Mad Cow Disease Revisited: Now That It's Here, What Do We Do?
What Are the Facts About BSE in the US?
Most cattle contract mad cow disease by eating feed made from infected beef byproducts. When this happens, a modified form of a protein, called a prion, becomes infectious and accumulates in the brain and spinal tissues of the cow, causing this fatal, neurological disease. Unfortunately, we have no effective treatments against prions. They are resistant to both heat and antibiotics, weapons we count on to protect us against bacteria or viruses.
The first BSE-infected cow in the US was found in Washington State and came from a dairy farm in Alberta, Canada. A total of 81 cows were sent to the US from this farm in 2001. The USDA investigated and isolated 25 of these animals because they were born within a year of the infected cow and may have shared the same feed. In March 2006, a BSE-infected cow was found in Alabama. The rest of the herd was tested and found to be negative.
What Has the US Done to Prevent the Spread of Mad Cow Disease?
Since December 2003, the USDA’s Food Safety and Inspection Service (FSIS) has taken several precautions to help prevent the spread of Mad Cow disease in the US. These include:
- A ban prohibiting “downer” cattle (cattle too sick to walk, signaling a possible BSE infection) from entering the food chain.
- A ban on the cattle parts most likely to be infected (the skull, brain, eyes, and spinal cord of cattle over 30 months of age as well as the small intestines of cattle of all ages) from entering the food chain.
- A ban on the practice of air-injection stunning. This technique humanely stuns cattle before slaughtering, but may cause portions of infected brain tissue to enter other nearby, edible tissue.
- A change in BSE-testing procedures, requiring final test results before meat can be certified as USDA-inspected.
- Restrictions on techniques to mechanically remove meat from bones (advanced meat recovery).
FDA has also implemented new regulations, including:
- A ban on the use of blood in feed for cattle and other grazing animals, including sheep and goats.
- A ban on the use of poultry litter and leftover meat from restaurants in cattle feed. Cosmetics and dietary supplements are banned from containing materials from cattle too sick or hurt to walk.
- A requirement for factories to have separate lines for bovine feed and feed for other animals to guard against accidental cross-contamination.
Will Mad Cow Disease Spread Within the US?
Studies conducted by the Harvard Center for Risk Analysis in 2001 and 2003 showed that the likelihood of mad cow disease spreading extensively in the US would be very low, even if infected animals entered the American agriculture system from Canada. The researchers concluded that “if these imports did introduce BSE into the US, measures taken by the government and industry since 1997 will have arrested the disease and begun to eradicate it.”
In February 2004, a scientific panel appointed by the USDA to recommend actions to combat the spread of mad cow disease stated there is a high probability of more cases of mad cow disease in American cattle and that infected cattle byproducts have likely already entered US cattle feed.
However, because of stringent controls already in place, both the Harvard researchers and the more recent scientific panel of experts suggest that an outbreak of more cases of mad cow would not be widespread.
Nevertheless, the scientific panel recommended the US government ban all barnyard animal remains from cattle food as a precaution, and ban cattle brains and spinal material in animal feed and pet food. The panel also recommended an aggressive monitoring program to test all high-risk animals older than 30 months of age for BSE. The USDA is currently considering the recommendations carefully before taking any further actions.
What Are the Risks to the Average Consumer?
In humans, the Centers for Disease Control and Prevention (CDC) reports that the risk to humans in the United States is “extremely low.”
The USDA concurs. Dr. Ron DeHaven, Deputy Administrator of Veterinary Services for USDA's APHIS stated, "We feel confident that the remaining animals represent very little risk."
So, what steps, if any, should you take to reduce your risk of exposure to BSE? First, if you choose to eat beef, know where it comes from. Small producers who feed their animals vegetarian feed sell beef that bears an organic label. Aside from not eating beef at all, animals fed vegetarian feed would pose the least risk of all cattle. Also kosher beef might be safer than non-kosher beef because the animals are slaughtered in ways that do not cause brain tissue to be spread through the blood stream.
Second, choose cuts of meat that are less likely to be infected with BSE. Avoid meat cut from spinal bone, such as porterhouse or T-bone steaks, as they have a greater chance of coming into contact with spinal cord tissue. Chopped or processed meats may also be more risky because they may include meats separated by machines that could have mixed infected tissues with edible tissues. Instead, choose shanks or brisket, which are less likely to be infected.
Centers for Disease Control and Prevention
United States Department of Agriculture
United States Food and Drug Administration
BC Health Guide
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Centers for Disease Control and Prevention. Questions and answers regarding Bovine Spongiform Encephalopathy (BSE) and Creutzfeldt-Jakob Disease (CJD). Available at: http://www.cdc.gov/ncidod/diseases/cjd/bse_cjd_qa.htm. Accessed January 20, 2004.
Cohen J, et al. Evaluation of the potential for Bovine Spongiform Encephalopathy in the US. Harvard Center for Risk Analysis. Harvard School of Public Health website. November 26, 2001; Revised October, 2003. Available at: http://www.hcra.harvard.edu/pdf/madcow.pdf. Accessed February 5, 2004.
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United States Food and Drug Administration. Center for Food Safety and Applied Nutrition. Commonly asked questions about BSE in products regulated by FDA’s Center for Food Safety and Applied Nutrition (CFSAN)—January 14, 2004. Available at: http://www.cfsan.fda.gov/~comm/bsefaq.html. Accessed February 6, 2004.
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Last reviewed June 2008 by David L. Horn, MD, FACP
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