The CWD scam

[elkhunter505]

How exactly is the science on cwd very clear? My understanding is we are still are still trying to prove/disproves the theories on how tse’s work. Sounds like you are pretty up to date - do you have any good references to share?

Sorry, let me be more specific. The science surrounding how it impacts deer herds, how it spreads, and how to kill it is clear. We are still uncertain about the risk to humans because there hasn't been any evidence of spread yet.

When we think about how CWD moves across the landscape, they use the ecological diffusion model a lot of the time. That model basically quantifies how CWD spreads across different habitat types. In that sense, in heavily forested areas, it is harder for deer to move and congregate than it is in agricultural fields or other habitat types. So based on GPS telemetry data about the natural movement process, they can use habitat type data to estimate how fast CWD will spread and where it is most likely to spread in the future based on where we know that CWD is currently and how prevalent it is in those areas. The ecological diffusion models that have been published have been shown to fit the true CWD spread process very well; however, because of the scale of CWD, it is very computationally intensive to fit that model to a large dataset so they rely on simulation modeling to take models like that and make predictions into the future. In this sense, they rely on papers from the past that show true data in how CWD spreads across the landscape and then build simulation models off of those dynamics. They then add some uncertainty surrounding each parameter in those models and run the simulations 100s or 1000s of times to get a bunch of different scenarios of how CWD spreads under different scenarios. The hard part for the public and for the modelers is the models get so complicated when we are trying to make them as close to the true process as possible that they become a black box to many people including me sometimes. The models use differential equations and all sorts of other calculus, algebra, and statistics which in this sense is likely not understandable to the normal person that isn't trained in these methods.

For example, this paper, is unbelievably dense but showed that their model accurately predicted and forecasted the true process using data from over 100,000 whitetails that were harvested and tested (2562 positives) in Wisconsin between 2002 and 2014. Figure 6 is a bit weird to look at but it gives you a sense of the accuracy of their predictions and forecasts in comparison to the data that they have available. In this case, they built a mechanistic model, which basically means constraining certain portions of the model based on the ecological knowledge that we have, to fit their data. They proved that their model forecasted, aka predicted prevalence rates into the future, better than other models that did not contain mechanisms and just fit based on data alone. They created forecasts by simulating that model into the future based on how it fit previous data and found it close to the true process.

However, for the average person to look at this type of model and see that they are constraining the process through a mechanism can sometimes feel like they are making the model "do what they want" when what they are truly doing is using the knowledge we've gained in the past from previous studies to help the model find realistic solutions. An example of how data could give unrealistic solutions would be just random chance of the data that you get from collared animals on their survival. Many mammals experience the lowest survival rates when they're young and then that survival rate becomes better and better as they age. If you don't have a high enough sample size, the distribution of the ages of the animals you have collared may not be truly accurate of the population. In this sense, if you have few young animals and more old animals and more of the old animals die, a model with no mechanism is going to estimate a higher survival probability for the younger animals than the older animals even though we know that is likely not true. If you put a mechanism in place, it can allow your model to give you more realistic estimates with the data that you have because in general, we know that neonates are at the highest risk of death and older animals are at the lowest.

Edit for typo on the old vs young animal survival.

 

[Reburn]

Most of the incinerators used by Wyoming are 1,800+ degrees, the state vet lab and at Sybille.

1800C or 1800F?

I was speaking in Celcius. Hence the C. 1000 Celsius is 1832 fahrenheit.

While I dont know for fact. I doubt they are operating an incinerator at Ti smelting temp of 1800c or 3200f.

 

[taskswap]

Anyone can look up that the likelihood of contracting CWD from eating deer meat is next to zero, or actually, at this point is zero. Every peer reviewed study that I can find demonstrates that. Yet, because there is an extremely faint theoretical possibility that it could adapt to cross the brain barrier, they still recommend not eating it.

And there hasn’t ever been a known verified case of CWD being transmitted to humans from eating or handling deer meat.

Be careful with this one. Even the scientists studying CWD acknowledge there hasn't been a documented case of transmission. That's not the point. Many things that never infected us before have evolved to do so. Prions evolve more quickly than many other organisms, so the worry isn't that they DO, it's how easily they MIGHT. Prions crossing the species barrier has already been observed in lab settings, and we've watched the same thing happen in the wild with fungal and bacterial infections as well. And bear in mind, we currently have NO treatments for these diseases.

The goal here is to close the gate before the horse is out, not wait and say "whoops, we knew this was a possibility, but did nothing, sorry folks..."

If you saw a hole in a wall that said "cows that stick their tongues in here often die of a terrible disease, but it hasn't been shown to kill a human yet..." would you stick your tongue in there?

 

[elkhunter505]

The goal here is to close the gate before the horse is out, not wait and say "whoops, we knew this was a possibility, but did nothing, sorry folks..."

This is a great analogy. It would be like if we had the knowledge of invasive species that we have now before feral hogs were a problem in the US and we allowed people to continue importing them because hogs specifically hadn’t escaped a high fence yet and we thought our normal containment methods sufficed.

 

[RockAndSage]

1800C or 1800F?

I was speaking in Celcius. Hence th C. 1000 Celsius is 1832 fahrenheit.

While I dont know for fact. I doubt they are operating an incinerator at Ti smelting temp of 1800c or 3200f.

A little more perspective on how serious of a problem prions are: the melting point of lead is 621F. This biological material can survive molten lead, with specified sterility temperatures being 3x hotter.

 

[Skerhunter]

T

Sorry, let me be more specific. The science surrounding how it impacts deer herds, how it spreads, and how to kill it is clear. We are still uncertain about the risk to humans because there hasn't been any evidence of spread yet.

When we think about how CWD moves across the landscape, they use the ecological diffusion model a lot of the time. That model basically quantifies how CWD spreads across different habitat types. In that sense, in heavily forested areas, it is harder for deer to move and congregate than it is in agricultural fields or other habitat types. So based on GPS telemetry data about the natural movement process, they can use habitat type data to estimate how fast CWD will spread and where it is most likely to spread in the future based on where we know that CWD is currently and how prevalent it is in those areas. The ecological diffusion models that have been published have been shown to fit the true CWD spread process very well; however, because of the scale of CWD, it is very computationally intensive to fit that model to a large dataset so they rely on simulation modeling to take models like that and make predictions into the future. In this sense, they rely on papers from the past that show true data in how CWD spreads across the landscape and then build simulation models off of those dynamics. They then add some uncertainty surrounding each parameter in those models and run the simulations 100s or 1000s of times to get a bunch of different scenarios of how CWD spreads under different scenarios. The hard part for the public and for the modelers is the models get so complicated when we are trying to make them as close to the true process as possible that they become a black box to many people including me sometimes. The models use differential equations and all sorts of other calculus, algebra, and statistics which in this sense is likely not understandable to the normal person that isn't trained in these methods.

For example, this paper, is unbelievably dense but showed that their model accurately predicted and forecasted the true process using data from over 100,000 whitetails that were harvested and tested (2562 positives) in Wisconsin between 2002 and 2014. Figure 6 is a bit weird to look at but it gives you a sense of the accuracy of their predictions and forecasts in comparison to the data that they have available. In this case, they built a mechanistic model, which basically means constraining certain portions of the model based on the ecological knowledge that we have, to fit their data. They proved that their model forecasted, aka predicted prevalence rates into the future, better than other models that did not contain mechanisms and just fit based on data alone. They created forecasts by simulating that model into the future based on how it fit previous data and found it close to the true process.

However, for the average person to look at this type of model and see that they are constraining the process through a mechanism can sometimes feel like they are making the model "do what they want" when what they are truly doing is using the knowledge we've gained in the past from previous studies to help the model find realistic solutions. An example of how data could give unrealistic solutions would be just random chance of the data that you get from collared animals on their survival. Many mammals experience the lowest survival rates when they're young and then that survival rate becomes better and better as they age. If you don't have a high enough sample size, the distribution of the ages of the animals you have collared may not be truly accurate of the population. In this sense, if you have few young animals and more old animals and more of the old animals die, a model with no mechanism is going to estimate a higher survival probability for the younger animals than the older animals even though we know that is likely not true. If you put a mechanism in place, it can allow your model to give you more realistic estimates with the data that you have because in general, we know that neonates are at the highest risk of death and older animals are at the lowest.

Edit for typo on the old vs young animal survival.

Thanks for sharing! I haven’t researched any of the ecological studies like this.

Do you know what the assumptions are for the mode of transmission used in this model, if any? Since we can’t confirm the actual mode of transmission currently, I could see how a model like this could help narrow it down. Until we understand the actual mode(s) of transmission, I don’t see how we could come up with a viable solution (example - it’s maternal and we reduce population 99% but now we have 100% positive population or it’s environmental and remove all deer, but in 10 years the new population has the same number of positive animals).

My understanding is we currently can’t prove cwd can infect humans, using the same models that have been proven to show BSE can. That is good news!

 

[Skerhunter]

A little more perspective on how serious of a problem prions are: the melting point of lead is 621F. This biological material can survive molten lead, with specified sterility temperatures being 3x hotter.

Can’t prions be denatured via basic steam sterilization? I have seen multiple sources cite utilizing elevated temperatures and time is acceptable (much below what an incinerator is run at).

 

[KBaird]

Prions aren't something I want to mess with. If an animal tests positive for CWD, I'm not going to eat it, nor would I make the rest of my family eat it.

Not intending to single you out specifically, but your comment was short and to the point…


How do the throw-out-the-meat guys rationalize handling a positive carcass before you have a test? If you’re willing to toss the edible portions, that carry very little if any prions, how do you go about caping, deboning, boiling skulls, etc, which can/likely do expose one to far more prions?

I’ve read at least one study the prions can be ingested via aerosol. Are you guys not scared of breathing them in when caping or boiling?

Are you sure the skull you hang in your house is completely prion free?

Are you guys packing a hazmat suit into the backcountry?

Tough for me to rationalize throwing out the meat but being perfectly fine with handling all the parts and pieces that actually contain prions in the meantime.

 

[elkhunter505]

T

Thanks for sharing! I haven’t researched any of the ecological studies like this.

Do you know what the assumptions are for the mode of transmission used in this model, if any? Since we can’t confirm the actual mode of transmission currently, I could see how a model like this could help narrow it down. Until we understand the actual mode(s) of transmission, I don’t see how we could come up with a viable solution (example - it’s maternal and we reduce population 99% but now we have 100% positive population or it’s environmental and remove all deer, but in 10 years the new population has the same number of positive animals).

My understanding is we currently can’t prove cwd can infect humans, using the same models that have been proven to show BSE can. That is good news!

No problem, I didn't realize that article is behind a paywall, but if anyone wants to see it in it's entirety, I can send it over. It's hard to break into the academic space when the models might as well be a foreign language number 1 and number 2 sometimes they're behind paywalls so I don't blame anyone that is not in the academic space for not delving into it.

They don't explicitly lay the mechanism out. We aren't sure what the primary transmission mechanism is but indirect transmission like feeding in the same spot after an infected deer is one of the really big concerns. In the whitetail world, this could be through the use of a licking branch where animals use that as a means of communication. I think this model likely accounts for both direct and indirect methods given they're only modeling the spread which could contain both direct and indirect transmission. That is an important distinction to make when it comes to management scenarios, but in this case they're likely accounting for both.

It's tough with CWD because it is not a fully density dependent disease, but it is also not frequency dependent, it's kind of in between from my understanding. However, because there is this component of indirect transmission, while holding the prevalence of CWD constant, the larger the number of deer in an area, the more prions are going to be found in the soil. This kind of accumulation in the soil is a major concern and is likely behind why it seems as though removing animals can lower the prevalence levels. As you remove those animals, you are removing positive individuals which over time lowers the amount of prions present in the environment itself. Similarly, we aren't sure how likely it is for an infected doe to transmit to her fawn yet, but given they interact consistently after birth with nose-to-nose contact, it is likely high.

We all definitely are still searching for a perfect management solution, but because of how it transmits and the weakness of the density-dependence, it is a really hard problem to deal with. I work with one of the authors on that paper consistently and I know there are new modeling efforts coming out soon that have some management recommendations for the future but I am not sure when that paper will be coming out. It is a large modeling effort that contains data from multiple midwestern and eastern states.

 

[elkhunter505]

Not intending to single you out specifically, but your comment was short and to the point…


How do the throw-out-the-meat guys rationalize handling a positive carcass before you have a test? If you’re willing to toss the edible portions, that carry very little if any prions, how do you go about caping, deboning, boiling skulls, etc, which can/likely do expose one to far more prions?

I’ve read at least one study the prions can be ingested via aerosol. Are you guys not scared of breathing them in when caping or boiling?

Are you sure the skull you hang in your house is completely prion free?

Are you guys packing a hazmat suit into the backcountry?

Tough for me to rationalize throwing out the meat but being perfectly fine with handling all the parts and pieces that actually contain prions in the meantime.

This is a solid question. I wear nitrile gloves whenever I process animals in the field so unless I am cutting myself and then leaving my hand in the meat, I feel good enough about it given the current research.

When it comes to skull and brain matter stuff, I am not sure how I would handle it yet as I haven't had an animal test positive yet, but what has been recommended to me by someone that works on CWD consistently if I wanted to keep a skull is to boil the skill, double bag all the water that was used for the boil and dispose of it in the class II landfill near me. When/If that concern arises, I will have to think more about whether or not I am going to keep the skull or get rid of it (saw the antlers off if it is a male). If I didn't live in a place where I had cervids in my backyard consistently, I would likely feel okay with it since it will dissipate in the soil over time but it is a valid concern and a valid question. I just haven't had to make that choice or decision yet. I do euro mounts for friends and I require them to test their animals, partly for science and partly for my own peace of mind. I'd likely turn away anything that came up positive and maybe recommend someone with beetles for that problem. Similarly, I might do the same for my own kill if it were to come up positive.

 

[RockAndSage]

Can’t prions be denatured via basic steam sterilization? I have seen multiple sources cite utilizing elevated temperatures and time is acceptable (much below what an incinerator is run at).

The time factor is important, as is pressure. Longer and higher pressure, the lower temperatures you can get away with.

 

[wapitibob]

Every Deer is going to die, most will die from cars, predators, winter or hunters before CWD kills them. If that weren't the case, WY and CO, which have had cwd for almost 40 years, wouldn't have any Deer left in their states.
Killing off all the Deer isn't going to solve anything, prions are still in the ground. Statewide, WY is hovering around 12-14% so it appears there is some natural immunity. Maybe leave them alone, worst case, it wouldn't end up any different than killing them all off.

 

[Speaks]

It sucks that to test in WI you need to send in the head.

 

[Billy Goat]

1800C or 1800F?

I was speaking in Celcius. Hence the C. 1000 Celsius is 1832 fahrenheit.

While I dont know for fact. I doubt they are operating an incinerator at Ti smelting temp of 1800c or 3200f.

Get out of here with your Commie Celsius and Mils.

 

[elkhunter505]

It sucks that to test in WI you need to send in the head.

I did not know that was the case in WI. I like how they do it here in MT with check stations you can go through and have them do it. Kind of fun and old timey feeling to shoot the shit with the biologists and any other hunters that happen to be there when you go through.

 

[ScreamingPotato]

I did not know that was the case in WI. I like how they do it here in MT with check stations you can go through and have them do it. Kind of fun and old timey feeling to shoot the shit with the biologists and any other hunters that happen to be there when you go through.

Same in Texas there's check stations in certain places, some areas are mandatory and some have dropped to voluntary. I don't go out of my way to test anything because the prevalence isn't terribly high here but if there's a check station on the way home I'll absolutely stop in. It takes them maybe 5 minutes to get the lymph nodes out and it's always fun to BS with the biologists.

 

[waspocrew]

Not intending to single you out specifically, but your comment was short and to the point…


How do the throw-out-the-meat guys rationalize handling a positive carcass before you have a test? If you’re willing to toss the edible portions, that carry very little if any prions, how do you go about caping, deboning, boiling skulls, etc, which can/likely do expose one to far more prions?

I’ve read at least one study the prions can be ingested via aerosol. Are you guys not scared of breathing them in when caping or boiling?

Are you sure the skull you hang in your house is completely prion free?

Are you guys packing a hazmat suit into the backcountry?

Tough for me to rationalize throwing out the meat but being perfectly fine with handling all the parts and pieces that actually contain prions in the meantime.

That's a great question and really would make you think about the whole process. Some of that would have to do with the prevalence of CWD in the unit you hunt. If it had a relatively high prevalence, then I'd be much more likely to take precautions (gloves while processing, disposable blades, etc.).

Not everyone processes their own animals. Some will only gut in the field and then take it to a butcher shop for processing. Some of these shops offer taxidermy, so the hunter never skins, capes, cuts a skull cap or takes the head off the vertebral column.

I'm a surgeon and part of the precautions of my job is to basically assume that all my patients have a Hep C, Hep B, HIV, etc. I wear the necessary personal protective equipment during procedures because exposures can and will happen. I've only had one needlestick during surgery so far over the last 7 years, but it's not a fun experience waiting for labs to confirm the patient didn't have any blood borne pathogens.

Is it likely for me to contract CWD? From the sounds of it, highly unlikely. However, I'm not going to willingly consume meat from an animal confirmed to have CWD.

 

[elkhunter505]

Every Deer is going to die, most will die from cars, predators, winter or hunters before CWD kills them. If that weren't the case, WY and CO, which have had cwd for almost 40 years, wouldn't have any Deer left in their states.
Killing off all the Deer isn't going to solve anything, prions are still in the ground. Statewide, WY is hovering around 12-14% so it appears there is some natural immunity. Maybe leave them alone, worst case, it wouldn't end up any different than killing them all off.

No one is saying that we should kill all the deer. One of the only reasons that prevalence levels stay low is through harvest. Without that harvest, prevalence would likely increase. Until someone presents me with valid peer-reviewed research about genetic natural immunity, I am going to treat it as though it is like a slow version of rabies where no cervid that comes into contact with the prion survives given that they don’t die from predation, cars, etc. before symptom onset (obviously bats and opossums have immunity to rabies but you get my drift). It would be massive news and a major win if anyone was able to prove there are animals that survive it and I will anxiously await that day. At this point given our knowledge of other TSEs, I am going to error that they’re dying at a 100% rate similarly to what we see with mad cow and CJD.

 

[Laramie]

CWD is extremely scary. I firmly believe people should stop hunting in areas where there have been positive tests at any point in history.

Ill also add, if anyone has an elk or deer that tests positive, please send me a pm. I'll gladly "dispose" of it for you.

 

[IAm_Not_Lost]

Be careful with this one. Even the scientists studying CWD acknowledge there hasn't been a documented case of transmission. That's not the point. Many things that never infected us before have evolved to do so. Prions evolve more quickly than many other organisms, so the worry isn't that they DO, it's how easily they MIGHT. Prions crossing the species barrier has already been observed in lab settings, and we've watched the same thing happen in the wild with fungal and bacterial infections as well. And bear in mind, we currently have NO treatments for these diseases.

The goal here is to close the gate before the horse is out, not wait and say "whoops, we knew this was a possibility, but did nothing, sorry folks..."

If you saw a hole in a wall that said "cows that stick their tongues in here often die of a terrible disease, but it hasn't been shown to kill a human yet..." would you stick your tongue in there?

Not sure if you read the post you quoted, or my full response, but I note that the recommendation is due to the theoretical risk it could adapt in the future. I also note later in my full post that I would follow the recommendation if my deer specifically came back positive for CWD due to that.

With that said, there are a TON of things that we do that could theoretically lead to future risk, illness, or adaptations, that we do anyways because as of right now there aren’t any immediate consequences. So, speaking frankly, the remote and - as of right now - unheard of transmission of CWD to humans is very far down the list of the risky things we as humans do every day.