In case you were too busy to see the news Friday evening, Agriculture Secretary Mike Johanns mentioned a second cow may have tested positive for bovine spongiform encephalopathy, or BSE (aka ‘Mad Cow’ disease). More tests will be conducted in order to conclusively state if the cow had disease. These additional tests are a requirement because of the following:
- - 375,000 animals from the targeted cattle population have been tested for BSE using a rapid test. From these 375,000, 3 tests came back as inconclusive.
- - Samples from those three cattle were then tested under what is known as immunohistochemistry (IHC) testing. The three samples came back as negative.
- - Samples from the same three cattle were then tested under a procedure known as the Western Blot test, a internationally recognized confirmatory test. From this test, the results were two negatives and a positive.
- - Since the one postive had also been tested as inconclusive (using one test) and negative (using a second), further tests will be conducted from samples from the one cow.
Okay, first things first: Apparently this is not a new case being tested. This positive comes from the same cows previously reported on earlier this year.
However, that being said, I still have some thoughts. Although 375,000 cattle tested sounds like an impressive number, consider that there is possibly over 100 million heads of cattle in the United States. (I got that number by doing some basic math on Nebraskas claim of having 6.6 million heads of cattle and having 6.75% of the US cattle population). That means that only .375 of 1% is being tested for BSE. I’ll leave it up to you to decide if that’s adequate or not. In my own opinion (based off a statistical analysis class from college many years ago, and not much more), they need to bump the percentage up a bit. But again, I’ll leave that up to you, the reader.
Secondly – If a positive is pulled from one test, but not another, then one of the two is wrong. Whichever test is determined to be incorrect needs to be evaluated thoroughly. Yes, economic factors need to be evaluated as well, but even if this test is correct 99% of the time, on 375,000 heads of cattle, that means that 3750 tested cows gave incorrect answers. That’s simply unacceptable given the seriousness of the scope of the issue here.
As noted here before, the USDA is not testing friendly when it comes to BSE. There’s a reason for this: Money. If you read the news today, stocks are falling, especially in the food sector, based off of this news. Tawain has already stated that it will ban Beef imported from the U.S. if the final tests come back as positive. There’s money to lose here, and lot’s of it. Keep the following in mind – The USDA is tasked with helping to “ensure open markets for U.S. agricultural products”, not necessarily maintaining public health. I believe, in the case of BSE, the interest of the general public is not being met, even if the needs of cattle producers are.
As always, when it comes to beef, know where it is coming from. The better you are at determining the ranches and farms that your beef is coming from, the better the odds are that you are eating from a place that keeps public health in it’s mind.
(Thanks to US Food Policy for the heads up)
UPDATE: Teal Sunglasses let’s me know that my statement of “Secondly – If a positive is pulled from one test, but not another, then one of the two is wrong.” is, in of itself, incorrect.
Many times, the initial test used to screen issues like this is used not because it’s accurate, but because it’s fast and cheap. the idea is to quickly screen out what is NOT potentially infected, and then go back to those that tested positive and use a slower (more expensive) but more accurate test to see if you’re really infected.
I should note that the tests actually came back inconclusive first, then negative and then positive, rather than the other way around. It was only through the work of John Stauber at the Center for Media and Democracy, and other folks who asked (some would say demanded) that the the Gov’t use the Western Blot test. It was only with the Western Block test that the postive came back. I think this indicates that the immunohistochemistry testing is questionable as far as it’s adequacy is concerned.
If the IHC pulled a postive, and then the Western Blot test pulled a negative, I would be in full agreement.