. (1992) Characterization of Emissions from Hospital Incinerators; 85th Annual Meeting of the Air and Waste Management Association, Kansas City, MO, paper 92-40.03. Received for review January 2, 2004. Accepted June 14, 2004. ES040301Z 6160 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 38, NO. 22, 2004TSS
######### https://listserv.kaliv.uni-karlsruhe.de/warc/bse-l.html ##########
REPORT ON BOVINE CARCASS INCINERATION
a. after burning to the range of 800 to 1000*C to eliminate smell;
well heck, this is just typical public relations fear factor control. do you actually think they would spend the extra costs for fuel, for such extreme heat, just to eliminate smell, when they spread manure all over your veg's. i think not. what they really meant were any _TSE agents_.
b. Gas scrubbing to eliminate smoke -- though steam may be omitted;
c. Stacks to be fitted with grit arreaters;
1.2 Visual Imact
It is considered that the requirement for any carcase incinerator disign would be to ensure that the operations relating to the reception, storage and decepitation of diseased carcasses must not be publicly visible and that any part of a carcase could not be removed or interfered with by animals or birds.
this next one should work ;
Summary of Conclusions on the Vulnerability of Groundwater toContamination by BSE Prions at Thruxted Mill.
11. The summary
see more here ;
Tue, 8, Aug 2000 19:39:27 -0400
From: jonathan leake
Date: Tue, 8, Aug 2000 19:39:27 -0400
Subject: IN CONFIDENCE (I SMELL A STORY ......)
Sender: jonathan leake
To: BSE Terry Singletary
Message-ID: <200008081939_mc2-af13-1bc compuserve.com=""> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by sys44.hou.wt.net id SAA15659 X-Mozilla-Status: 8007 X-Mozilla-Status2: 00000000 X-UIDL: ed0acd360d74370a3e06000000000000200008081939_mc2-af13-1bc>
Hi Terry - this is Jonathan Leake here.
we're thinking of doing a story on the knackers yard meat issue - is there a link to Queniborough?
Would you mind resending any info you have on this - I may have lost some of the stuff you sent.
Cd you send it to
- HE'S RESEARCHING THIS STORY FOR ME AS I'M AT A CONFERENCE
MANY THANKS FOR YOUR HELP - AND FOR ALL THE GOOD WORK YOU'VE BEEN DOING
*** The potential impact of prion diseases on human health was greatly magnified by the recognition that interspecies transfer of BSE to humans by beef ingestion resulted in vCJD. While changes in animal feed constituents and slaughter practices appear to have curtailed vCJD, there is concern that CWD of free-ranging deer and elk in the U.S. might also cross the species barrier. Thus, consuming venison could be a source of human prion disease. Whether BSE and CWD represent interspecies scrapie transfer or are newly arisen prion diseases is unknown. Therefore, the possibility of transmission of prion disease through other food animals cannot be ruled out. There is evidence that vCJD can be transmitted through blood transfusion. There is likely a pool of unknown size of asymptomatic individuals infected with vCJD, and there may be asymptomatic individuals infected with the CWD equivalent. These circumstances represent a potential threat to blood, blood products, and plasma supplies.
Monday, June 24, 2013
The Effects of Chronic Wasting Disease on the Pennsylvania Cervid Industry Following its Discovery
Thursday, June 20, 2013
atypical, BSE, CWD, Scrapie, Captive Farmed shooting pens (livestock), Wild Cervids, Rectal Mucosa Biopsy 2012 USAHA Proceedings, and CJD TSE prion Update
Wednesday, May 15, 2013
Intranasal Inoculation of White-Tailed Deer (Odocoileus virginianus) with Lyophilized Chronic Wasting Disease Prion Particulate Complexed to Montmorillonite Clay
Friday, February 08, 2013
*** Behavior of Prions in the Environment: Implications for Prion Biology
Friday, November 09, 2012
*** Chronic Wasting Disease CWD in cervidae and transmission to other species
Sunday, November 11, 2012
*** Susceptibilities of Nonhuman Primates to Chronic Wasting Disease November 2012
Friday, December 14, 2012
Susceptibility Chronic Wasting Disease (CWD) in wild cervids to Humans 2005 – December 14, 2012
Tuesday, April 16, 2013
Cervid Industry Unites To Set Direction for CWD Reform and seem to ignore their ignorance and denial in their role in spreading Chronic Wasting Disease
pens, pens, PENS ???
*** Spraker suggested an interesting explanation for the occurrence of CWD. The deer pens at the Foot Hills Campus were built some 30-40 years ago by a Dr. Bob Davis. At or abut that time, allegedly, some scrapie work was conducted at this site. When deer were introduced to the pens they occupied ground that had previously been occupied by sheep.
now, decades later ;
PO-039: A comparison of scrapie and chronic wasting disease in white-tailed deer
After a natural route of exposure, 100% of WTD were susceptible to scrapie. Deer developed clinical signs of wasting and mental depression and were necropsied from 28 to 33 months PI. Tissues from these deer were positive for PrPSc by IHC and WB. Similar to IC inoculated deer, samples from these deer exhibited two different molecular profiles: samples from obex resembled CWD whereas those from cerebrum were similar to the original scrapie inoculum. On further examination by WB using a panel of antibodies, the tissues from deer with scrapie exhibit properties differing from tissues either from sheep with scrapie or WTD with CWD. Samples from WTD with CWD or sheep with scrapie are strongly immunoreactive when probed with mAb P4, however, samples from WTD with scrapie are only weakly immunoreactive. In contrast, when probed with mAb’s 6H4 or SAF 84, samples from sheep with scrapie and WTD with CWD are weakly immunoreactive and samples from WTD with scrapie are strongly positive. This work demonstrates that WTD are highly susceptible to sheep scrapie, but on first passage, scrapie in WTD is differentiable from CWD.
*** After a natural route of exposure, 100% of white-tailed deer were susceptible to scrapie.
Scrapie in Deer: Comparisons and Contrasts to Chronic Wasting Disease (CWD)
Justin J. Greenlee of the Virus and Prion Diseases Research Unit, National Animal Disease Center, ARS, USDA, Ames, IA provided a presentation on scrapie and CWD in inoculated deer. Interspecies transmission studies afford the opportunity
After a natural route of exposure, 100% of white-tailed deer were susceptible to scrapie. Deer developed clinical signs of wasting and mental depression and were necropsied from 28 to 33 months PI. Tissues from these deer were positive for scrapie by IHC and WB. Tissues with PrPSc immunoreactivity included brain, tonsil, retropharyngeal and mesenteric lymph nodes, hemal node, Peyer’s patches, and spleen. While two WB patterns have been detected in brain regions of deer inoculated by the natural route, unlike the IC inoculated deer, the pattern similar to the scrapie inoculum predominates.
2011 Annual Report
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES Location: Virus and Prion Research Unit 2011 Annual Report
In Objective 1, Assess cross-species transmissibility of transmissible spongiform encephalopathies (TSEs) in livestock and wildlife, numerous experiments assessing the susceptibility of various TSEs in different host species were conducted. Most notable is deer inoculated with scrapie, which exhibits similarities to chronic wasting disease (CWD) in deer suggestive of sheep scrapie as an origin of CWD.
4.Accomplishments 1. Deer inoculated with domestic isolates of sheep scrapie. Scrapie-affected deer exhibit 2 different patterns of disease associated prion protein. In some regions of the brain the pattern is much like that observed for scrapie, while in others it is more like chronic wasting disease (CWD), the transmissible spongiform encephalopathy typically associated with deer. This work conducted by ARS scientists at the National Animal Disease Center, Ames, IA suggests that an interspecies transmission of sheep scrapie to deer may have been the origin of CWD. This is important for husbandry practices with both captive deer, elk and sheep for farmers and ranchers attempting to keep their herds and flocks free of CWD and scrapie.
White-tailed Deer are Susceptible to Scrapie by Natural Route of Infection
This work demonstrates for the first time that white-tailed deer are susceptible to sheep scrapie by potential natural routes of inoculation. In-depth analysis of tissues will be done to determine similarities between scrapie in deer after intracranial and oral/intranasal inoculation and chronic wasting disease resulting from similar routes of inoculation.
see full text ;
CWD, SCRAPIE, CATTLE, TSE ???
"CWD has been transmitted to cattle after intracerebral inoculation, although the infection rate was low (4 of 13 animals [Hamir et al. 2001]). This finding raised concerns that CWD prions might be transmitted to cattle grazing in contaminated pastures."
Please see ;
Within 26 months post inoculation, 12 inoculated animals had lost weight, revealed abnormal clinical signs, and were euthanatized. Laboratory tests revealed the presence of a unique pattern of the disease agent in tissues of these animals. These findings demonstrate that when CWD is directly inoculated into the brain of cattle, 86% of inoculated cattle develop clinical signs of the disease.
"although the infection rate was low (4 of 13 animals [Hamir et al. 2001])."
shouldn't this be corrected, 86% is NOT a low rate. ...
Terry S. Singeltary Sr. P.O. Box 42 Bacliff, Texas USA 77518
UPDATED CORRESPONDENCE FROM AUTHORS OF THIS STUDY I.E. COLBY, PRUSINER ET AL, ABOUT MY CONCERNS OF THE DISCREPANCY BETWEEN THEIR FIGURES AND MY FIGURES OF THE STUDIES ON CWD TRANSMISSION TO CATTLE ;
----- Original Message -----
From: David Colby
Sent: Tuesday, March 01, 2011 8:25 AM
Subject: Re: FW: re-Prions David W. Colby1,* and Stanley B. Prusiner1,2 + Author Affiliations
Dear Terry Singeltary,
Thank you for your correspondence regarding the review article Stanley Prusiner and I recently wrote for Cold Spring Harbor Perspectives. Dr. Prusiner asked that I reply to your message due to his busy schedule. We agree that the transmission of CWD prions to beef livestock would be a troubling development and assessing that risk is important. In our article, we cite a peer-reviewed publication reporting confirmed cases of laboratory transmission based on stringent criteria. The less stringent criteria for transmission described in the abstract you refer to lead to the discrepancy between your numbers and ours and thus the interpretation of the transmission rate. We stand by our assessment of the literature--namely that the transmission rate of CWD to bovines appears relatively low, but we recognize that even a low transmission rate could have important implications for public health and we thank you for bringing attention to this matter.
Warm Regards, David Colby
David Colby, PhDAssistant ProfessorDepartment of Chemical EngineeringUniversity of Delaware
SNIP...SEE FULL TEXT ;
UPDATED DATA ON 2ND CWD STRAIN
Wednesday, September 08, 2010
CWD PRION CONGRESS SEPTEMBER 8-11 2010
ADAPTATION OF CHRONIC WASTING DISEASE (CWD) INTO HAMSTERS, EVIDENCE OF A WISCONSIN STRAIN OF CWD
Chad Johnson1, Judd Aiken2,3,4 and Debbie McKenzie4,5 1 Department of Comparative Biosciences, University of Wisconsin, Madison WI, USA 53706 2 Department of Agriculture, Food and Nutritional Sciences, 3 Alberta Veterinary Research Institute, 4.Center for Prions and Protein Folding Diseases, 5 Department of Biological Sciences, University of Alberta, Edmonton AB, Canada T6G 2P5
The identification and characterization of prion strains is increasingly important for the diagnosis and biological definition of these infectious pathogens. Although well-established in scrapie and, more recently, in BSE, comparatively little is known about the possibility of prion strains in chronic wasting disease (CWD), a disease affecting free ranging and captive cervids, primarily in North America. We have identified prion protein variants in the white-tailed deer population and demonstrated that Prnp genotype affects the susceptibility/disease progression of white-tailed deer to CWD agent. The existence of cervid prion protein variants raises the likelihood of distinct CWD strains. Small rodent models are a useful means of identifying prion strains. We intracerebrally inoculated hamsters with brain homogenates and phosphotungstate concentrated preparations from CWD positive hunter-harvested (Wisconsin CWD endemic area) and experimentally infected deer of known Prnp genotypes. These transmission studies resulted in clinical presentation in primary passage of concentrated CWD prions. Subclinical infection was established with the other primary passages based on the detection of PrPCWD in the brains of hamsters and the successful disease transmission upon second passage. Second and third passage data, when compared to transmission studies using different CWD inocula (Raymond et al., 2007) indicate that the CWD agent present in the Wisconsin white-tailed deer population is different than the strain(s) present in elk, mule-deer and white-tailed deer from the western United States endemic region.
Prion Transmission from Cervids to Humans is Strain-dependent
Qingzhong Kong, Shenghai Huang,*Fusong Chen, Michael Payne, Pierluigi Gambetti and Liuting Qing Department of Pathology; Case western Reserve University; Cleveland, OH USA *Current address: Nursing Informatics; Memorial Sloan-Kettering Cancer Center; New York, NY USA
Key words: CWD, strain, human transmission
Chronic wasting disease (CWD) is a widespread prion disease in cervids (deer and elk) in North America where significant human exposure to CWD is likely and zoonotic transmission of CWD is a concern. Current evidence indicates a strong barrier for transmission of the classical CWD strain to humans with the PrP-129MM genotype. A few recent reports suggest the presence of two or more CWD strains. What remain unknown is whether individuals with the PrP-129VV/MV genotypes are also resistant to the classical CWD strain and whether humans are resistant to all natural or adapted cervid prion strains. Here we report that a human prion strain that had adopted the cervid prion protein (PrP) sequence through passage in cervidized transgenic mice efficiently infected transgenic mice expressing human PrP, indicating that the species barrier from cervid to humans is prion strain-dependent and humans can be vulnerable to novel cervid prion strains. Preliminary results on CWD transmission in transgenic mice expressing human PrP-129V will also be discussed.
Acknowledgement Supported by NINDS NS052319 and NIA AG14359.
Generation of a Novel form of Human PrPSc by Inter-species Transmission of Cervid Prions
Marcelo A. Barria,1 Glenn C. Telling,2 Pierluigi Gambetti,3 James A. Mastrianni4 and Claudio Soto1 1Mitchell Center for Alzheimer's disease and related Brain disorders; Dept of Neurology; University of Texas Houston Medical School; Houston, TX USA; 2Dept of Microbiology, Immunology & Molecular Genetics and Neurology; Sanders Brown Center on Aging; University of Kentucky Medical Center; Lexington, KY USA; 3Institute of Pathology; Case western Reserve University; Cleveland, OH USA; 4Dept of Neurology; University of Chicago; Chicago, IL USA
Prion diseases are infectious neurodegenerative disorders affecting humans and animals that result from the conversion of normal prion protein (PrPC) into the misfolded and infectious prion (PrPSc). Chronic wasting disease (CWD) of cervids is a prion disorder of increasing prevalence within the United States that affects a large population of wild and captive deer and elk. CWD is highly contagious and its origin, mechanism of transmission and exact prevalence are currently unclear. The risk of transmission of CWD to humans is unknown. Defining that risk is of utmost importance, considering that people have been infected by animal prions, resulting in new fatal diseases. To study the possibility that human PrPC can be converted into the infectious form by CWD PrPSc we performed experiments using the Protein Misfolding Cyclic Amplification (PMCA) technique, which mimic in vitro the process of prion replication. Our results show that cervid PrPSc can induce the pathological conversion of human PrPC, but only after the CWD prion strain has been stabilized by successive passages in vitro or in vivo. Interestingly, this newly generated human PrPSc exhibits a distinct biochemical pattern that differs from any of the currently known forms of human PrPSc, indicating that it corresponds to a novel human prion strain. Our findings suggest that CWD prions have the capability to infect humans, and that this ability depends on CWD strain adaptation, implying that the risk for human health progressively increases with the spread of CWD among cervids.
Biochemical and Biophysical Characterization of Different CWD Isolates
Martin L. Daus and Michael Beekes Robert Koch Institute; Berlin, Germany
Key words: CWD, strains, FT-IR, AFM
Chronic wasting disease (CWD) is one of three naturally occurring forms of prion disease. The other two are Creutzfeldt-Jakob disease in humans and scrapie in sheep. CWD is contagious and affects captive as well as free ranging cervids. As long as there is no definite answer of whether CWD can breach the species barrier to humans precautionary measures especially for the protection of consumers need to be considered. In principle, different strains of CWD may be associated with different risks of transmission to humans. Sophisticated strain differentiation as accomplished for other prion diseases has not yet been established for CWD. However, several different findings indicate that there exists more than one strain of CWD agent in cervids. We have analysed a set of CWD isolates from white-tailed deer and could detect at least two biochemically different forms of disease-associated prion protein PrPTSE. Limited proteolysis with different concentrations of proteinase K and/or after exposure of PrPTSE to different pH-values or concentrations of Guanidinium hydrochloride resulted in distinct isolate-specific digestion patterns. Our CWD isolates were also examined in protein misfolding cyclic amplification studies. This showed different conversion activities for those isolates that had displayed significantly different sensitivities to limited proteolysis by PK in the biochemical experiments described above. We further applied Fourier transform infrared spectroscopy in combination with atomic force microscopy. This confirmed structural differences in the PrPTSE of at least two disinct CWD isolates. The data presented here substantiate and expand previous reports on the existence of different CWD strains.
Zoonotic Potential of CWD: Experimental Transmissions to Non-Human Primates
Emmanuel Comoy,1,† Valérie Durand,1 Evelyne Correia,1 Aru Balachandran,2 Jürgen Richt,3 Vincent Beringue,4 Juan-Maria Torres,5 Paul Brown,1 Bob Hills6 and Jean-Philippe Deslys1
1Atomic Energy Commission; Fontenay-aux-Roses, France; 2Canadian Food Inspection Agency; Ottawa, ON Canada; 3Kansas State University; Manhattan, KS USA; 4INRA; Jouy-en-Josas, France; 5INIA; Madrid, Spain; 6Health Canada; Ottawa, ON Canada
†Presenting author; Email: firstname.lastname@example.org
The constant increase of chronic wasting disease (CWD) incidence in North America raises a question about their zoonotic potential. A recent publication showed their transmissibility to new-world monkeys, but no transmission to old-world monkeys, which are phylogenetically closer to humans, has so far been reported. Moreover, several studies have failed to transmit CWD to transgenic mice overexpressing human PrP. Bovine spongiform encephalopathy (BSE) is the only animal prion disease for which a zoonotic potential has been proven. We described the transmission of the atypical BSE-L strain of BSE to cynomolgus monkeys, suggesting a weak cattle-to-primate species barrier. We observed the same phenomenon with a cattleadapted strain of TME (Transmissible Mink Encephalopathy). Since cattle experimentally exposed to CWD strains have also developed spongiform encephalopathies, we inoculated brain tissue from CWD-infected cattle to three cynomolgus macaques as well as to transgenic mice overexpressing bovine or human PrP. Since CWD prion strains are highly lymphotropic, suggesting an adaptation of these agents after peripheral exposure, a parallel set of four monkeys was inoculated with CWD-infected cervid brains using the oral route. Nearly four years post-exposure, monkeys exposed to CWD-related prion strains remain asymptomatic. In contrast, bovinized and humanized transgenic mice showed signs of infection, suggesting that CWD-related prion strains may be capable of crossing the cattle-to-primate species barrier. Comparisons with transmission results and incubation periods obtained after exposure to other cattle prion strains (c-BSE, BSE-L, BSE-H and cattle-adapted TME) will also be presented, in order to evaluate the respective risks of each strain.
Pathological Prion Protein (PrPTSE) in Skeletal Muscles of Farmed and Free Ranging White-Tailed Deer Infected with Chronic Wasting Disease
Martin L. Daus,1,† Johanna Breyer,2 Katjs Wagenfuehr,1 Wiebke Wemheuer,2 Achim Thomzig,1 Walter Schulz-Schaeffer2 and Michael Beekes1 1Robert Koch Institut; P24 TSE; Berlin, Germany; 2Department of Neuropathology, Prion and Dementia Research Unit, University Medical Center Göttingen; Göttingen, Germany †Presenting author; Email: email@example.com
Chronic wasting disease (CWD) is a contagious, rapidly spreading transmissible spongiform encephalopathy (TSE) occurring in cervids in North America. Despite efficient horizontal transmission of CWD among cervids natural transmission of the disease to other species has not yet been observed. Here, we report a direct biochemical demonstration of pathological prion protein PrPTSE and of PrPTSE-associated seeding activity in skeletal muscles of CWD-infected cervids. The presence of PrPTSE was detected by Western- and postfixed frozen tissue blotting, while the seeding activity of PrPTSE was revealed by protein misfolding cyclic amplification (PMCA). The concentration of PrPTSE in skeletal muscles of CWD-infected WTD was estimated to be approximately 2000- to 10000-fold lower than in brain tissue. Tissue-blot-analyses revealed that PrPTSE was located in muscle- associated nerve fascicles but not, in detectable amounts, in myocytes. The presence and seeding activity of PrPTSE in skeletal muscle from CWD-infected cervids suggests prevention of such tissue in the human diet as a precautionary measure for food safety, pending on further clarification of whether CWD may be transmissible to humans.
now, let’s see what the authors said about this casual link, personal communications years ago. see where it is stated NO STRONG evidence. so, does this mean there IS casual evidence ????
“Our conclusion stating that we found no strong evidence of CWD transmission to humans”
From: TSS (216-119-163-189.ipset45.wt.net)
Subject: CWD aka MAD DEER/ELK TO HUMANS ???
Date: September 30, 2002 at 7:06 am PST
From: "Belay, Ermias"
Cc: "Race, Richard (NIH)" ; ; "Belay, Ermias"
Sent: Monday, September 30, 2002 9:22 AM
Subject: RE: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
In the Archives of Neurology you quoted (the abstract of which was attached to your email), we did not say CWD in humans will present like variant CJD.
That assumption would be wrong. I encourage you to read the whole article and call me if you have questions or need more clarification (phone: 404-639-3091). Also, we do not claim that "no-one has ever been infected with prion disease from eating venison." Our conclusion stating that we found no strong evidence of CWD transmission to humans in the article you quoted or in any other forum is limited to the patients we investigated.
Ermias Belay, M.D. Centers for Disease Control and Prevention
Sent: Sunday, September 29, 2002 10:15 AM
To: firstname.lastname@example.org; email@example.com; ebb8@CDC.GOV
Subject: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
Sunday, November 10, 2002 6:26 PM ......snip........end..............TSS
Thursday, April 03, 2008
A prion disease of cervids: Chronic wasting disease
2008 1: Vet Res. 2008 Apr 3;39(4):41
A prion disease of cervids: Chronic wasting disease
*** twenty-seven CJD patients who regularly consumed venison were reported to the Surveillance Center***,
full text ;
Friday, November 09, 2012
*** Chronic Wasting Disease CWD in cervidae and transmission to other species
Sunday, November 11, 2012
*** Susceptibilities of Nonhuman Primates to Chronic Wasting Disease November 2012
Friday, December 14, 2012
Susceptibility Chronic Wasting Disease (CWD) in wild cervids to Humans 2005 - December 14, 2012
Saturday, March 09, 2013
Chronic Wasting Disease in Bank Voles: Characterisation of the Shortest Incubation Time Model for Prion Diseases
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]
*** NOR IS THE FDA recalling this CWD positive elk meat for the well being of the dead elk ;
Wednesday, March 18, 2009 Noah’s Ark Holding, LLC, Dawson, MN RECALL Elk products contain meat derived from an elk confirmed to have CWD NV, CA, TX, CO, NY, UT, FL, OK RECALLS AND FIELD CORRECTIONS: FOODS CLASS II
a) Elk Meat, Elk Tenderloin, Frozen in plastic vacuum packaging. Each package is approximately 2 lbs., and each case is approximately 16 lbs.; Item number 755125, Recall # F-129-9;
b) Elk Meat, Elk Trim, Frozen; Item number 755155, Recall # F-130-9;
c) Elk Meat, French Rack, Chilled. Item number 755132, Recall # F-131-9;
d) Elk Meat, Nude Denver Leg. Item number 755122, Recall # F-132-9;
e) Elk Meat, New York Strip Steak, Chilled. Item number 755128, Recall # F-133-9;
f) Elk Meat, Flank Steak Frozen. Item number 755131, Recall # F-134-9;
Elk Meats with production dates of December 29, 30, and 31
Recalling Firm: Sierra Meats, Reno, NV, by telephone on January 29, 2009 and press release on February 9, 2009.
Manufacturer: Noah’s Ark Holding, LLC, Dawson, MN. Firm initiated recall is ongoing.
Elk products contain meat derived from an elk confirmed to have Chronic Wasting Disease (CWD).
VOLUME OF PRODUCT IN COMMERCE
NV, CA, TX, CO, NY, UT, FL, OK
Monday, February 09, 2009
Exotic Meats USA Announces Urgent Statewide Recall of Elk Tenderloin Because It May Contain Meat Derived From An Elk Confirmed To Have CWD
Cross-sequence transmission of sporadic Creutzfeldt-Jakob disease creates a new prion strain
Date: August 25, 2007 at 12:42 pm PST
our results raise the possibility that CJD cases classified as VV1 may include cases caused by iatrogenic transmission of sCJD-MM1 prions or food-borne infection by type 1 prions from animals, e.g., chronic wasting disease prions in cervid. In fact, two CJD-VV1 patients who hunted deer or consumed venison have been reported (40, 41). The results of the present study emphasize the need for traceback studies and careful re-examination of the biochemical properties of sCJD-VV1 prions.
Wednesday, March 18, 2009
Noah's Ark Holding, LLC, Dawson, MN RECALL Elk products contain meat derived from an elk confirmed to have CWD NV, CA, TX, CO, NY, UT, FL, OK RECALLS AND FIELD CORRECTIONS: FOODS CLASS II
Saturday, July 6, 2013
Small Ruminant Nor98 Prions Share Biochemical Features with Human Gerstmann-Sträussler-Scheinker Disease and Variably Protease-Sensitive Prionopathy
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
Saturday, December 15, 2012
Bovine spongiform encephalopathy: the effect of oral exposure dose on attack rate and incubation period in cattle -- an update 5 December 2012
Thursday, June 6, 2013
BSE TSE PRION USDA FDA MAD COW FEED COMPLIANCE REPORT and NAI, OAI, and VAI ratings as at June 5, 2013
Tuesday, June 11, 2013
Weld County Bi-Products dba Fort Morgan Pet Foods 6/1/12 significant deviations from requirements in FDA regulations that are intended to reduce the risk of bovine spongiform encephalopathy (BSE) within the United States
Friday, December 14, 2012
Susceptibility of domestic cats to chronic wasting disease
Thursday, May 30, 2013
World Organization for Animal Health (OIE) has upgraded the United States' risk classification for mad cow disease to "negligible" from "controlled", and risk further exposing the globe to the TSE prion mad cow type disease
U.S. gets top mad-cow rating from international group and risk further exposing the globe to the TSE prion mad cow type disease
Tuesday, June 25, 2013
Emerging Infectious Diseases (-$2.425 million) This request includes funds to focus on necessary activities for prion disease
A FOOLISH MOVE BY THE GOVERNMENT...TSS