From: Terry S. Singeltary Sr. (216-119-144-9.ipset24.wt.net)
Subject: ARS Battles Mad Cow, Scrapie, and Other TSEs
Date: January 1, 2005 at 2:37 pm PST
-------- Original Message --------
Subject: ARS Battles Mad Cow, Scrapie, and Other TSEs
Date: Sat, 1 Jan 2005 16:30:59 -0600
From: "Terry S. Singeltary Sr."
Reply-To: Bovine Spongiform Encephalopathy
##################### Bovine Spongiform Encephalopathy #####################
2 Agricultural Research/December 2004
Long before mad cow disease began making news in Great
Britain, ARS was a leader in research to safeguard livestock
from this and other transmissible spongiform encephalopathies
(TSEs), a group of diseases caused by abnormal proteins in the
nervous system called prions. But there’s no question that more
attention has been focused on the topic since the first case of
mad cow was diagnosed in the United States last December.
Technically referred to as bovine spongiform encephalopathy
(BSE), mad cow disease is one of four known animal TSEs,
and it poses a serious threat to the U.S. cattle industry. That
first U.S. case resulted in a complete shutdown of cattle exports
to several countries. The Japanese market was still closed when
this issue went to press, despite the fact that the positive cow
was of Canadian origin. The cost of such losses is staggering,
as demonstrated by the 1986 outbreak of BSE in the United
Kingdom, which at last report has cost European countries an
estimated $107 billion.
The USDA Animal and Plant Health Inspection Service’s
(APHIS) National Veterinary Services Laboratory (NVSL)
confirmed the first U.S. BSE case. APHIS called on ARS’s
National Animal Disease Center in Ames, Iowa, to conduct
confirmatory tests on the tissue samples and asked ARS’s U.S.
Meat Animal Research Center in Clay Center, Nebraska, to
coordinate DNA testing and analysis to help trace the origin of
the BSE-positive cow.
BSE is also a potential human health safety problem because
laboratory animals and cows have become infected after
eating specified risk materials, such as brain or spinal cord,
from infected cows.
To safeguard livestock and people, the U.S. Department of
Agriculture has maintained an aggressive import exclusion and
surveillance program, coupled with steps to eliminate recycling
of ruminant byproducts through the mammalian food chain,
which is how BSE is transmitted from cow to cow.
The full impact of TSEs in the United States and around the
world has yet to be determined. But the need for solid scientific
information about transmission and pathology of prion-related
diseases is critical. Many questions remain, including the actual
cause and mechanisms of disease, why some TSEs are
infectious while others are not, and why certain animal species
are susceptible to some strains while others are resistant.
Much of the ARS research on TSEs will go to provide support
for the agencies that must directly respond to the issue, in
this case APHIS-NVSL and USDA’s Food Safety and Inspection
Service. The regulations and policies these agencies write
to deal with TSEs can only be as good and as focused as the
scientific information on which they are based.
ARS already has a special depth of expertise in prion-related
research. The agency developed the test used by APHIS-NVSL
to identify the first BSE case. From its work on scrapie, the
TSE that mainly afflicts sheep, ARS developed the first practical
live-animal test for scrapie as well as techniques for identifying
preclinical infected sheep over age 18 months at slaughter. This
technology has been transferred to APHIS, and the antibodies
are commercially available.
There is a vital need for better diagnostic tests for BSE and
other TSEs, especially sensitive and reliable live-animal tests
that can pick up abnormal prions before onset of clinical signs.
ARS scientists are working on ultra-sensitive detection assays
that can be applied to food, diagnostic samples, or the environment
to learn more about the epidemiology and biology of TSEs.
ARS is also researching the evolution of new and emerging
TSE strains and evaluating transmissibility among different
species. There’s a critical need for innovative methods of rapid
strain typing to differentiate various TSEs. ARS already has
the only TSE-dedicated biocontainment facility in the United
States, which allows long-term research on the large animals
most affected by these diseases—cattle, deer, and elk. Other
laboratories depend on mice studies because they’re unable to
house livestock or wildlife for the long incubation needed.
Our expanding TSE research program integrates teams of
veterinary clinicians, pathologists, protein chemists, and TSE
specialists in a national, coordinated effort in pathobiology,
diagnostic discovery, and intervention. Success in any of these
areas will speed progress of the entire research program.
ARS is also working with scientists at the Institutes of Animal
Health in Compton, England, and Edinburgh, Scotland,
and the Veterinary Laboratories Agency in Weybridge, England,
where BSE pathobiology studies have been occurring for years.
And we’re collaborating with the University of Santiago,
Spain, to study ways to differentiate normal prion proteins from
abnormal ones; the University of California-San Francisco to
improve current antibody-based diagnostic methods; the
University of Washington to breed mice that are more
susceptible to chronic wasting disease, the TSE now spreading
in U.S. deer and elk; and Colorado State University to develop
a prototype diagnostic test for preclinical infected free-ranging
deer. The test is currently being used in surveillance efforts,
and it’s being adapted to a 1-day assay.
USDA remains confident in the safety of the U.S. food supply.
With elimination of specific risk materials from the food
chain and an active surveillance program, the risk to human
health from BSE is extremely low. But ARS continues to pursue
significant scientific knowledge and research that will be
vital to the control and eradication of TSEs as an agricultural
and public health threat.
Cyril G. Gay
ARS National Program Leader
Veterinary Medical Science, Animal Health and Safety
ARS Battles Mad Cow, Scrapie, and Other TSEs
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