Buyer Beware

Advertising is a way of life in the US.  We are constantly bombarded from every direction – TV, websites, billboards, radio, newspapers, apps, even public restrooms.  Those can get pretty creative.  Google it if you have time.

The important thing to remember in all of this is the “sell” part.  Whenever you buy a product, someone somewhere is making money.  Good advertising can sell rocks.  And indeed it has, making Gary Dahl $15 million in the first 6 months!

Selling a one-cent rock for $3.95 is one thing.  But what if you’re selling a test?  A test that will detect a disease in something you are planning to eat.

That’s the advertisement I saw in a recent hunting publication.  The disease it claims to detect: chronic wasting disease (CWD).

I almost fell out of my chair.  The ad is peddling a blood test kit to hunters to “assure your harvest is CWD-free!”  Ok, I DID fall out of my chair.  

I know more than a little about this disease having worked with it and deer for more than 15 years.  You may recall several blog posts I’ve written about it (The White Horse and Exploding Head Syndrome).  For those that might need a refresher, chronic wasting disease is a contagious neurological disease in cervids. Here in North America, that’s deer, elk, and moose. It is 100% fatal and was first detected in Pennsylvania in 2012.  

Testing for CWD requires postmortem collection of brain and specific lymphoid tissues.  There is only one USDA-APHIS approved test to detect the presence of CWD prions:  Immunohistochemistry (IHC) test.  And there is only one USDA-APHIS approved screening test: enzyme-linked immunosorbent assay (ELISA).

Now that I’ve picked myself up off the floor, here are a few things you should know:

• Results of these USDA-APHIS testing methods are reported as either positive, not detected, or unsuitable. Note that those results do not include “CWD-free.” That’s because a conclusive negative result is impossible because the animal may be infected but the CWD prions may not be at a high enough concentration to be detected by the test.
• Neither USDA-APHIS test is a food safety test.  
• Any approved test includes a standardized test protocol, data to support reproducibility, data to support suitability, and data to support the sensitivity (proportion of time it correctly identifies a positive sample) and specificity (proportion of time it correctly identifies a negative sample) of the test.

The test I saw advertised in that hunting publication is known as a protein misfolding cyclic amplification (PMCA) test. USDA-APHIS reports that “no company has submitted the data needed for APHIS to evaluate the PMCA prion blood test”, nor are there any “peer-reviewed scientific publications that establish the efficacy of PMCA as a detection method for CWD in cervid blood.”  

Should you have your deer tested for CWD? There is no evidence that CWD is transmissible to humans or traditional livestock. However, in light of new research, the Centers for Disease Control (CDC) recommends that hunters strongly consider having their deer tested if it is harvested in an area where CWD is known to exist. As stated, no CWD test is a food safety test nor does it guarantee an animal is not infected but it does reduce the risk of possible exposure. 

If you hunt within one of Pennsylvania’s Disease Management Areas (DMAs), free testing is available by depositing the deer head in a CWD collection container located throughout the DMAs.  And any hunter can have their harvested deer tested by the Pennsylvania Department of Agriculture (PDA) for a fee. However, that fee goes to a USDA-APHIS approved lab using a USDA-APHIS approved CWD test. 

There is nothing the wildlife community wants more than an easy, quick, affordable blood test for CWD. And some day it may be developed.  But today is not some day.  

Before you run off to purchase your CWD collection kit and pay for testing, do your research. The stakes are higher than a $3.95 pet rock.