A positive case of BSE on American soil has raised questions about how the United States tests for the disease.
U.S. Department of Agriculture officials have launched an investigation into the origins of the infected cow, rumoured to be from Texas.
Brain samples taken from the animal were tested and pronounced negative last November. After the USDA’s office of the inspector general criticized the surveillance program, chief inspector Phyllis Fong ordered a further test at the world reference laboratory in Weybridge, England where the sample was declared positive.
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The western blot test and the immunohistochemistry test were used to confirm the diagnosis, said U.S. secretary of agriculture Mike Johanns in a news conference June 24.
The inspector general’s audits of the surveillance program are ongoing with a report expected this summer. Johanns promised the procedures would be upgraded.
“I have directed our scientists to work with international experts to develop protocol for simultaneously performing the IHC and the western blot test in the event of another inconclusive screening test,” he said.
The test showed signs of BSE prions found in BSE cases discovered in France, said USDA veterinarian John Clifford. The U.S. test may have been calibrated to detect only the English type.
The animal was not likely imported but Canada is not fully in the clear because the investigation will include the feed source.
That information hinges on the accuracy and detail of the ranch’s information, said John Masswohl, trade analyst with the Canadian Cattlemen’s Association.
“In the U.S. where they don’t have a lot of these mandatory record keeping requirements, it may be difficult for them to do the full trace out of the animal’s whole life as well as the feed,” he said. “The farther away it is from here, the less likely the feed came from Canada.”
Masswohl does not expect a consumer backlash and expects less emotion over this discovery compared to Canada’s first case announced in May 2003.
The U.S. lost more than 30 export markets when a case was found in an imported cow December 2003. The U.S. is not as reliant on exports as Canada, so its cattle prices suffered little.
However, Taiwan halted trade because its agreement was on the basis of the U.S. being BSE free, said Ted Haney of the Canada Beef Export Federation. Trade resumed in April but stopped following the June 24 announcement.
Joe Schuele, a National Cattlemen’s Beef Association spokesperson, said the test results were not a surprise. As the largest beef lobby group in the U.S., it favours a consistent testing regimen for all labs across the country.
“The positive test is well within what our expectations were when we started the enhanced surveillance program and we don’t find it alarming that there has been a positive test found,” he said.
Schuele also said rapid screening tests flag suspect animals and pull them from the food and feed system for further examination.
“That is the test that really takes that animal out of circulation,” he said.
However, one consumer group wants improved testing and a wider feed ban.
Mike Hansen, a research analyst with the Consumers Union in New York, said testing has not been adequate and the USDA has not given enough information.
“We’re glad they’re going to use the western blot as a confirmatory test, but they have to start releasing some statistics and being more transparent on these 388,000 animals that they have tested as part of the surveillance program,” Hansen said.
His group wants to see all slaughter animals older than 20 months tested and to use the western blot test on a regular basis to confirm inconclusive results.
The blot test method processes brain material to detect a certain protein by using an antibody specific to that protein. If three blots appear after processing, the sample is positive for BSE. The consumers group also wants a strengthened feed ban where poultry manure and restaurant plate waste are not used in animal feed.
In a prepared statement, R-CALF agreed with a stronger feed ban and said testing levels should increase.
However, the cattle producers group continued to insist Canada is a higher risk country because it discovered its first BSE case in 1993, in a cow imported from England.
Further, it said Canada is not testing enough and given that four positive cases have appeared, the population is likely at a higher risk than the U.S.
“Just the fact that Canada has had four cases of BSE in native cattle in the past two years suggests the prevalence rate of the disease is higher in Canada than in the United States,” said president Leo McDonnell in a statement.
