Bovine Spongiform Encephalopathy (BSE) or "mad cow disease", is
a transmissible, neurodegenerative, fatal brain disease of cattle. BSE is one
kind of transmissible spongiform encephalopathy (TSE). Although the brain is
the main organ affected, other infected tissue can include the spinal cord,
the lymphatic system (spleen, thymus, tonsils, lymph nodes), the intestines,
and the eyes.
TSE's include the following diseases: BSE in cattle; scrapie in sheep and goats;
transmissible mink encephalopathy; feline spongiform encephalopathy in cats;
chronic wasting disease in mule deer and elk; and Creutzfeldt-Jakob disease
(CJD), kuru, Gerstmann-Straussler syndrome, and fatal familial insomnia in humans.
In the United States, there have been reported cases of scrapie, transmissible
mink encephalopathy, wasting disease in mule deer and elk, and CJD. There have
been no diagnosed cases of BSE in the United States. Scrapies has been around
for over 200 years. There is no evidence that people can contract scrapies from
eating infected lamb or mutton.
Where is BSE?
BSE is a new TSE that first appeared in British cattle in the mid-1980's. The
disease has a long incubation period of four to five years, but ultimately is
fatal to cattle within weeks to months once they begin to show symptoms. Currently
there is no test to detect BSE in live animals; it can only be diagnosed by
examining brain tissue under a microscope. From November 1986, when the first
case was diagnosed in Britain, until December 2000, approximately 180,000 cases
of BSE were confirmed in the UK. A relatively small number of cases (a total
of approximately 1,300) have been reported outside of the UK in Belgium, Denmark,
France, Ireland, Liechtenstein, Luxemburg, Netherlands, Portugal, and Switzerland.
Germany and Spain reported their first native cases in November 2000. A few
cases have been reported in Canada, the Falkland Islands, Italy and Oman, but
solely in animals imported from the UK.
Where did BSE come from?
BSE in Britain may have been caused by feeding cattle rendered protein produced
from the carcasses of scrapie-infected sheep or cattle with a previously unidentified
TSE. The practice of using products such as meat-and-bone meal as a source of
protein in cattle rations has been common for several decades. There is no evidence
that BSE spreads horizontally, i.e. by contact between adult cattle or from
cattle to other species. It is only spread through consumption of infected protein
products.
What is the US doing to prevent it here?
"Mad cow disease" has not been diagnosed in the United States, and
USDA has worked proactively to keep it that way. Stringent measures have been
put into place to address prevention, education, surveillance, and to respond
to issues and concerns related to BSE.
In 1989, the US imposed a mandatory ban on live cattle imports from Britain
and other BSE-affected countries (BSE in their domestic herds). At the same
time, we restricted beef imports from Britain and other BSE-affected countries.
According to USDA's Food Safety and Inspection Service (FSIS), no British beef
has been imported into the US since 1985. Other products derived from ruminants
are also prohibited from entry, except under special conditions or under USDA
permit for scientific or research purposes.
In December 1997, these restrictions were extended to include all of the countries
of Europe due to concerns about widespread risk factors and inadequate surveillance
for BSE. In addition, all imports of rendered animal protein products, regardless
of species, from Europe are prohibited. This restriction applies to products
originating, rendered, processed or otherwise associated with European products.
USDA is taking this emergency action to prevent potentially cross-contaminated
products from entering the United States.
Also in 1997, the Food and Drug Administration imposed a regulation prohibiting
the use of most mammalian protein in the manufacture of animal feeds given to
ruminants. This regulation also requires process and control systems to ensure
that ruminant feed does not contain the prohibited mammalian tissue.
Veterinarians, laboratory diagnosticians, industry, and producers are continuously
educated and informed of the clinical signs and pathology of BSE. The USDA also
has a very stringent surveillance program in place through which any animal
suspected of, or showing symptoms similar to those of BSE are immediately tested.
As of December 2000, nearly 12,000 brains from the US and Puerto Rico have been
examined with no evidence of BSE or other TSE detected.
An emergency response plan to be used in the event that BSE is identified in
the US is in place, and prevention and diagnostic measures are constantly revised
and adjusted as new information and knowledge about TSE's are learned.
For additional information on BSE in cattle, contact:
-- your veterinarian
-- Cornell Cooperative Extension at (315) 736-3394
-- USDA, APHIS, Veterinary Services at (609) 259-5825
-- Or the APHIS web site at www.aphis.usda.gov
For public health information, contact CDC at (404) 639-3091. For food safety
information, contact FSIS at (202) 205-0293 or call the USDA's Meat and Poultry
Hotline at (800) 535-4555. For more information about the ruminant feed ban,
call FDA's Consumer Hotline at (800) 532-4440.