Second BSE Case Confirmed in United States

June 29, 2005 (updated) - On June 24, 2005, Agriculture Secretary Mike Johanns announced that the U.S. Department of Agriculture (USDA) received final test results from The Veterinary Laboratories Agency in Weybridge, England, confirming that a sample from an animal that was blocked from the food supply in November 2004 has tested positive for bovine spongiform encephalopathy (BSE). Five days later, DNA test results confirmed that the cow was born and raised in a herd in Texas and was approximately 12 years old. It was sent to a 3D/4D pet food plant in Texas and was selected for sampling on arrival. The animal did not enter the human food chain and was not used in the production of pet food. The animal remains were incinerated.

"The source herd is now under a hold order as we identify animals of interest within the herd," USDA Chief Veterinarian John Clifford is quoted in a statement. "Consistent with OIE guidelines, animals of interest would include any other animals that were born the same year as this animal, as well as any born the year before and the year after. If the age of the animal cannot be pinpointed, then we may expand our inquiry to include all animals in this herd before the feed ban went into place in 1997. We are also interested in any of this animal's offspring that were born within the last 2 years.

"Experience worldwide has shown us that it is highly unusual to find BSE in more than one animal in a herd or in an affected animal's offspring," Clifford continued. "Nevertheless, all animals of interest will be tested for BSE. We are also working with the Food and Drug Administration in an effort to determine the feed history in this herd. Given the animal's age, we believe it was most likely infected by consuming feed prior to the implementation of the ruminant-to-ruminant feed ban in 1997."

Currently, USDA is testing nearly 1,000 animals per day as part of its BSE enhanced surveillance program, more than 388,000 total tests since June 1, 2004, and this is the first confirmed case resulting from the surveillance.

"I am encouraged that our interlocking safeguards are working exactly as intended," stated Johanns. "This animal was blocked from entering the food supply because of the firewalls we have in place. Americans have every reason to continue to be confident in the safety of our beef."

Johanns directed USDA scientists to work with international experts to thoughtfully develop a new protocol that includes performing dual confirmatory tests in the event of another “inconclusive” BSE screening test. Effective immediately, if another BSE rapid screening test results in inconclusive findings, USDA will run both an IHC and Western blot confirmatory test. If results from either confirmatory test are positive, the sample will be considered positive for BSE.

“I want to make sure we continue to give consumers every reason to be confident in the health of our cattle herd,” Johanns said. “By adding the second confirmatory test, we boost that confidence and bring our testing in line with the evolving worldwide trend to use both IHC and Western blot together as confirmatory tests for BSE.”

The animal was selected for testing because, as a non-ambulatory animal, it was considered to be at higher risk for BSE. An initial screening test on the animal in November 2004 was inconclusive, triggering USDA to conduct the internationally accepted confirmatory IHC tests. Those test results were negative. Earlier this month, USDA’s Office of the Inspector General recommended further testing of the seven-month-old sample using another internationally recognized confirmatory test, the Western blot. Unlike the IHC, the Western blot was reactive, prompting USDA to send samples from the animal to the Weybridge laboratory for further analysis.

The laboratory in Weybridge, England, is recognized by the World Animal Health Organization, or OIE, as a world reference laboratory for BSE. Weybridge officials conducted a combination of rapid, IHC, and Western blot testing on tissue samples from the animal in question. At the same time these diagnostic tests were being run by Weybridge, USDA conducted its own additional tests.

As a non-ambulatory, or “downer” animal, the cow was prohibited from entering the human food supply, under an interim final rule in effect since January 2004. Research has shown that BSE is most likely to be found in older non-ambulatory cattle, animals showing signs of central nervous system disorders, injured or emaciated animals, and cattle that have died for unexplained reasons. USDA’s testing program targets these groups of animals for testing.

The system of human health protections includes the USDA ban on specified risk materials (SRMs) from the food supply. SRMs are most likely to contain the BSE agent if it is present in an animal. Additional measures, such as a longstanding ban on importing cattle and beef products from high-risk countries, a ruminant-to-ruminant feed ban, U.S. slaughter practices, and aggressive surveillance provide a series of interlocking safeguards to protect U.S. consumers and animal health.


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