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‘Zombie deer disease’ epidemic spreads in Yellowstone as scientists raise fears it may jump to humans
A new article that announces more CWD incidence and summarizes the problem.
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The disease is a “slow-moving disaster”, according to Dr Michael Osterholm, an epidemiologist who studied the outbreak of bovine spongiform encephalopathy, or “mad cow disease” – a related prion condition – in the UK, and is director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
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Like with other diseases, it reveals the consequences of various human activities, long-running exponentially evolving consequences.
You don't want to mess with prions. Unfortunately, the prions are also present in urine and other excretions from the sick animals, so it can get on grass or other surfaces.
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So when do we expect hunters to start dying from prion diseases? I don't think we'll know. It's going to be a surprise. With all the things tied to dementia now, it may just be one part of a complex causal pathway, a comorbidity.
Here's a nice microbiology podcast that goes a bit into prions: https://www.microbe.tv/twiv/twiv-878/
Here's a paper that shows that CWD can get into humans: https://link.springer.com/article/10.1007/s00401-022-02482-9 (unfortunately, tested on mice)
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Notably, our data suggest a different clinical presentation, prion signature, and tissue tropism, which causes challenges for detection by current diagnostic assays. Furthermore, the presence of infectious prions in feces is concerning because if this occurs in humans, it is a source for human-to-human transmission. These findings have strong implications for public health and CWD management.
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Here's another study: https://wwwnc.cdc.gov/eid/article/24/8/16-1888_article
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elk CWD prions could convert human PrPC from human brain and could also convert recombinant human PrPC expressed in transgenic mice and eukaryotic cell cultures
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As mentioned above, the prions can remain on the ground, on various surfaces. This makes things more interesting:
Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions https://www.cell.com/cell-reports/fulltext/S2211-1247(15)00437-4
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Surprisingly, the small quantity of PrPSc naturally excreted in urine and feces from sick hamster or cervids was enough to efficiently contaminate plant tissue. Indeed, our results suggest that the majority of excreted PrPSc is efficiently captured by plants' leaves and roots. Moreover, leaves can be contaminated by spraying them with a prion-containing extract, and PrPSc remains detectable in living plants for as long as the study was performed (several weeks). Remarkably, prion contaminated plants transmit prion disease to animals upon ingestion, producing a 100% attack rate and incubation periods not substantially longer than direct oral administration of sick brain homogenates. Finally, an unexpected but exciting result was that plants were able to uptake prions from contaminated soil and transport them to aerial parts of the plant tissue. Although it may seem farfetched that plants can uptake proteins from the soil and transport it to the parts above the ground, there are already published reports of this phenomenon. The high resistance of prions to degradation and their ability to efficiently cross biological barriers may play a role in this process. The mechanism by which plants bind, retain, uptake, and transport prions is unknown.
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Plants, as they often do, take up a lot of stuff from the soil. Sometimes it's heavy metals. In this case, it can also be prions. What this means is that cervids may contaminate various places where they hang out, such as grasslands. Where domestic herbivores are brought to graze. Do I need to say it?
From the same paper:
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Epidemiological studies have shown numerous instances of scrapie or CWD recurrence upon reintroduction of animals on pastures previously exposed to prion-infected animals. Indeed, reappearance of scrapie has been documented following fallow periods of up to 16 years, and pastures were shown to retain infectious CWD prions for at least 2 years after exposure.
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Interesting times ahead. This doesn't mean that we should just sit idly by and watch the meat industry, including it's extensive form, collapse under the burden of its own unleashed horrors.