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From: TSS ()
Subject: PRO/AH> BSE policy - USA: change considered (02)
Date: April 20, 2005 at 10:46 am PST

-------- Original Message --------
Subject: PRO/AH> BSE policy - USA: change considered (02)
Date: Wed, 20 Apr 2005 10:21:26 -0400 (EDT)
From: ProMED-mail
Reply-To: promedNOREPLY@promed.isid.harvard.edu
To: promed-ahead@promedmail.org


BSE POLICY - USA: CHANGE CONSIDERED (02)
*******************************************
A ProMED-maili post

ProMED-mail, a program of the
International Society for Infectious Diseases


[1]
Date: 18 Apr 2005
From: Terry S Singeltary Sr


An excellent commentary by Mod.TG et al.

I would kindly like to add that "subclinical TSE" [see: BSE, possible
subclinical infection (02) 20000901.1466 for reference and discussion], and
a downer that may have fallen and broken a leg, hip etc, due to the first
symptoms of a TSE, however far-fetched this may be, it is very possible,
and any cow going into the food chain, whether for animals or humans, is
one too many.

So, any relaxing of this downer ban is just not acceptable, unless -- as
Mod.TG points out -- 100 per cent testing with the most sensitive testing
to date, that is, western blot with the addition of phosphotungstic acid
precipitation step (Bio-Rad Deslys et al.) and/or the CDI Prusiner and
colleagues are boasting about.

However, even 100 per cent BSE/TSE testing will only be as good as the
tests being used, and the ones doing the testing. You have to want to find it.

--
Terry Singletary


******
[2]
Date: 19 Apr 2005
From: Carol J Marcus-Sekura


Thank you for that informative discussion. I have a short comment about
animal feed: the US may not put downer cattle into pet food, but we do put
it into non-ruminant animal feed. Farmers are instructed not to feed it to
ruminants. This seems a risky approach, as mistakes will be made; some
staff may not know or understand the word ruminant, and smaller farms may
not want to purchase many types of feed.

A change in this policy to conform to international policies was
recommended by international groups after the US BSE incident, but to my
knowledge, it was not adopted by the US.

--
Carol J Marcus-Sekura, PhD
BASI
7413 Ottenbrook Terrace
Rockville, MD 20855


******
[3]
Date: 19 Apr 2005
From: Bill Hall


I note with considerable interest the posting concerning the proposed
changes in the US position on BSE, in particular the comment on the
reporting of BSE/TSE findings in the brains of market-age pigs.

Were you referring to the paper listed below (1), which reported lesions
induced by inoculation? If not, can you give the citation to the material
referred to?

"As to the concerns in the article that a ban on downer animals could be
extended to swine, perhaps it should. In a recent study of swine,
spongiform encephalopathy changes were noted in the brains of market swine,
despite the absence of any outward signs of clinical neurological disease."

1. Studies of the transmissibility of the agent of bovine spongiform
encephalopathy to pigs. J Gen Virol 2003; 84(Pt4): 1021-31. PMID: 12655106

--
William Hall BVSc MS
Manager, Research and Innovation Division
Australian Pork


******
[4]
Date: 19 Apr 2005
From: LuAnn McKinney


Great discussion between the 2 moderators... thank you!
I know that intracerebral injection will cause a 'Porcine' SE, but could
you please give us the reference for the "recent study of swine, spongiform
encephalopathy changes were noted in the brains of market swine, despite
the absence of any outward signs of clinical neurological disease." I've
missed that one and it's really, really important.

--
L McKinney, DVM, DACVP.


******
[5]
Date: 19 Apr 2005
From: Richard Llewellyn Brown


1. It would be worth finding out where the temptations to cut corners are
both in terms of numbers and type of conditions. So, for instance, if the
majority of cases are young animals with a clear cut bona fide recent
fracture, which everyone can see then one should cater for this. Just to
ban that beast is producing too much temptation: it looks edible!.To be on
the safe side you could hold the carcase in the freezer and not release
until a check of the CNS with a rapid technique has passed it. The producer
to pay some of the test costs.

2. If, however, a significant number are downer cows of 29 months and 29
days old then I would be very careful. We have found a quite a number of
downers which look pretty clear cut cases of paralysis, bright alert at the
head etc, they are in fact BSE. Admittedly these are older cattle.

3. Then you get the "from the blind side case". We even had one case (not
that it was going to slaughter) of an old cow with gangrenous mastitis
going off her legs. We thought she had paresis due to toxaemia but she also
had BSE. Surprise all round. Cross questioning of the farmer revealed a
slight hindleg lameness weakness which cured itself the year before. (If
she had been transported then ,what would have happened!) She had been a
lively character: otherwise little to note.

4. So I agree with the moderators there is a balance which neeeds to be
explained but I do suggest you look at the real life temptations which you
can only know if you know the types of cases you are dealing with and their
frequency.

Personally I would go for under 24 months, clear cut fracture, with vet
certificate and producer paid CNS testing :-OK to eat. All the rest no: too
open to abuse.

--
Richard Llewellyn Brown MRCVS
Huntly
Aberdeenshire
Scotland

******
[6]
Date: 19 Apr 2005
From: J Herrmann


A number of issues are worth mentioning here:
1) It is true that almost all "downer" cattle are not infected with BSE.
However, they traditionally carry a higher level of contamination with
zoonotic bacteria and often are more at risk for carrying anitbiotic
residues than are "walkers".

2) Cattle usually do not show symptoms of BSE until over 30 months of age
(the average age for BSE (+) cattle in the EU during 2003 was somewhere
around 55 months if I remember correctly).

3) The analytic sensitivity of our current tests, including
immunohistochemistry, ELISA and Western Blot, is such that adequate amounts
of abnormal prions usually do not accumulate until about 6 months prior to
clinical symptoms. Therefore there is a built in age limitation on the
sensitivity of current tests.

4) Given the age limitation of current tests methods, it is difficult to
justify testing the vast majority of US cattle that are processed each
year; about 85 per cent of the 30 million slaughtered each year are less
than 30 months of age.

5) USDA has focused on BSE testing cattle that may have clinical symptoms
of BSE despite the fact that symptoms are not pathognomonic for BSE. All 4
cows that were recently positive in North America (3 Canadian, one US) were
not specifically symptomatic for BSE.

6) USDA has made no concerted effort to survey the cattle that were born
before the ruminant feed restrictions of 1997-1998 and that could have had
direct exposure to contaminated meat and bone meal. Approximately 1-2
million of these cattle are slaughtered each year.

--
J Herrmann, DVM, MPH, DACT
University of Illinois
Former Congressional Science Fellow, United States Senate

--
ProMED-mail


[Regarding silent BSE, there remains more emotional hype about this disease
than there is solid evidence. However, the article in the footnote is
interesting and, although several years old, it is worth a read.

Title 21 of the Code of Federal Regulations part 589.2000 reads,
"(a)Protein derived from mammalian tissues means any protein containing
portion of mammalian animals, excluding: Blood and blood products; gelatin;
inspected meat products which have been cooked and offered for human food
and further heat processed (such as plate waste and used cellulosic food
casings); milk products whose only mammalian protein consists entirely of
porcine or equine products."

21 CFR 589.2000 continues: "(4) Feed manufacturer includes manufacturers of
complete and intermediate feeds intended for animals, and includes on-farm
in addition to off-farm feed manufacturing and mixing operations."

There are published newspaper accounts of farm mixing of pet food by
products being fed to cattle. According to the published accounts, the
paperwork from the pet food company, signed by the animal producers, stated
that it would not be fed to any ruminant animal such as cattle, goats, or
sheep. Tests confirmed ruminant DNA in the feed bunkers where cattle were
feeding. However, the article reported that, since the FDA could not
demonstrate a prion to a court of law that they would take no action
regarding on-farm mixing.

The newspaper accounts indicate that the FDA is not standing up to its own
published rules. One reason may be that they don't know what to do with a
group of cattle under 30 months old in a feedlot-type situation that have
been fed banned product. FDA is not usually in the habit of indemnifying
animals. That task usually is under the purview of the USDA. However, the
feed ban rule is an FDA rule, so why should USDA indemnify an owner when
they don't even have a rule to cover the circumstances?

If accounts such as these are published in newspapers, then the second
article in today's posting would be correct -- that we are not protected
from BSE by the feed ban.

As to postings 3 and 4, regarding my comment about swine: after multiple
relocations in a short time, it is difficult to put my hand on the article
upon which I based that statement. However, here are a couple of likely
candidates for that comment:

1) Studies of the transmissibility of the agent of bovine spongiform
encephalopathy to pigs. Gerald AH Wells, Stephen AC Hawkins, Anthony R
Austin, Stephen J Ryder, Stanley H Done, Robert B Green, et al:

2) The potential for transmissible spongiform encephalopathies in
non-ruminant livestock and fish. D Matthews, BC Cooke. Rev Sci Tech OIE
2003; 22(1): 283-96.
3) The neuropathology of experimental bovine spongiform encephalopathy in
the pig. Ryder SJ, Hawkins SA, Dawson M, Wells GA. J Comp Pathol 2000;
122(2-3): 131-43.

However, without regard to any of these, the report from a new study is
worth your time to read. It details transplanting swine organs to people
and the possibility of TSE disease being transmitted.

Research Project: Transmission, Differentiation, and Pathobiology of
Transmissible Spongiform Encephalopathies


National Animal Disease Center Virus and Prion Diseases of Livestock


Evaluation of a diet free of animal protein in germfree swine. Loynachan A,
Pettigrew J, Wiseman B, Kunkle R, Harris D. Xenotransplantation 2005; 12:
149-55. - Mod.TG]

[see also:
BSE policy - USA: change considered: 20050418.1094]

.......................tg/pg/sh


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