Alabama Cow Has Mad Cow Disease
Cow Never Entered the Animal or Human Food Chains, U.S. Official Says
WebMD News Archive
What Causes Mad Cow Disease?
BSE is a transmissible, slowly progressive, degenerative, and fatal disease
affecting the central nervous system of adult cattle. It was first reported
among cattle in the U.K. in 1986. Researchers believe that the infectious agent
that causes mad cow disease is an abnormal version of a protein called a prion.
For reasons still unknown, this protein becomes altered and destroys nervous
system tissue -- the brain and spinal cord.
Cooking has not been shown to kill the BSE agent, according to information
posted on the USDA's web site. Common methods to eliminate disease-causing
organisms in food, like heat, do not affect prions.
There is no evidence to suggest that milk and dairy products carry the agent
that causes BSE, states the USDA. Prions only seem to live in nervous system
Does Mad Cow Disease Affect Humans?
A human version of mad cow disease called variant Creutzfeldt-Jakob disease
(vCJD) is believed to be caused by eating beef products contaminated with
central nervous system tissue, such as brain and spinal cord, from cattle
infected with mad cow disease.
For this reason, the USDA requires that all brain and spinal cord materials
be removed from high-risk cattle -- older cattle, animals that are unable to
walk, and any animal that shows any signs of a neurological problem. These cow
products do not enter the U.S. food supply. The USDA believes this practice
effectively safeguards U.S. public health from vCJD.
How Is vCJD Diagnosed?
All age groups can be affected by vCJD, which is very hard to diagnose until
it has nearly run its course.
In its early stages, people have symptoms related to the nervous system,
like depression and loss of coordination. Later in the illness, dementia
develops. But only in advanced stages of the disease can brain abnormalities be
detected by MRI (magnetic resonance imaging); vCJD is fatal, usually within 13
months of the onset of symptoms.
It is extremely unlikely that anyone would get vCJD from eating food
purchased in the U.S. To prevent mad cow disease from entering the country,
since 1989 the federal government has prohibited the importation of certain
types of live animals from countries where mad cow disease is known to