The U.S. Department of Agriculture has approved two mad cow tests made by Swiss company Prionics, the firm's officials said Thursday.
The approval also clears the way for U.S. researchers to use the so-called Western blot method of testing, which is often thought to provide more sensitive results than some other tests.
The USDA also approved Prionics' Check LIA test, which is similar to a protocol known as Elisa testing. Prionics' tests will be distributed in the United States by Roche Diagnostics.
Both the Elisa and Western blot techniques work by looking for malformed prions, or specialized proteins, that are the signature of mad cow and related diseases.
Researchers take a sample of an animal's brain and destroy all the normal prions, leaving behind any abnormal ones, which give away the presence of the disease. The Western blot provides a more detailed "signature" of these abnormal proteins, though it often takes longer to process.
In recent weeks, USDA approved other Elisa-type tests, including those from California firm Bio-Rad and Maine company Idexx. Abbott Labs, based in Illinois, announced Wednesday it had won approval for its Enfer tests, another Elisa-type test that can return results in about 3 1/2 hours, slightly faster than the others.
The Enfer tests were developed by Enfer Scientific of Ireland, where officials tested nearly 40 percent of the 1.8 million cattle slaughtered last year.
U.S. officials have been scrambling to respond to the nation's first case of mad cow disease, found last December in a Mabton, Wash., dairy cow. Among their efforts is a significant increase in testing for the disease, with 200,000 or more cows to be checked in the next 18 months, up from 20,000 last year.
The one-time testing increase is significant, but would still leave the U.S. far behind many European countries and Japan, which tests every cow intended for human consumption.
Food safety advocates and even some beef producers have called for broader testing, some even demanding universal tests similar to Japan's. Major meat packers and government officials have dismissed such moves as scientifically unjustified, and insist the tests are intended to check for the disease's presence, not for food safety.
Instead, USDA officials say new restrictions on the use of some cattle parts, which the agency said Wednesday would cost the beef industry some $150 million this year, should guarantee the meat supply is safe.
Many types of testsU.S. testing for bovine spongiform encephalopathy, as the fatal brain disease is formally known, will occur at seven state veterinary labs across the country. The labs will be allowed to choose the tests they wish to use, though any initial positives will be sent to the USDA's lab in Ames, Iowa, for confirmation using a comprehensive process known as immunohistochemistry.
Fabio Rupp, Prionics' representative in North America, said the company recommends Western blot tests, despite their slightly lower price tag, because of a lower potential for false positive results. He said the current test can be run in a few hours, about what is required for other tests.
"There is ample evidence that it is a very reliable test," Rupp said.
Western blot tests were also used by Italian researchers to help identify an apparent new type of mad cow disease, which they reported in February. The tests helped show that the type of BSE found in several Italian cows differed significantly from that found in other infected cattle.