The Science
The basics
What is CWD and how do deer get it?
CWD is a progressive and fatal neurological disease that affects deer, elk, moose, and other cervids. Though there are still open questions, the cause of CWD has been traced back to abnormal proteins called prions. Prions are misfolded proteins that can induce other normal proteins to misfold and accumulate in the brain, leading to damage and cell death.
CWD is considered a transmissible spongiform encephalopathy (TSE), similar to diseases in other animals, such as bovine spongiform encephalopathy (BSE or "mad cow disease") in cattle and scrapie in sheep. The prions associated with CWD are highly resistant to normal decontamination procedures, making the disease particularly challenging to manage.
Deer contract the disease by coming into close and direct contact with infected prions in the environment. This could include contact with other infected deer, animal remains, interactions with infected animals, as well as through environmental contamination - primarily ingested through their feed.
These aberrant protein variants induce the misfolding of nearby normal proteins, causing harm to nerve cells. Animals affected by CWD experience symptoms like lethargy, disorientation, and the inability to eat or drink, leading to eventual death.
The Cure
What is Humic Acid?
"Acid" sounds like a scary word. Even though Humic Acid is technically an acid, it's not a burning acid that's releasing a white smoke from a test tube. Humic Acid is just an organic compound found in rich humus soil in the environment.
It has been discovered that Humic Acid breaks down the misfolded brain proteins (prions) that cause chronic wasting disease. Since the primary way deer come into contact with these infected prions in the environment is through their feed, treating that infectious source can measurably reduce the risk that a deer contracts the disease.
The Research
How do we know?
It started with a scientific study done at the University of Alberta by Judd Aiken, who is a prion disease researcher. What they conclusively discovered is that when concentrations of humic acid were applied to CWD-infected brain tissue, chemical signatures of the infectious prions were nearly eliminated. The application of the humic acid to the infection degraded the warped proteins, in some cases significantly reducing, and in others completely eliminating the infectivity of the material.
It's already been shown through lab experiments that prions have the ability to persist in soil for long periods of time. In a recent exploration, wildlife biologist Bryan Richards from the U.S. Geological Survey's National Wildlife Health Center here in Wisconsin pointed out the significance of soil mineralogy in the dissemination of prions. He notes that prions exhibit a strong affinity for minute minerals like quartz, kaolinite, and montmorillonite - and can stay locked in the soil for years.
This new discovery of how humic acid affects prions finally gives us a path to prevent and control the spread of this disease. Since quantities of humic acid naturally occuring in the environment vary significantly by area, scientists exposed infected elk brain tissue to 1, 2.5 and 25 grams per liter of humic acid, and then let it incubate overnight. In the samples that were exposed to the higher concentrations of humic acid, the infectious prions decreased by as much as 95%.
Next, researchers tested using mice. They injected one group of mice with a mixture of humic acid and infected elk brain tissue. The second group of mice were given a noninfected mixture. The mice were then monitored for about a year. The mice with higher doses of humic acid showed test results of weaker prion signals in the infected mice. In about 50% cases, the group of infected mice who were treated with humic acid didn’t show any symptoms at all after a 9 month monitoring period.