Mad Cow Disease: Know the Basics. Here's what you need to know about mad cow disease
What is mad cow disease?
What is mad cow disease?
Mad cow disease, or bovine spongiform encephalopathy (BSE), is a
transmissible, slowly progressive, degenerative, and fatal disease affecting
the central nervous system of adult cattle. The USDA tests some 20,000
animals every year for this disease.
Researchers believe that the infectious agent that causes mad cow disease is
a protein normally found on cell surfaces, called a prion. For reasons still
unknown, this protein becomes altered to become disease producing.
Does cooking food kill the prion that causes mad cow disease?
Common methods to eliminate disease-causing organisms in food, like heat, do
not affect prions. Also, prions only seem to live in nervous system tissue.
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 nerve tissue, such as brain and
spinal cord, from cattle infected with mad cow disease. For this reason, the
USDA requires that all nervous system materials be removed from cattle that are
unable to walk -- an indication that there may be 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.
According to the CDC, no cases of vCJD have been identified in the U.S.
Having said that, it is important to clarify the differences between variant
CJD and another form of the disease, referred to as classic CJD. Classic CJD
occurs each year at a rate of 1 to 2 cases per 1 million people throughout the
world, including in the U.S. and other countries where mad cow disease has
never occurred. It is not linked to the consumption of nerve tissue from mad
cow disease-affected cattle -- both vegetarians and meat eaters have died from
What are the symptoms of vCJD?
The disease affects all age groups and 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 dementia and jerking muscle movements. But only in
advanced stages of the disease can brain abnormalities be detected by X-ray or
MRI (magnetic resonance imaging).
Is it possible to get vCJD from eating food purchased in the
It is extremely unlikely that this would happen. 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 exist. This ban includes meat products used in human,
animal, and pet foods.
Can you get vCJD from drinking milk from an infected cow?
Milk and milk products are not believed to pose any risk for transmitting
mad cow disease to humans. Experiments have shown that milk from mad
cow-infected cows has not caused infections.