Mad Cow Disease : Protecting Blood Supply, Foods and Cosmetics

by Food and Drug Administration (FDA)

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Protecting Foods and Cosmetics

Protecting the food supply from BSE includes ensuring not only the safety of meat, but also of milk and other foods, including dietary supplements, which may contain ingredients from cows.

There is no scientific evidence that milk and dairy products pose any risk for transmitting BSE to humans, and people should not be concerned about consuming milk and milk products, says the FDA's Center for Food Safety and Applied Nutrition.

Other cow-derived foods, such as gelatin, are also protected from BSE through FDA regulations and guidance to manufacturers. And since 1992, the FDA has advised dietary supplement manufacturers and distributors to take steps to ensure that supplement ingredients come from BSE-free herds. The agency also has directed manufacturers of soaps, lipsticks, and other cosmetics that may contain fat or other ingredients from cows to use only ingredients from BSE-free cattle.

Protecting the Blood Supply

Until recently, the possibility of getting the human form of mad cow disease, called variant Creutzfeldt-Jakob disease (vCJD), through tainted blood was only a theory. But in December 2003, authorities in the United Kingdom announced the death of an adult from vCJD whom they believe was infected by a blood transfusion during surgery seven and a half years earlier. The blood had been donated by a young, apparently healthy person in 1996, who died three years later from vCJD.

"We've taken the theoretical risk of blood-borne infection seriously for years, even before the U.K. transfusion case appeared," says David Asher, M.D., head of an FDA laboratory that studies contaminants in blood and tissues. Although there are no rapid, reliable tests to screen the blood supply for vCJD, the FDA has worked with blood centers since 1999 to exclude blood donations by people who lived in the U.K. during a high-risk period for BSE. In 2002, the agency added exclusions of people who might have been exposed to BSE while living elsewhere in Europe.

Protecting Medical Products

Certain cattle parts are used to produce a variety of medical products regulated by the FDA, including some blood products, drugs, devices, vaccines, and human cell- and tissue-based products. For example, some oral medications contain amino acids from cow tissues. Vaccines may be made by growing viruses in cell cultures using a highly diluted cow blood product called fetal bovine serum. And diseased heart valves in people may be replaced with medical devices made from tissues surrounding the heart of a cow.

In regulating these and other medical products, the FDA has advised manufacturers to use cow materials only from BSE-free herds and has recommended that non-animal materials be used in their products whenever possible. Human medical products — whether they're devices or biologics or drugs — have pre-approval requirements, says Lumpkin. When companies come to the FDA for approval, "we work with them on their manufacturing processes, what materials go into the products, and where those materials come from," he says.

The FDA continues to evaluate its regulations and guidances and seeks advice from experts outside the agency to help keep pace with the evolving science relating to transmissible spongiform encephalopathies (TSEs), the family of degenerative diseases of the nervous system that includes BSE and vCJD.

One forum for soliciting independent opinions is the TSE Advisory Committee, a group of scientists and medical experts who met most recently in Silver Spring, Md., in February 2004. In this two-day public meeting, the committee discussed additional measures that the agency might take to further minimize the risk of getting a TSE disease from FDA-regulated medical products. The agency will consider the recommendations of this committee in its regulatory decision-making to keep medical products safe.

Better BSE Science

No one knows for certain what causes BSE, but the leading scientific theory is that an abnormal form of a protein called a prion is responsible. All humans and other mammals have prion proteins in their cells that are harmless in their normal form, but become potentially damaging when they fold into a different shape, clump together, and accumulate in brain tissue. In BSE, abnormal prions are believed to enter the bodies of mammals when they eat tissues contaminated with these prions.

Researchers worldwide are studying how prions cause BSE and other TSEs and how to block the conversion of normal prion protein to the abnormal form, which may lead to methods to prevent or treat these deadly diseases.

Other areas of research focus on developing tests to diagnose TSEs in humans and animals and developing methods to detect the abnormal prions in animal feed and human food. Scientists are trying to find ways to detect BSE in live cattle, since current tests can detect it only by examining brain tissue after death.

Diagnosis of the human form of BSE, vCJD, is also confirmed by looking at brain tissue. In humans, this tissue may be collected through a biopsy while the person is ill or collected after the person has died.

Probable cases can be diagnosed in living people based on their symptoms and the results of either a tonsil biopsy or two non-invasive tests of the brain, electroencephalogram and magnetic resonance imaging. The tonsil biopsy is invasive and requires anesthetizing the patient, says Lawrence Schonberger, M.D., M.P.H., epidemiologist and assistant director of the Centers for Disease Control and Prevention's National Center for Infectious Diseases. "What we're really looking for is a urine or blood test," he says, and research continues to identify less invasive tests.

FDA researchers are developing tests to detect the prohibited proteins in animal feed for cows. These tests will help the agency enforce the feed ban, allowing samples of feed from processing facilities to be checked to ensure that they do not contain the protein that may carry the BSE agent.

FDA scientists are also evaluating decontamination techniques to try to rid TSE agents from surgical instruments, hospital rooms, and other areas where patients and health care workers may be accidentally exposed. Using an evaluation method they developed, FDA scientists have found that conventional decontamination procedures, such as heating with steam augmented by soaking in solutions of lye or using chlorine bleach, "are extremely effective in removing most of the infectivity," says Asher. "This is contrary to the mythology that boiling, heating, or other sterilization doesn't kill the agent," he says. "They don't remove 100 percent of infectivity under worst-case circumstances, but they are successful in removing huge amounts of infective material."

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.