Human Infection from "Mad
Cow Disease" in the U.S.?:
A Precautionary Ban on Blood Donations
By S. Van McCrary, Health Law & Policy Institute
To protect the public from the human equivalent of "mad cow disease," U.S. Food and Drug Administration (FDA) authorities have announced an indefinite ban on blood donations from persons who spent six months or more in the United Kingdom (U.K.) since 1980. Experts estimate that the ban will reduce the pool of current donors by up to 2.2%, placing additional pressure on availability of blood products.
Transmissible spongiform encephalopathies (TSE) are chronic, progressive, and 100% fatal neurodegenerative disorders that occur in both humans and animals, which require long incubation periods for disease expression. Bovine spongiform encephalopathy (BSE), or "mad cow disease," is largely transmitted by feeding animals with meat and bonemeal derived from BSE-infected cattle and sheep. Creutzfeldt-Jakob disease (CJD) is among the TSEs that affect humans. In 1996, a "new variant" of CJD (nv-CJD) was reported in persons in the U.K., which was believed to have been transmitted by human consumption of meat from BSE-infected cattle. As a result, some scientists have suggested that no ruminant-derived products at all should be fed to animals intended for human consumption.
A recent report of the Council on Scientific Affairs of the American Medical Association (AMA) suggests that the emergence of nv-CJD in Britain was due to distinctive circumstances not found in the U.S. The report concludes that current risk of transmission of BSE in the U.S. is minimal because (1) BSE has not been shown to exist in the U.S.; (2) adequate regulations exist to prevent both entry of foreign animals into the U.S. and uncontrolled amplification of disease within the U.S. cattle population; and (3) adequate guidelines exist to prevent bovine materials from contaminating products intended for human consumption.
The FDA has banned the feeding to cattle or sheep almost any substance containing meat, bones, or fat of mammals other than pigs and horses (who are believed not to be susceptible to TSEs). However, issues of questionable enforcement of these guidelines have been raised by critics who note that the FDA has allocated the equivalent of only 17 full-time inspectors nationwide to the 14,000 facilities currently involved in feed production and rendering. Thus in large part, the absence of ruminant byproducts in animal feed relies on the honesty of feed producers. Under such circumstances, possible financial incentives to include prohibited materials in feed could be an important factor. Careful monitoring of the constituents of animal feed are critical for effectively preventing TSE-contaminated materials from reaching the human food supply.
While the FDA is appropriately erring on the side of caution in attempting to eliminate TSEs from the food chain, the effect will be a reduction in available blood supplies. A delicate balancing act will ensue between ensuring TSE-free food while maintaining the integrity of the blood supply. Accordingly, both the private and public sectors should make concerted efforts to increase the number of blood donors in order to moderate the impact of reduction in donations from the British donor ban.