A cow that was tested in November 2004, and cleared, has been retested and found to be positive after utilizing a different testing method for BSE.
This represents what could be the first native born case of BSE, with the first cow having been imported from Canada. This positive test result calls
into question to accuracy of the tests used to diagnose BSE in the United States.
The US has found its second case of mad cow disease in a cow suspected, but cleared, of having BSE in November 2004. Although meat from the cow did
not enter the food chain, the finding calls into question the accuracy of the country's BSE surveillance programme. The cow might also be the first
case born in the US.
The first US case was in a cow imported from Canada in 2003. In 2004 the country started testing "high-risk" cattle - those that show neurological
symptoms, are found dead or are "downers" (unable to stand).
Since then it has tested 375,000 cattle. None were declared positive. In contrast, Canada has tested 30,000 cattle and found three positives. The rate
at which the tests uncover positive cattle depends on the sample size, stresses Marcus Doherr of the University of Bern in Switzerland, who helped
develop Swiss BSE surveillance.
This means either that BSE is less evenly distributed in North America than thought, or that the US is missing cases. Unlike Canada, which uses the
rapid "western blot" test, the US uses a test called ELISA, which is more prone to false positives.
Please visit the link provided for the complete story.
Despite the fact that this cow never entered the food chain, the inconsistency with the testing methods currently being used is an obvious cause for
concern. Personally, I doubt that the testing being done is adequate and do not believe that the US has only had/has two cases of BSE.
According to the article, "375,000 cattle. None were declared positive. In contrast, Canada has tested 30,000 cattle and found three positives." Due
to the cross border cattle business that was going on before BSE was discovered in Canadian cattle and subsequently banned, I'm inclined to think that
the American numbers are off, particularly since the American testing method is documented to be more prone to false positives.
My question is, why do the American's continue to use such testing methods when false positives are known to more likely occur with ELISA, and will
they continue using that method even now? Granted, the cow is going to be retested once more due to the conflicting results, but why would one stick
with a testing method that is more prone for false-positives over one that has proven more reliable?
But, we also have to ask whether choosing a more reliable test is going to help matters if inadequate amounts of cattle are being tested?
To give an idea of testing practices:
The Canadian Food Inspection Agency this year (2005) testing 30,000 slaughtered cows for BSE, up from 5,490 in 2003.
In America, only less than 1 % of slaughtered cattle are going to be randomly tested for BSE. 
In Europe, "The EU will apply such a testing programme on all bovine animals over 30 months of age from 1.7.2001 onwards. Until then, all animals over
30 months which cannot be tested will need to be destroyed." 
The difference in testing makes me wonder. Why aren't more being tested? Isn't the additional cost of testing all slaughtered animals, along with feed
bans, worth it? I for one would be happy to pay for for an assurance of BSE cattle in North America.
What would be found if all animals were tested?
I don't think we should be scared to find out, because the present methods are not sufficient to keep cattle clear of BSE, and to continue testing few
animals, mainly focusing on those that show neurological symptoms, is not dealing with a potentially disastrous problem, it's just postponing what
seems to be inevitable, all the while calming the populace by testing an additional hundred thousand or so of 35 million cattle slaughtered annually.
In reality, it's doing nothing, while we continue to be provided with beef whose quality and condition cannot be assured.
National Cattleman's Beef Association