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From: TSS ()
Subject: Docket No: 2002N-0273 (formerly Docket No. 02N-0273) Substances Prohibited From Use in Animal Food and Feed PAUL BROWN
Date: January 20, 2006 at 9:31 am PST

December 20,2005

Division of Dockets Management (HFA-305)

Food and Drug Administration

5630 Fishers Lane

Room 1061

Rockville, MD 20852

Re: Docket No: 2002N-0273 (formerly Docket No. 02N-0273)

Substances Prohibited From Use in Animal Food and Feed

Dear Sir or Madame:

As scientists and Irecognized experts who have worked in the field of TSEs for

decades, we are deeply concerned by the recent discoveries of indigenous BSE infected

cattle in North America and appreciate the opportunity to submit comments to this very

important proposed rule We strongly supported the measures that USDA and FDA

implemented to protect public health after the discovery of the case of bovine spongiform

encephalopathy (BSE) found in Washington State in 2003. We know of no event or

discovery since then that could justify relaxing the existing specified risk material

(SRM) and non-ambulatory bans and surveillance that were implemented at that time.

Further, we strongly supported the codification of those changes, as well as additional

measures to strengthen the entire feed and food system. The discovery of additional

cases of indigenous BSE in North America since that time has validated our position and

strengthened OUT convictions.

We caution against using the 18 month enhanced surveillance as a justification to relax or

impede further actions. While this surveillance has not uncovered an epidemic, it does

not clear the US cattle herd from infection. While it is highly likely that US and

Canadian cattle were exposed to BSE prior to the 1997 feed ban, we do not know how

many cattle were infected or how widely the infection was dispersed. BSE cases are

most likely clustered in time and location, so while enhanced surveillance provides an 18

month snapshot, it does uot negate the fact that US and Canadian cattle were exposed to

BSE. We also do not know in any quantitative or controlled way how effective the feed

ban has been, especially at the farm level. At this point we cannot even make a thorough

assessment of the USDA surveillance as details such as age, risk category and regional

distribution have not been released.

A number of countries initially attempted to take partial steps in regard to feed controls

only to face repeated disappointments in predicted downturns of the epidemic course.

We in North America could do this experiment all over again, waiting for each new

warning before adding more stringency to our control measures, or we can benefit from

the experience of others and take decisive measures now to arrest any further

development of underlying cases that is implicit in those already discovered to date.

The discovery of 5 indigenous North American cases, including one born after the

implementation of the current feed ban, should provide the necessary incentive to

implement, monitor and enforce a comprehensive and protective feed ban that is more

congruent with the measures that have been proven to be effective throughout the world.

In particular, we urge the FDA to act without f&ther delay to strengthen the animal feed

regulations by implementing the program proposed by the Canadian Food Inspection

Agency (CFIA) in the December 11, 2004 Gazette. This includes removing all specified

risk materials (SRMs) and deadstock from all animal feed. We also urge that the FDA

discontinues the legal exemptions which allow ruminant protein to be fed back to

ruminants (with the excelption of milk). Many of these exemptions do not exist in other


Bovine products and byproducts are used for both food and pharmaceuticals. These

human uses require the highest level of safety. Because of the hardy nature of the BSE

agent and its high potential for cross contamination, the most effective way to protect

bovine products and bovine derived materials from contamination by BSE is to ensure

that infected animals or carcasses never enter processing plants. The goal would be to

discover and remove infected animals fi-om production as early as possible in the

infection and long before they wouid be sent to slaughter. Until we have diagnostic tools

powerful enough to allow us to discover the disease early in its prolonged pre-clinical

incubation, we have to rely on the next best strategy which is to prevent any exposure

through feed. The exemptions in the current ban as well as in the newly proposed rule

make this difficult if not impossible, as they still provide legal avenues for ruminants to

consume potentially contaminated ruminant protein.

It is our opinion that the Iproposed rule falls woetilly short in effective measures to

minimize the potential for further transmissions of the disease. By the FDA’s own

analysis, exempted tissues (such as distal ileum, DRGs, etc) contain approximately 10%

of the infectivity in affected animals. Thus the proposed rule still allows the possibility

for cattle to be exposed to BSE through:

1. Feeding of materials currently subject to legal exemptions from the ban (e.g.,

poultry litter, plate waste)

2. Cross feeding (the feeding of non-ruminant rations to runiinants) on farms; and

3. Cross contamination of ruminant and non-ruminant feed

We are most concerned that the FDA has chosen to include a provision that would allow

tissues from deadstock into the feed chain. We do not believe that down or dead stock


should be allowed into the food or feed chain whatever the age of the animal and whether

or not the CNS tissues are removed. We do not support the provision to allow removal of

brain and spinal cord from deadstock over 30 months for a number of reasons. This

category of animals contains the highest level of infectivity and that infectivity is in other

tissues besides just brain and spinal cord. Recent improvements in the BSE bioassay,

have now made it possible to detect BSE infectivity 1000 time more efficiently than

before. This assay has revealed the presence of BSE infectivity in some but not all

peripheral nerves and in one muscle. (Buschmann and Groschup, 2005) This published

and peer reviewed work is consistent with other publicly reported studies in Japan where,

by western blot testing, ,prions were found in the peripheral nerves of a naturally infected

94-month-old cow. We feel that the studies as reported above have merit. The current

studies not only re-etiorce the risk of down and deadstock but also appear to provide

additional information that these animals may be a potential source of greater levels of

infectivity into the feed .system. We also doubt that brain and spinal cord can be

completely removed especially during warmer weather. Given the biological

composition of these tissues, they are predisposed to rapid autolysis.

As world wide surveillance for BSE increases, several atypical cases of bovine TSE have

been discovered. These cases either show no clinical signs, or present as ‘downers’, and

have an atypical neuropathology with respect to lesion morphology and distribution,

causing problems in both clinical and post-mortem diagnosis. The origin of the cases are

unclear but they suggest that even should typical BSE be eliminated, there may be other

TSE diseases of cattle that could result by “mutation” and selection. Refeeding of

contaminated protein could potentially perpetuate transmission much like typical BSE.

An effective feed ban could prevent the expansion of such strains. We also note that

there are other species which are susceptible to BSE and the current regulations allow for

SRMs to be included in feed for these animals.

For BSE to be perpetuated, the animal production system must have a source of agent and

a means by which cattle or other susceptible species are exposed to this agent. We feel

that in North America, the source and routes of exposure still exist, hence allowing for

the continued recycling of BSE. We have detailed the scientific justifications for our

position below.

Source of the agent: SRMs (Specified Risk Materials) r

SRMs, as defined by the USDA, are tissues which, in a BSE infected animal, are known

to either harbor BSE i&:ctivity or to be closely associated with infectivity. If SRMs are

not removed, they may introduce BSE infectivity and continue tq provide a source of

animal feed contamination. For example, the skull and vertebral column which encase

the brain and spinal cord, respectively, can be assumed to have gross contamination.

Rendering will reduce infectivity but it will not totally eliminate it. This is significant as

research in the United Kilngdom has shown that a calf may be infected with BSE by the

ingestion of as little as AI01 gram of untreated brain.

The tissue distribution of infectivity in BSE infected cattle has primarily been determined

by 3 studies conducted in the United Kingdom all of which had limitations.

In two of the studies, bioassays were done in mice which are at least 1000 fold less

sensitive to BSE infection than cattle themselves. Only higher titers of infectivity can be

detected by this method. These investigations found infectivity in the brain, spinal cord,

retina, trigeminal ganglia, dorsal root ganglia, distal ileum and bone marrow (the bone

marrow finding was from one animal). Infectivity was found in distal ileum of

experimentally infected calves beginning six months after challenge and continuing at

other intervals throughout life. (Wells et. al., 1994; 1998). The bioassay study in calves

has produced similar results and in addition infectivity has been found in tonsil. The

study is still in progress. Another project has found infectivity in the lymphoid tissue of

third eyelid from naturally infected animals. (Dr. Danny Matthews, UK DEFRA,

personal communication).

While bioassay in cattle is far preferable to mice in terms of sensitivity, cattle

nevertheless present their own limitations in terms of the long incubation time and the

limited number of anim& that can be used for assay compared to rodents. As a

consequence the significance of the negative finding for many tissues is questionable. In

fact, by the end of 2004 there was increasing evidence in species other than cattle that

peripheral nerves and muscle have infectivity. (Bosque et al., 2002; Glatzel et al.,

2003;Bartz et al., 2002; Androletti et al., 2004; Mulcahy et al., 2004; Thomzig et al.,

2003; Thomzig et al., 2004)

In some of these species, studies indicate that the agent migrates to the brain and spinal

cord, replicates to high levels in the CNS and then spreads centrifugally from the spinal

cord back down through the spinal neurons to the junction of the nerves and muscle into

the muscle cells themselves. A recent German study (Buschmann and Groschup, 2005)

examined nerves and muscle from a cow naturally infected with BSE and found tbat

infectivity was present in several peripheral nerves and one muscle. The method of

detection was bioassay in bovinized transgenic mice that show the same or greater

sensitivity to transmission of BSE as cattle. This research concurs with findings by

Japanese scientists that BSE infectivity is present in peripheral nerves at least in the

clinical stage of disease.

It is our opinion that there is increasing evidence that the pathogenesis of BSE might not

be entirely different from TSEs in other species at the point of clinical disease in that

there is peripheral involvement. We feel that the studies as reported above have merit.

The current studies not only re-enforce the risk of down and deadstock but also appear to

provide additional information that these animals may be a potential source of greater

levels of infectivity into the feed system.

In the event that FDA may confer with USDA about the risks associated with peripheral

nerves we want to point out one issue. In the recent publication of the final rule on the


importation of whole cuts OF boneless beef from Japan, 9 CFR Part 94 [Docket No. 05-

004-21 RIN 0579-AB93, we disagree with the interpretation provided by USDA, APHIS.

APHIS seems to discount the studies conducted by Groschup et al. 2005. on the basis that

the transgenic mouse bioassay that they used may be too sensitive. In taking this position

they have failed to realize that the point oFan assay is to reveal in which tissues the

infectivity resides and its relative concentration to brain or spinal cord. For this purpose,

no assay can be too sensitive. Of course, the probability of an actual infection will he

affected by the efficiency of infection which will be a function of dose, route of exposure

and any host barrier effects that are present.

We would also like to point out a factual error in the conclusion. APHIS states, “Given

these factors, APHIS has determined that the finding of l3SE infectivity in facial and sciatic nerves

of the transgenic mice is nalt directly applicable to cattle naturally infected with BSE. Therefore,

we do not consider it necessary to make any adjustments to the risk analysis for this rulemaking

or to extend the comment Fleriod to solicit additional public comment on this issue.” It is incorrect

that the infectivity was found in the peripheral nerves of transgenic mice. The peripheral

nerves were harvested from a cow naturally infected with BSE. Transgenic mice were

used as a bioassay model.

From [Docket No. 05-004-21 RIN 0579-AB93:

“Peripheral Nerves

Issue: Two commenters stalted that the underlying assumption of the proposed rule. that whole

cuts of boneless beef from #Japan will not contain tissues that may carry the BSE agent, is no

longer valid because researchers have found peripheral nervous system tissues, including facial

and sciatic nerves, that contain BSE infectivity.U One of these commenters requested API-W to

explain whether and what additional mitigation measures are needed to reduce the risks that

these tissues may be present in Japanese beef. This commenter further requested an additional

comment period to obtain public comments to treat this new scientiic finding.

\2\ Bushmann, A., and Groschup, M.; Highly Bovine Spongiform

Encephalopathy-Sensitive Transgenic Mice Confirm the Essential

Restriction of Infectivity to the Nervous System in Clinically

Diseased Cattle. The Journal of Infectious Diseases, 192: 93442,

September 1, 2005.

Response: APHIS is familiar with the results of the study mentloned by the commenters in which

mice, genetically engineered to be highly susceptible to BSE and to overexpress the bovine prion

protein, were inoculated with tissues from a BSE-infected cow. This study demonstrated low

levels of infectivity in the mouse assay in the facial and sciatic nerves of the peripheral nervous

system. APHIS has evaluated these findings in the context of the potential occurrence of

infectivity in the peripheral nerves of cattle and the corresponding risks of the presence of

infectivity in such tissues resulting in cattle or human exposure to the BSE agent. The results

from these experiments in genetically engineered mice should be interpreted with caution, as the

findings may be influenced by the overexpression of prion proteins and may not accurately

predict the natural distribution of BSE infectivity in cattle. Further, the overexpression of priori


proteins in transgenic mice may not accurately mimic the natural disease process because the

transgenic overexpressing mice have been shown to develop spontaneous lethal neurological

disease involving spongifolrm changes in the brain and muscle degeneration.\3\ In addition, the

route of administration to the mice was both intraperitoneal and intracerebral, which are two very

efficient routes of infection as compared to oral consumption. Given these factors, APHIS has

determined that the finding of BSE infectivity in facial and sciatic nerves of the transgenic mice is

not directly applicable to cattle naturally infected with BSE. Therefore, we do not consider it

necessary to make any adjustments to the risk analysis for this rulemaking or to extend the

comment period to solicit additional public comment on this issue.”

Source of the agent: Deaalstock

The total amount of TSE infectivity in a TSE infected animal increases steadily

throughout the infection and exponentially once the infectivity reaches the brain.

Infected individuals only exhibit recognizable clinical signs once infectivity titers have

reached high levels in the brain. Surveillance data collected throughout Europe indicates

there is a much greater likelihood for BSE to be detected in dead or down cattle than

from healthy normal animals. This has so far also been borne out by the experience in

North America. Animals that die of BSE harbor the greatest amount of agent that can be

produced by the disease. Leaving the tissues from the highest risk category of cattle in

the animal feed chain will effectively nullify the purported intent of this regulation. This

point is supported by the 2001 Harvard risk assessment model that demonstrated that

eliminating dead and downer, 4D cattle, from the feed stream was a disproportionately

effective means of reducing the risk of re-infection.

“The disposition of cattle thot die on the farm would also huve a substantial influence on

the spread of BSE if the disease were introduced ” The base case scenario showed that

the mean rota? number oj’IDS0.s (i.e., dosage suficient to infecf 50percent of exposed

cattle) f;om healthy animals at slaughter presented to the foodfeed system was 1500.

The mean total number yf IDSOsfiom adult cuttle deadstockpresented fo the feed system

was 3 7,000. This illustrates the risk of “40 cattle ” (i.e.. deadstock).

From the Harvard Risk Assessment, 200 1, Appendix 3A Base Case and Harvard Risk

Assessment, 200 1 Executive Summary

It is likely that these numbers would have to be adjusted upwards, if the UK attack rate

and Groschup data were considered.

Inflammation and TSErr

There have been 3 recent peer reviewed publications which indicate that chronic

ir&unmatory conditions in a host with a TSE may induce priori replication in, or

distribution to organs previously thought to be low or no risk. They are as follows:


1 _ Chronic Lymphocytic Inflammation Specifies the Organ Tropism of Prions

(Heikenwalder et. al. 2005 >~xx .sci~:n~c\rpl-css.~~r~/~O .lunuarv 2005/ Parrc l/

&).I 1zois~icllcc.l lOh4hO)

2. Coincident Scrapie Infection and Nephritis Lead to Urinary Priori Excretion

(Seeger et al., Science 14 October 2005:Vol. 310. no. 5746, pp. 324 - 326

DOI: lO.l126/science. 1118829)

3. PrPS” in mammary glands of sheep affected by scrapie and mastitis (Ligios C., et

al. Nature Medicine, 11. 3 137 - 1138, 2005)

These studies from the Aguzzi laboratory warn that concurrent chronic inflammatory

disease could dramatically alter the distribution of BSE infectivity in infected cattle.

Down and dead stock are at higher risk for both BSE and other systemic conditions. If

the results reported above are also applicable to cattle, the carcasses of dead and down

stock affected by BSE might contain even higher levels of infectivity, or contribute

infectivity via tissues thai. are not ordinarily at risk in normal animals.

Exposure: tndustry Practices or Exemptions which may pose a risk

Poultry Litter

In the United States poultry litter can be fed to cattle. There are two potential sources of

risk from poultry litter. Poultry litter not only consists of digested feed but also of feed

which spills from the cages. As a consequence, the practice of feeding litter back to

cattle is by its nature non--compliant with the current feed ban if the poultry themselves

are being fed ruminant protein. Given that ruminant protein can no longer be fed to

ruminants in the United States and that most. if not all. countries will no longer import

North American ruminant MBM, an even larger part of poultry diets is now ruminant

MBM. Spillage provides a direct link to back to cattle but feces are also likely to contain


There is no reason to expect that TSE infectivity would be inactivated by passage through

the poultry gut, and only a slim possibility that composting would reduce infectivity at

all. Thus poultry feces are another potential route of transmission back to cattle.

Evidence for this comes from rodent experiments where infectivity was demonstrated in

the feces after being fed: “Laboratory experiments show that mice orally challenged with

scrapie have detectable infectivity that passes through the gut. Gut contents and fecal

matter may therefore contain infectivity, and it is noted that in experimental oral

challenges in cattle conducted in the UK, feces must be treated asamedical waste for one

month following the challenge. It is concluded that digestive contents and fecal material

from livestock or poultry currently being fed with MBM potentially contaminated with

BSE should not be used a.s a feed ingredient for animal feed.” [Proceedings: Joint

WHO/FAO/OIE/ Technical Consultation on BSE: public health, animal health and

trade. Paris, lo-14 June 2001; and Alan Dickinson, personal communication].

It may be possible to remove the risk from poultry litter by sterilization. However, unless

or until a method can be developed and validated, poultry litter should be banned from

ruminant feed.

Ruminant Blood

In contrast with humans, sheep, monkeys, mice and hamsters, including sheep and mice

infected with BSE and humans infected with vCJD considered identical to BSE, no

infectivity has so far been demonstrated in the blood of BSE infected cattle. However,

we consider it unlikely that cattle are the sole outlier to what has been a consistent finding

in all other TSE diseases where the measurement has been made with sufficient

sensitivity to detect the low levels of infectivity that are present in blood. Rather, this

failure is more likely the result of the very small volumes of blood that were used for the

inoculations (less than 1 ml), whereas whole transfusions were administered to assay

animals in the published .sheep scrapie/BSE experiments. If blood is infected then all

vascularized tissues can bc expected to contain some infectivity in proportion to the

content of residual blood..

Micro emboli are a possible source of blood-borne agent that could be at much higher

titer than blood itself, in slaughtered cattle carrying BSE infection. Stunning can release

micro emboli of brain tissue into the circulatory system from where they can be

distributed to other tissues in the few moments before the exsanguination and

death. (Anil, et al, 2001a & b; Anil et al, 2002; Love, et al, 2000). This source of

infection couid extend a higher infectivity risk to tissues that would otherwise be at low

risk, thereby allowing exposure of cattle through any of the legal exemptions and

potentially producing a feed and food risk. Blood-borne contamination may be a special

problem where spray-dried blood is being used as a milk replacer for calves, as it is

thought that young animals are especially susceptible to infection.

Certainly, blood and bloald proteins should not be used as feed without conclusive

evidence that they are saf’e.

Unfiltered Tallow

Ruminant tallow is exempted from the current feed ban. Tallow contains protein

impurities (i.e. MBM) that could be a source of TSE infectivity. There are no impurity

level requirements for this tallow. It has been reported that it is standard practice to

produce tallow which has an impurity level of _ 15% or below, but it is not clear that this

is fully adequate to remove the risk of transmission and there is no requirement to meet

even this standard. We urge that protein contaminants be excluded from tallow and that

SRMs also be removed.


Plate Waste

Plate waste is not limiteld to meat (muscle tissue). For example, cuts that include a

portion of the spinal cor’d or that are contaminated by cord or ganglia during preparation

could contain high levels of infectivity if derived from a TSE infected animal late in the

preclinical stage of infection. At best this material would only be exposed to normal

cooking temperatures. USDA, APHIS experience with the Swine Health Protection Act

has revealed that plate waste also includes uncooked trimmings and bones. Although the

current FDA regulation requires the plate waste be treated again, there are no

specifications which would render a TSE agent inactive. Of greatest risk would be any

bovine source of infectivity but also sheep scrapie, although not known to be a risk for

human consumption, is one of the possible origins of BSE. The sheep scrapie agent is

known to be widely dispersed including relatively high titers in lymphoid as well as

nervous tissue. We support the USDA’s opposition to the exemption of “plate waste” as

stated in written comments since 1997.

Exposure: Cross Feeding and Cross Contamination

The UK epidemiology has clearly shown that BSE contaminated feed is the primary if

not sole vehicle for the transmission of BSE between cattle. Moreover, results from the

United Kingdom’s attack: rate study indicate that it does not take much exposure to

transmit BSE to cattle. FLecent results from the attack rate study which is still in progress

have found that _ 1 g of brain transmitted BSE by the oral route to 3 cows out of 15 thus

far, and .Ol and .OOl gr of brain have transmitted BSE (1 cow out of 15). (Danny

Matthews, DEFRA presentation at TAFS meeting, Washington, DC April 2004).

Rendering may reduce infectivity but it does not eliminate it. (Taylor et al, 1995; Taylor

et al, 1997; Schreuder et al, 1998). Given that BSE can be transmitted to cattle via an

oral route with just .OO 1 gram of infected tissue, it may not take much infectivity to

contaminate feed and kee:p the disease recycling. This is especially true in countries like

the US and Canada which do not have dedicated lines and equipment to manufacture and

process feed for ruminants and non-ruminants.

In addition, epidemiological investigations in European countries have shown that cross

feeding and cross contamination on farm can be a significant vehicle for continued BSE

transmission even after feed bans are well established. Cross feeding is the practice of

feeding meal for poultry or pigs or pet food (which can legally contain ruminant MBM)

to cattle on the same farm. This is usually due to simple human error or negligence.

(Hoinville, 1994; Hoinville et al, 1995; Doherr et al, 2002% Stevenson et al, 2000)

FDA, CVM reports that compliance with the existing feed ban is high. For the most part

this does not include the compliance level on the farm. There are hundreds of thousands

of farms in the US. Many of these have multiple species- That is, they raise cattle, pigs,

chickens etc., on the same premises. The sheer numbers of farms make it very difficult to

assure compliance on farm and to adequately cover all farms by inspection- Even if the

rendering industry and feed industry can maintain 100% compliance at their facilities, if a

producer inadvertently feeds chicken feed containing bovine MBM to their cattle, they

negate a perfect compliance rate higher in the chain. Recent data from the Harvard BSE

risk assessment suggest that the level of misfeeding on farms plays a significant role in

the ability of the agent to recycle. In fact George Gray, principal investigator for the

study, stated that if, in the United States, misfeeding were to occur at a level of 15%, the

RO would be over 1, indicating that the BSE level would not be declining. (George Gray

presentation at the Meeting on BSE Prevention in North America: An Analysis of the

Science and Risk; January 27,2005, Washington, DC.)

The May 2003 Canadian BSE case illustrates the difficulty of on farm enforcement and

its serious ramifications. The BSE positive cow was rendered and the MBM distributed

to various locations. Two of these locations were poultry farms which mixed their own

feed. The farms also had cattle. The subsequent investigation could not eliminate the

possibility that the cattle had been fed the same feed as the poultry. The cattle on these

farms were completely depopulated.

Human error is extremel:y difftcult to prevent, and managing the risk through

enforcement is problematical when confronted with the extreme logistical challenges of

on farm monitoring. By eliminating the highest risk materials (SRMs and deadstock)

which could introduce infectivity into the feed stream, the MBM resulting from

processing becomes inherently safer. If mistakes are then made on farm, they no longer

contribute to the recycling of BSE.

Exposure: Susceptibility of other Species


A transmissible spongifoim encephalopathy has been diagnosed in eight species of

captive wild ruminants as well as exotic felines (cheetahs, pumas, a tiger and an ocelot)

and domestic cats (Wyatt 1991). There have been over 80 domestic cat cases of Feline

Spongiform Encephalopathy (FSE) in Great Britain, and cats in Norway, Northern

Ireland, Lichtenstein and Switzerland. The agent isolated from several of these cases is

indistinguishable from BSE in cattle using strain typing in mice, duggesting that FSE is

actually BSE in exotic and domestic cats. Epidemiological evidence suggests BSE

contaminated feed to be the probable source of infection in these species. (MAFF

Progress Report, June 1997), thus providing additional supporting evidence for the

dangers of BSE contaminated feed and reinforcing the necessity of removing all sources

of potential contamination from the feed stream

Other species

Studies conducted at the National lnstitutes of Health Rocky Mountain Laboratory

caution against assuming that animals which do not become clinically ill are not infected.

It is unknown if certain animals may become carriers, i.e., become infected, shed agent

but do not progress to clinical disease. Infection of certain rodent species with different

TSE strains suggests the possibility of a carrier state (Race and Chesebro, 1998; Race et.

al, 2001, Race et al., 2002). In the more recent studies, mice were inoculated with 263K

hamster scrapie. There was a prolonged period (approximately one year) where there was

no evidence of replication of infectivity. Furthermore, there was no evidence of PrPres

during this phase of inactive persistence, which was followed by a period of active

replication of infectivity and agent adaptation. In most cases, PrPres was not detected in

the active phase as well. It is important to determine if this persistence and adaptation

occurs in other species exposed to TSEs as it may have significance in feeding programs

which continually expose other species to BSE infectivity. For example, if BSE infected

brain and spinal cord are continually fed to certain species, it may be possible for the

agent to persist and adapt in these new species. Over time, the ‘resistant’ species may

become a source of agenl. The results of Race and colleagues, warns that an inactive

persistent phase might not produce detectable PrPres, yet there would be infectivity (Race

et. al., 2001).

Pigs displayed evidence of TSE infection after exposure to BSE by 3 distinct parer&ml

routes. Evidence of infectivity was found in the CNS, stomach, intestine and pancreas

(Dawson et. al., 1990). CIral transmission has also been attempted in swine, but after an

observation period of 84 months there was neither clinical nor pathological evidence of

infection (Dawson et. al., 1990). Parenteral and oral transmission has also been

attempted in chickens with no evidence of disease. Tissues from the BSE-challenged

pigs and chickens were inoculated into susceptible mice to look for residual infectivity,

but to date none has been found. In both instances the detection sensitivity was limited

by the use of mice for bioassay instead of same species transmissions into cattle (or pigs

and chickens).

If any of these scenarios played out and inapparent infections became established in

commercial species, those species could become reservoirs for reinfection of cattle and

perpetuation or reintroduction of the epidemic. We also do not know if atypical cases of

BSE are more pathogenic for other species and if chronic inflammation may influence the

susceptibility of other species. We offer these possibilities to reitiorce the need to

eliminate all possible sources of infectivity from the feed stream.

In January 2005, the European Union announced that BSE had been confirmed in a goat

in France illustrating that the disease can be naturally transmitted to one of the small

ruminants. The potential ramifications of this and the logistical chaIlenges associated

with controlling BSE in sheep or goats also provides a justification for removing SRMs

from all animal feed. Although these species are covered under the current regulations

the cross contamination and cross feeding aspects stated for cattle are applicable.

The need to remove high risk material from all animal feed is also supported by other

bodies with expertise in the field of TSEs:

Recommendations of the World Health Organization (WHO)

The World Health Organization (WHO) has issued the following recommendations for

countries with BSE or those where a known exposure exists:

l No part or product of any animal which has shown signs of a TSE should enter any

food chain (human or animal). In particular:

o All countries must ensure the killing and safe disposal of all parts or products

of such animals so that TSE infectivity cannot enter any food chain.

o Countries sholuld not permit tissues that are likely to contain the BSE agent to

enter any food chain (human or animal).

From the report of a WHO Consultation on Public Health Issues related to Human and

Animal Transmissible Spongiform Encephalopathies WHO/EMC/DIS 96.147, Geneva,

2-3 April 1996.

Office of International El-

The OIE is recommendinlg that a list of SRMs which include brain, spinal cord, eyes,

skull and vertebral column be removed from preparations used for food, feed, fertilizer,

etc. If these tissues sholtld not be traded we feel that they should not be used in domestic

products either.

BSE Code Article

“From cattle, originating from a country or zone with a minimal BSE risk, that were at the time of

slaughter over 30 months of age, the following commodities, and any commodity contaminated by them,

should not be traded for the preparation of Food, feed, fertilizers, cosmetics, pharmaceuticals including

biologicals, or medical device:s: brains, eyes and spinal cord, skull, vertebral column and derived protein

products. Food, feed, fertilizers, cosmetics, pharmaceuticals or medical devices prepared using these

commodities should also not be traded.”


In conclusion we urge the: FDA to implement, monitor and enforce a comprehensive and

protective feed ban that is more congruent with the measures that have been proven to be

effective in other countries that have experienced BSE. We do not feel that we can

overstate the dangers from the insidious threat from these diseases and the need to control

and arrest them to prevent any possibility of spread.

We also wish to emphasize that as scientists who have dedicated substantive portions of

our careers to defining the risks from TSEs as well as developing strategies for managing

those risks, we are confident that technical solutions will be found for many of the

challenges posed by these diseases. Thus, we urge the FDA to frame its regulations in

terms that allow for the future use of any banned material if it can be proven safe for a

given application.



Paul W. Brown, M.D.

Medical Director, USPH[S, and Senior Investigator, NIH (retired)

Consultant, TSE Risk Management

78 15 Exeter Rd.

Bethesda, MD 208 14

Fax 301-652-43 12

Email: paLII\\ hr-c~~~rl~~/‘~c)m~as~.rlct -----

Neil R Cashman MD

Professor, Department 0-C Medicine (Neurology)

Diener Chair of Neurode:generaGve Diseases

Centre for Research in Neurodegenerative Diseases

6 Queen’s Park Crescent West

Toronto Ontario M5S3H2

Ph: 416-978-1875

Fax: 4 16-978- 1878


Linda A. Detwiler, DVM

Consultant, TSE Risk Management

225 Hwy 35

Red Bank, NJ 07701

Ph 732-74 l-2290

Fax 732-741-775 1

Email: l.~\Vc~92’rr’ac,l.c0111.

Laura Manuelidis, MD

Professor and Head of Neuropathology,

Department of Surgery and Faculty of Neurosciences

Yale Medical School

333 Cedar St.

New Haven, CT 065 10

email: I~IL~ra.~~~ar~clclirli~~~~~~alc.cdi~

Tel: 203-785-4442

Jason C. Bar-k, Ph.D.

Assistant Professor

Department of Medical Microbiology and Immunology

Creighton University

2500 California Plaza

Omaha, NE 68178

(402) 280- 18 11 voice

(402) 280-l 875 fax

jbartz@creighton .edu

Robert B. Petersen, Ph.D.

Associate Professor of Pathology and Neuroscience

Case Western Reserve University

5- 123 Wolstein 13~1ilding

2 103 Cornell Road

Cleveland, OH 44 106-26122

Phone 216-368-6709

FAX 360-838-9226

Email rhp~,-c\\~~.c~!t~

Robert G. Rohwer, Ph.D.

Director, Molecular Neurovirology Laboratory

Veterans Affairs Medicall Center

Medical Research Service 151

Assoc. Professor of Neurology

School of Medicine

University of Maryland ;at Baltimore

10 N. Greene St.

Baltimore, MD 21201

ph. 4 1 O-605-7000 x6462

Fax 4 1 o-605-7959



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(would not copy good...tss)

Docket Management Docket: 02N-0273 - Substances Prohibited From Use in

Animal Food or Feed; Animal Proteins Prohibited in Ruminant Feed

Comment Number: EC -10

Accepted - Volume 2


[Docket No. 03-025IFA] FSIS Prohibition of the Use of Specified Risk Materials for Human Food and Requirement for the Disposition of Non-Ambulatory Disabled Cattle

Terry S. Singeltary

Page 1 of 17

Docket No, 04-047-l Regulatory Identification No. (RIN) 091O-AF46 NEW BSE SAFEGUARDS (comment submission)


Docket No. 2003N-0312 Animal Feed Safety System [TSS SUBMISSION]


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