There was good news last month on both sides of our northern border: In response to confirmation of an isolated case of bovine spongiform encephalopathy (BSE), or "mad cow disease," in a Canadian cow, <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />U.S. regulators declined to ban Canadian beef imports. This decision, which reflects sound science and wise trade policy, will prevent unnecessary disruptions of the supply and price of beef on both sides of the border.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Alas, it was not always so. The United States—followed by 33 other countries—prohibited Canadian cattle imports in 2003 after the first case of BSE was discovered in Alberta. (Last week's is the fifth overall.) The embargo skewered the cattle industry in Canada and led to higher prices in the United States, which imports significant amounts of beef from its neighbor. That U.S. ban was finally lifted in January of last year.
Although U.S. Secretary of Agriculture Mike Johanns said that the discovery of the BSE-infected cow would not affect Canadian imports to the U.S., South Korea on Tuesday canceled scheduled talks with Canada on resuming imports of Canadian beef. South Korea's ban on Canadian beef dates from the 2003 discovery of Canada's first case of BSE.
BSE is a progressive neurological disorder of cattle caused by infection with an odd infectious agent called a prion. It appears that the infectious prion, a modified form of a normal cell surface component known as prion protein, arises from a mutation. The pathogenic protein differs by being both less soluble and more resistant to enzyme degradation than the normal form.
The first infections of BSE in cows in the 1970's are thought to have originated from the feeding of infectious prion-contaminated sheep meat-and-bone meal to cattle. The outbreak was amplified and spread throughout the British cattle industry by the practice of feeding rendered bovine meat-and-bone meal to young calves. At the peak of the BSE epidemic in the United Kingdom in January 1993, there were almost 1,000 new cases per week, and through April 2005, more than 184,000 cases of BSE, in more than 35,000 herds, had been confirmed in the United Kingdom.
There is strong epidemiologic and laboratory evidence that BSE in cattle can cause a fatal neurodegenerative disease of humans called variant Creutzfeldt-Jakob Disease, or vCJD. The BSE outbreak in the UK is believed to have caused 143 cases of this disease. In order to prevent potentially BSE-infected tissues from entering the human food supply, a variety of public health control measures such as surveillance, culling sick animals, and banning from human food certain high-risk materials (such as mechanically recovered meat from the vertebral column of animals) have been introduced in many countries, particularly those with indigenous cases of confirmed BSE. It is now exceedingly unlikely that BSE-infected animals will find their way into the food supply in the United States, Canada or Europe—from either domestic or imported animals.
Not surprisingly, some U.S. beef producers would like to see the prohibition on Canadian beef restored and maintained until the cows come home. They cite safety concerns, but the real reason is pure economics: Like their counterparts in the steel, automobile and sugar industries, domestic beef producers endorse protectionism—when it benefits them—and salivate at the prospect of the higher prices for cattle that would result from restrictions on imports.
In the best interests of all stakeholders (and steakholders), scientific considerations—not protectionism or hysteria about food safety—must dictate decisions about beef imports and exports. This is critical because even with the most strict and prudent animal husbandry and testing practices, all cattle-producing nations will still see occasional cases of BSE.
How can that be?
We know that there are "sporadic" cases of vCJD, the human equivalent of BSE, which appear to be caused by a spontaneous mutation that gives rise to misfolding of a prion. Evidence from several sources suggests that there is an analogous situation in cows, with BSE-like illnesses arising not from other animals via "infection," but spontaneously.
This is important, for two reasons. First, because no amount of testing will eradicate the spontaneous—and extremely rare—appearance of BSE and similar illnesses; and second, because current practices (especially prohibitions on feeding offal derived from neurological tissues to animals) will prevent lateral transmission to other animals from a cow suffering from spontaneous BSE. Thus, there is no need to destroy whole herds or to embargo exports, with the resulting damage to ranchers' livelihood and international trade.
Science-based public policy and free trade can steer a course that will ensure our ability to bring home the bacon (or beef) at a reasonable price.