The US Department of Agriculture (USDA), one of the federal agencies responsible for the safety of certain meat and poultry products, as well as animal health, maintains the risk to human health that might stem from eating BSE-infected animals is extremely low in the United States. This is due in large part to the programs they have had in place for several years to detect the presence of BSE, to prevent the spread of the disease through the cattle population, and to reduce the likelihood that animal products harboring the infectious agent make their way into the human food supply. More information about these regulatory programs, which also involve the U.S. Food and Drug Administration, is provided on the Federal Initiatives

As BSE is the bovine (affecting cattle) form of a transmissible spongiform encephalopathy (TSE), there also are several TSEs expressed in humans: Creutzfeldt-Jakob disease (CJD), variant-CJD (vCJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), fatal familial insomnia (FFI) and Kuru. Since 1996, strong evidence has accumulated for a causal relationship between outbreaks of BSE in cattle and the variant Creutzfeldt-Jakob disease (vCJD). Both disorders are invariably fatal brain diseases with unusually long incubation periods measured in years and are caused by an unconventional transmissible agent (neither virus nor bacteria). The US Centers of Disease Control (CDC) provides comparison of the naturally occurring CJD and the BSE-induced vCJD on its website, though it is important to note that these two diseases ARE NOT the same and that classical CJD has not linked to consumption of beef.

Since variant CJD was first reported in 1996, a total of 221 patients with this disease from 11 countries have been identified. As of October 2009, variant CJD cases have been reported from the following countries: United Kingdom, France, Ireland, the United States, Spain, the Netherlands, Portugal, Canada, Italy, Japan, and Saudi Arabia. Two of the three U.S. cases, two of the four cases from Ireland, and the single cases from Canada and Japan were likely exposed to the BSE agent while residing in the United Kingdom. One of the 23 French cases may also have been infected in the United Kingdom. There has never been a case of vCJD that did not have a history of exposure within a country where this cattle disease, BSE, was occurring.

It is believed that people who have developed vCJD became infected by consuming cattle products contaminated with the BSE agent. Research has shown that the agent accumulates in specific tissues: brain, spinal cord, retina, dorsal root ganglia (nervous tissue located near the backbone), distal ileum (part of the small intestine) and the bone marrow. Thus, muscle meat (steaks and hamburger) from infected animals are believed to be safe for human consumption. Still, an animal suspected of being infected with BSE is prohibited from entering the human food supply. The BSE agent has not been detected in blood, milk or dairy products.

Systems that protect public health and the beef industry

When the first native-born North American case of BSE was diagnosed in Canada in May of 2003, the United States closed its northern border to cattle and beef products; cattlemen, dairymen and others directly involved with the cattle industry took an interest. US consumers became more interested in December 2003 when BSE was discovered in a Holstein that had been slaughtered in Lake Moses, Washington. BSE was discovered in this cow because of an existing BSE surveillance program in which suspect animals (including downer cattle) were tested for presence of the prion agent. By the time tests confirmed presence of BSE, the affected dairy cow’s meat had entered the food supply, its risk materials (e.g. brain, spinal cord) had been rendered, and meat products distributed. The discovery led to public awareness of the systems and programs that have long been serving to protect both public health and agricultural industries from foreign animal disease.

While a number of cases (18 in Canada and three in the U.S) have been found in North America since 1993 and confirm that BSE is present, the actual number of infected animals present in the cattle population is believed to be extremely low. The United States and Canada have conducted surveillance for BSE since 1992 at rates that have met or exceeded international standards. There is no doubt that the steadily increasing intensity of surveillance has contributed to the probability of finding a case of BSE.

Information in this section came from the following sources:
Centers for Disease Control