The USDA announced on December 23, 2003 the first diagnosis in the United States of bovine spongiform
encephalopathy (BSE or mad cow disease) in a dairy cow.
BSE is not contagious. It is unlikely that an outbreak of BSE will occur in North American cattle because the
United States and Canada took action in 1997 to prevent transmission via contaminated feed. The risk to human
health from BSE is miniscule. However the diagnosis may seriously affect beef exports from the US.
What is BSE?
Bovine spongiform encephalopathy is a disease of adult cattle affecting the brain and other nerve tissue. It
also is sometimes referred to as mad cow disease. Affected cattle develop progressive behavior changes,
abnormal posture, incoordination, reduced milk production and weight loss. The disease typically occurs in
cattle 5 years of age or older. It is rare for cattle younger than 3 years old to be affected.
The disease was first diagnosed in Great Britain in 1986. It soon became apparent that an outbreak was
occurring in British cattle. The epidemic peaked in 1993 at 1,000 cases per week and has since waned. Currently
about 25 cases per week are identified in the United Kingdom. BSE has now been diagnosed in cattle native to
many other European nations, Japan, Israel, and Canada. The cow diagnosed with BSE in the United States was
imported from Canada as an adult.
What Causes BSE?
BSE is one of a family of similar diseases known as transmissible spongiform encephalopathies (TSE). Different
TSE diseases are known to occur in several species such as sheep, cattle, deer and elk, mink, and man. The
cause of TSE diseases is not known for sure, but a leading theory is that the disease is transmitted by
ingestion of an infectious prion protein.
It is not known how BSE originated. However, it is clear that the outbreak of BSE in Great Britain and Europe
was caused because in the early 1980s cattle were exposed to a common source of feed contaminated with the
infectious prion. Ingestion of contaminated feed products remains the primary risk factor for transmission of
the disease to cattle and the probable mechanism for global spread of the disease. Transmission from animal to
animal is unlikely to occur.
Why has BSE caused such concern?
In 1996 a possible link was proposed between BSE and a fatal disease of humans recently observed in Britain.
The disease is a new TSE in humans called variant Creutzfeldt-Jakob Disease (vCJD). The link between BSE and
vCJD is likely. To date there have been 143 definite or probable cases of vCJD diagnosed in people from the
United Kingdom. The Centers for Disease Control and Prevention believes the current risk to people in the US
from BSE in cattle is extremely low. Even in the United Kingdom, the current risk of acquiring vCJD from
eating beef and beef products is perhaps about one case per 10 billion servings.
BSE is reportable as a foreign animal disease. If you suspect that an animal may have BSE, contact the
USDA/APHIS/VS office (in Nebraska call 402 434-2300) or the Nebraska Department of Agriculture, Bureau of
Animal Industry (402 471-2351).
Regulations are rapidly changing to control transmission of BSE to cattle and to protect public health.
Internet links to the latest on BSE and other important cattle health issues can be found at the UNL Veterinary Extension website.
Summary of recent interim regulations from the US Department of Agriculture
Downer cattle: bans non-ambulatory (downer) animals from the human food supply
Product holding: FSIS inspectors are no longer marking cattle tested for BSE as "inspected and passed"
until confirmation is received that the cattle have, in fact, tested negative for BSE
Specified Risk Material: The skull, brain, trigeminal ganglia, eyes, vertebral column, spinal cord and
dorsal root ganglia of cattle 30 months of age or older and the small intestine of all cattle are specified
risk materials, thus prohibiting their use in the human food supply. Tonsils from all cattle are already
considered inedible and therefore do not enter the food supply.
Advanced Meat Recovery (AMR): AMR is a technology that removes muscle tissue from the bone of beef
carcasses under high pressure without incorporating bone material. FSIS had previously established and enforced
regulations that prohibit spinal cord from being included in products labeled as “meat.” That prohibition now
also includes dorsal root ganglia. Because the vertebral column and skull in cattle 30 months and older will
be considered inedible, they cannot be used for AMR.
Air-Injection stunning: To ensure that portions of the brain are not dislocated into the tissues of the
carcass as a consequence of humanely stunning cattle during the slaughter process, FSIS has banned the practice
of air-injection stunning
Summary of recent interim regulations from the US Food and Drug Administration
FDA will ban from human food, (including dietary supplements) and cosmetics: Any material from "downer"
cattle; any material from "dead" cattle. ("Dead" cattle are cattle that die on the farm (i.e. before reaching
the slaughter plant); Specified Risk Materials (SRMs) that are known to harbor the highest concentrations of
the infectious agent for BSE, such as the brain, skull, eyes, and spinal cord of cattle 30 months or older, and
a portion of the small intestine and tonsils from all cattle, regardless of their age or health; and the
product known as mechanically separated beef (could contain SRMs).
To protect cattle from potential exposure to contaminated feedstuffs FDA will: eliminate the present
exemption in the feed rule that allows mammalian blood and blood products to be fed to other ruminants as a
protein source; ban the use of "poultry litter" as a feed ingredient for ruminant animals; ban the use of
"plate waste" as a feed ingredient for ruminants; and require equipment, facilities or production lines to be
dedicated to non-ruminant animal feeds if they use protein that is prohibited in ruminant feed.
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