Americans eat about 65 pounds of beef every year. As federal investigators try to determine how a cow in Washington state may have become infected with the brain-wasting illness, mad cow disease (search), some consumers are wondering if they need to take any precautions and change their diets.

Q: Why is mad cow disease a concern?

A: A human disease related to mad cow is known as variant Creutzfeldt-Jakob disease (search). It is incurable and was blamed for 143 deaths in Britain, which suffered a mad cow disease outbreak in the 1980s.

Humans can get it by eating meat that contains tissue from infected animals, specifically from the brain and spinal cord.

Q: Is it likely I will get sick from eating beef?

A: Mad cow disease, officially known as bovine spongiform encephalopathy, has not been found in beef muscle or dairy products. Scientists say the disease is found only in nerve tissue, specifically the brain and spinal cord. So experts say beef steaks and roasts are safe, along with hamburger ground from labeled cuts, such as chuck or round.

Meat such as the liver and tongue also are safe.

Q: Are processed beef products riskier to eat?

A: Slightly. Meat such as ground beef, hot dogs, taco meat, and luncheon meats are made from several sources of meat. They are obtained by machines, known as advanced meat recovery systems, that strip flesh from the spines and other awkwardly shaped parts of the cow. Some tests have detected tissue from the central nervous system in samples of beef products. However, many meat companies remove the spine and brain before processing.

Such tissues are not supposed to be in meat products in the United States unless they are labeled. Industry officials say Agriculture Department tests on beef products found incidental amounts of central nervous system cells.

Q: How can the government ensure that beef is safe?

A: In the case of the cow in Washington, federal and state officials have quarantined the herd on the farm where the animal came from. If tests in England confirm that the cow had BSE, then the herd will be slaughtered to prevent an outbreak. Investigators also are tracing where the meat from the animal was sent.

Beef and cattle imported from countries with BSE are banned. Also, the government has banned since 1997 cattle feed made with protein or bone meal from being fed to other grazing animals — cattle, goats and sheep. Farmers used to feed such meal to their animals because it helped them gain weight.

Consumer groups argue there are too many loopholes in the system, though. They have demanded wider testing and better tracking of sick animals.

Q: The cow was a "downer" animal that was injured when giving birth. Why are these animals allowed into the food supply?

A: The Agriculture Department allows such animals into the food supply if they are not sick. Federal veterinarians check the animals for signs of illness before they are processed. If an animal is sick, it isn't allowed to be slaughtered for meat and tests are run to determine what ails it.

Often, downer animals are processed for pet food because their meat is rendered, a process that basically cooks the meat and kills disease.

Q: Can my pets get sick with mad cow?

A: Mad cow disease is one of a family of illnesses that has only been known to infect animals such as cattle, sheep, elk and deer.

The cow likely was sick from eating feed made from an infected cow, even though that type of feed is banned. If that's true, other cattle also might be infected and they might have been processed into food for humans by accident. Or they might have been ground into animal feed that could infect other livestock that people could someday eat.

The Food and Drug Administration (search) is working with the Agriculture Department to determine the source of the illness.