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CWD, CJD And (Maybe) More
Unless you're involved in parkland management or neuroscience, or you're a poacher who really does their research, there's no reason for you to know, but a disease has been ravaging the deer populations of the United States and elsewhere. It's a brain-based wasting disease that bears a close resemblance, both in its effects and in its epidemiology, to "mad cow disease" (BSE), and the human equivalent, Creutzfeldt–Jakob Disease (CJD). That means it's a wasting disease characterized by progressive, degenerative neurological damage. In humans, CJD begins with progressive dementia, hallucinations and loss of cognitive function. In cows and deer, it's a little harder to track some of the more subtle neurological symptoms, but much of the physical wasting is caused by the animals forgetting to eat.
When their brains are autopsied, all three diseases show a common factor: BSE is called bovine spongiform encephalopathy because it occurs in cows and affects the brain, but also because it makes the brain take on a sponge-like appearance, with many small holes. The human and deer equivalents work the same way.
What's happening is that a complex protein, called a prion, is made wrongly, and it folds in on itself. The next thing that happens is that these misformed prions communicate their misshape to the proteins either side. Whole areas of the brain fold in on themselves and die, and the resulting spongy appearance (under a microscope) gives the whole group of diseases their name, transmissible spongiform encephalopathies. In deer, it's called chronic wasting disease (CWD) and it's spreading at an alarming rate across the deer population of the USA.
Now Scientists Think They May Have Found An Effective Vaccine
In a study published in the December 21 edition of Vaccine, the team will show that they have been able to halt the spread of cervid (deer-like animals, including elk and caribou) CWD with a vaccine. Senior study investigator and neurologist Thomas Wisniewski, MD, a professor at NYU Langone, said:
Until now, it's been impossible to halt the spread of TSEs without culling. In outbreaks of "mad cow disease", it was necessary to cull whole herds, decimating local beef industries. As many as 100 percent of captive deer in the USA are infected with CWD, making the prospect of culling a major concern. It's also worrisome because while cervid CWD can spread to other cervids like elk and caribou, BSE and its sheep equivalent, scrapie, have been shown to be transmissible to humans, causing vCJD, variant Creutzfeldt-Jakob Disease. An infected herd doesn't just hurt the meat industry, and CJD is incurable and quickly fatal, killing most of its victims in the first year and 85 percent in the first six months.
It's Small Sample, But It's Promising
The vaccine works by infecting the animals' guts with salmonella. CWD is spread by deer eating infected food or feces during natural feeeding, and Salmonella easily enters the gut. These salmonella bacteria were "attenuated" — no longer dangerous. They had a prion-like protein inserted into their genome. It's thought that the vaccine works by triggering the production of anti-prion antibodies.