Conflicting results: Old ‘inconclusive’ may be BSE positive

SALEM, Ohio – Seven months after the USDA confirmed an inconclusive BSE test was not mad cow disease, a second test said otherwise.
Last week, the USDA’s Office of Inspection General recommended the three cows that tested inconclusive for bovine spongiform encephalopathy (BSE) in 2004, be re-tested using what is known as the Western blot test.
One of those animals, a cow initially inconclusive in November, screened positive with this new test. The other two were negative, Agriculture Secretary Mike Johanns announced at an evening press conference June 10.
The USDA is now having a reference lab in Weybridge, England, look at the brain sample.
The department is also conducting further testing, which will take several days, said APHIS Chief Veterinary Officer John Clifford.
‘No risk.’ “The animal was a downer animal,” Johanns said. “It did not get in the food or the feed chain. There just is no risk whatsoever.”
Clifford described the cow as “aged” and a “beef breed” and said there was no information indicating it was an imported animal.
“It was processed at a facility that handles only animals unsuitable for human consumption, and the carcass was incinerated,” he said.
Testing. More than 375,000 animals have been tested since the program was put in place after the U.S.’s first BSE case in December 2003.
Of those 375,000 animals, three tested inconclusive using a rapid test. Further immunohistochemistry (IHC) testing was done and the samples came back negative for BSE.
The Office of Inspection General operates independently and requested the Western blot test be done on these samples, Johanns said.
This test is also an internationally recognized test, but both the Western blot and IHC are rarely used together in other countries unless there are unusual circumstances, Clifford said.
‘Weak positive.’ When the U.S.’s first positive BSE case was found in December 2003, Clifford said the Western blot test recorded a “very strong positive.”
In this case, however, 20 times the amount of abnormal protein was used to come up with a positive, meaning this was a “weak positive test,” he said.
Trade. Johanns emphasized he did not think this news would impact trade discussions with Japan, Korea or Canada.
Discussions with Japan have been related to animals under 20 months, Korea under 30 months and Canada under 30 months, he said, again reiterating that the cow in question was an “aged animal.”
“They’ll want to know what the issues are and what we have done, and we’ll provide them with that information,” Johanns said, adding that he had the results for just 10 minutes before he began the conference.
Questions. R-CALF United Stockgrowers of America said the public shouldn’t overreact to this announcement.
But President Leo McDonnell also raised some concerns.
“Why would USDA not have re-tested this animal over seven months ago if it had any doubts as to the accuracy of its tests?
“USDA’s past actions have unnecessarily traumatized U.S. cattle producers, and this situation raises the need for further questioning of USDA’s handling of the entire BSE issue,” he said.
(Reporter Kristy Hebert welcomes feedback by phone at 800-837-3419, ext. 23 or by e-mail at khebert@farmanddairy.com.)