- The decision to render high-risk cow into swine feed
is extremely dangerous. Swine may be infected and asymptomatic for some
time. Some research indicates swine that do not show physical signs of
the prion disease Do show TSE infecton in some research tests.
- On the other hand, we are dealing with semantics here.
The high-risk suspect cow may not have entered the human food chain directly...but
it DID, eventually, as the swine fed the rendered cow were slaughtered
and consumed by humans.
- Patricia Doyle
- BSE SURVEILLANCE - USA (04)
- A ProMED-mail post ProMED-mail is a program of the International
Society for Infectious Diseases
- From Jeffrey L Blair, DVM
May 26, 2004
- (The article cited in the previous posting [20040525.1400]
contained the statement: "The cow in San Angelo was taken a rendering
plant where the Food and Drug Administration (FDA), which regulates rendering
plants, approved it for use in swine feed. Swine are thought not to be
susceptible to mad cow disease." - Mod.TG)
- This newspaper article makes the statement that 'Swine
are not thought to be susceptible to mad cow disease.' I would like to
point out that swine are not likely to become infected with BSE via oral
exposure, but they are susceptible to the agent via parenteral inoculation.
The following study describes this:
- Studies of the transmissibility of the agent of bovine
spongiform encephalopathy to pigs. Gerald A. H. Wells, Stephen A. C. Hawkins,
Anthony R. Austin, Stephen J. Ryder, Stanley H. Done, Robert B. Green,
Ian Dexter, Michael Dawson and Richard H. Kimberlin (http://vir.sgmjournals.org/cgi/content/abstract/84/4/1021)
- "Studies to test the transmissibility of the bovine
spongiform encephalopathy (BSE) agent to pigs began in 1989. Parenteral
inoculation of the agent by 3 routes simultaneously (intracranially, intravenously,
and intraperitoneally) produced disease with an incubation period range
of 69 and 150 weeks. Preclinical pathological changes were detected in
2 pigs killed electively at 105 and 106 weeks post-inoculation.
- Infectivity was detected by bioassay in inbred mice in
the CNS of those pigs that developed spongiform encephalopathy. Infectivity
was also found in the stomach, jejunum, distal ileum, and pancreas of terminally
affected pigs. These findings show that pigs are susceptible to BSE. In
contrast, disease did not occur in pigs retained for 7 years after exposure
by feeding BSE-affected brain on 3 separate days, at 1- and 2-week intervals.
The amounts fed each day were equivalent to the maximum daily intake of
meat and bone meal in rations for pigs aged 8 weeks. No infectivity was
found in tissues assayed from the pigs exposed orally. This included tissues
of the alimentary tract. It is suggested that these pigs did not become
infected. The relatively high oral exposure used in these experiments compared
with feed-borne exposure in the field may explain the absence of an epidemic
of spongiform encephalopathy in domestic pigs concurrent with the BSE
epidemic in the UK."
- According to Matthews (cited below), the report of the
1st pig shown to be infected with BSE in the above study led to immediate
changes in rules in the UK to exclude specified risk materials from the
food of all domestic livestock and pets.
- The potential for transmissible spongiform encephalopathies
in non-ruminant livestock and fish D. Matthews & B.C. Cooke. Rev.
sci. tech. Off. int. Epiz., 2003, 22 (1), 283-296
- While the questionable cow in San Angelo may have been
approved for use in swine feed, I would hazard a guess that this was after
specified risk material (brain, spinal cord, tonsil, thymus, spleen, and
intestine) were removed. I have no first-hand knowledge of the case, however.
- Jeff Blair, DVM Post Doctoral Fellow Department of Pathobiology
162 McElroy Hall College of Veterinary Medicine Oklahoma State University
Stillwater, OK 74078 405-744-1182 <firstname.lastname@example.org>
- [BSE can be experimentally produced in cattle -- and
in this case in swine -- by inoculating infected material into the brain,
the peritoneal cavity, and by intravenous injection. Swine develop a spongiform
encephalopathy from this type of agent introduction. However, swine fed
the infected material did not develop the clinical signs of the disease,
but on assay their tissues indicated the possibility of a prion disease.
Therefore, specified risk material was excluded from all animal and pet
feeds in the UK as a result of this experiment.
- The cow in San Angelo, Texas, did not enter the human
food chain. However, the decision to incorporate the products into swine
feed may not have been scientifically justified.
- Perhaps these studies will prompt FDA and USDA to re-evaluate
current rules. - Mod.TG]
- Patricia A. Doyle, PhD Please visit my "Emerging
Diseases" message board at: http://www.clickitnews.com/ubbthreads/postlist.php?Cat=&Board=emergingdiseases
Zhan le Devlesa tai sastimasa Go with God and in Good Health