The second case of mad cow disease (bovine spongiform encephalopathy, or BSE) in the United States has led to heightened scrutiny by critics and fine-tuning of the testing process, but has had little impact on domestic economics or consumer confidence. “The U.S. has gotten off more lightly than other countries such as Germany, which had only seven cases in 2001 but had a huge public outcry,” says Kate O'Neill, associate professor in the UC Berkeley Department of Environmental Science, Policy and Management.

BSE was first found in the United States in December 2003 in a Washington state cow that originally came from Canada. This case led to the collapse of the U.S. beef export market, which used to account for one-tenth of U.S. beef production. While some countries have since lifted their bans on U.S. beef, others have not and the export market is far from recovered.

In contrast, there has been little economic reaction to the second U.S. BSE case, which was confirmed in June 2005 in a Texas cow. “The impact of the second case has been pretty negligible,” says Donald Klingborg of the UC Davis School of Veterinary Medicine. For example, while Taiwan and the Philippines banned U.S. beef immediately after the second case was confirmed, these bans were short-lived. “However, the second case might still have a long-term economic impact if it keeps other countries from lifting bans that have been in place since the first case,” Klingborg adds. The most significant of these countries is Japan, which had been the most lucrative beef export market and accounted for $60 million in California and $1.5 billion nationwide. In 2004, Japan said it would reopen its market to U.S. beef in 2005. While this has yet to occur, Japan has said that the second U.S. BSE case will not affect the planned resumption of trade.

Debate over testing policy

Perhaps the biggest impact of the second case has been on the debate over U.S. policy on BSE testing ( see page 203 ). “It has given strength to consumer group arguments that we're going about testing all wrong,” O'Neill says. In 2004, the United States vastly expanded its testing program to assess the incidence of BSE nationwide. Called a surveillance plan, the expanded program was designed by an international group of experts to be able to detect one case of BSE in a million cows. This entails testing all identified cows from the highest-risk populations: downers, which can no longer walk, and cows older than 30 months with BSE symptoms such as emaciation and unusual behaviors, from agitation to kicking. Focusing on high-risk populations “is like using a canary in a coal mine,” Klingborg says.

To date, the United States has tested more than 470,000 cattle for BSE. Critics such as the Organic Consumers Association say this is far too few, given that there are about 96 million cattle nationwide, of which about 36 million are slaughtered each year. In comparison, Japan tests every cow slaughtered and the United Kingdom tests a quarter of them. However, Japanese testing is driven by consumer demand and the United Kingdom has had more than 180,000 BSE cases altogether, neither of which applies to the United States. “BSE is at such a low level here that it doesn't make sense economically to test all cows,” says Alex Ardans, director of the California Animal Health and Food Safety Laboratory System (CAHFS) at UC Davis, one of seven nationwide that screen cows for BSE.

Critics also call for testing cows before the 30-month cutoff because Japan has found BSE in two cows that were younger (21 and 23 months). However, the overwhelming majority of positive BSE cases are in cows older than 30 months, and there is a key distinction between the Japanese and U.S. testing programs. “The U.S. program is not food safety testing,” Ardans says. Rather than determining whether cows slaughtered for human consumption are BSE-free, the goal is to assess whether the disease is present in the U.S. cow population and, if so, where and how widespread it is.

Changes in testing program

The second U.S. BSE case prompted important changes in the U.S. cattle-testing program for BSE. All along, the first step in this program has been a rapid screening test called an enzyme-linked immunosorbent assay (ELISA). This antibody-based test costs about $25 per sample, and the CAHFS lab at UC Davis can process up to 550 per day. If the ELISA result suggests that a sample may be BSE-positive, the next step is confirmatory testing at the National Veterinary Services Laboratory in Ames, Iowa. Between June 2004 and Sept. 18, 2005, only two of the more than 470,000 samples screened had gone on for confirmatory testing.

Originally, that meant doing an immunohisto-chemistry (IHC) test, which takes 4 to 7 days and has two components: examining brain tissue for the spongy-looking areas characteristic of BSE, and testing the tissue with antibodies. However, the IHC test failed to catch the second U.S. BSE case, which was ultimately confirmed by another, more sensitive antibody-based test called a Western blot. As a result, future confirmatory testing will include both the IHC and Western blot tests. The latter costs about $500 and takes about 2 days.

The second U.S. BSE case may also hasten parts of the testing program that are planned but have not yet been implemented. For example, in addition to testing downers and cows with BSE symptoms, the program is supposed to test 20,000 healthy-looking cows brought to slaughterhouses.

Livestock tracking several years away

The second U.S. BSE case also underscored the importance of being able to track individual cows. Federal investigators were unable to trace all the herd mates and offspring over the lifetime of this 12-year-old Texas cow, so the question of whether any of them also had BSE remains unresolved.

Livestock tracking is already required in countries such as Canada, the United Kingdom and Japan. Effective January 2009, the U.S. National Animal Identification System will also require U.S. producers to track all cows and other meat-producing livestock. For cows, tracking will likely be via radio-identification ear tags that send information automatically to a national database.

O'Neill says that while the risk of BSE may be small in the United States, the significance of the second case should not be downplayed. “BSE is indicative of larger problems in industrialized agriculture,” says O'Neill, noting that avian flu and other diseases that spread among species could pose a larger health threat to people. “Economic integration brings other kinds of integration,” she says. “Food and animals are shipped around the world, and countries need to work together better.”