WNS Spread Prediction Paper

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WNS Spread Prediction Paper

Postby cavergirl » Apr 30, 2013 2:48 pm

The link should lead you to a newly published masters thesis by Christy M. Ihlo of Duke University. The paper compiles a lot of data in an attempt to predict the future of WNS in North America.

http://dukespace.lib.duke.edu/dspace/bi ... sequence=1
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Re: WNS Spread Prediction Paper

Postby PYoungbaer » Apr 30, 2013 3:22 pm

A word of caution:

I read this paper the other day, but chose not to post it on the NSS' WNS web page for a couple of reasons. This is a Master's Level thesis, submitted as part of the student's requirements, and put forth by the Duke University press for its library. It is not a peer-reviewed document, and has not been published in a scientific paper. Frankly, we don't know if it was accepted. It is only due to the ubiquitousness of the Internet that we have access to this.

In contrast, the USGS - a taxpayer-funded agency, just published another study, peer-reviewed, predicting the Indiana bat would be wiped out in most of its range, but we can't access the full paper, only the abstract, unless we pay a fee of $31.50.

That said, I personally found this to be an excellent paper, by and large. It will likely be referenced by land managers, particularly in the West, as they look to prevent WNS from arriving. The ARC GIS maps are quite informative. However, I do have some issues: 1. species diversity in a region does not correlate with species density; 2. no mention of decon as a strategy; 3. no discussion of dose load necessary for infection (MOI), which results in the perception that ANY introduction of spores, no matter how small the number, results in infection. That is simply still unknown; 4. reference to John Gassett's claim that Kentucky did well with private landowners closing their caves - my memory says they got about 80 out of thousands; 5. no exclusion of sea caves in California.
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Re: WNS Spread Prediction Paper

Postby tncaver » Apr 30, 2013 7:19 pm

The only flaw I see with this thesis is that it seems to base most of its predictions on the proximity of human cave access via
proximity of airports and roads to caves. The thesis seems skewed toward human transport of the disease and tends to ignore some bat to bat transmission scenerios. Does she not realize that humans go everywhere regardless of roads and airports and that GD could have already reached every bat cave in the continental US long ago if humans were the vector? Why is it that everyone who conducts these studies continue to ignore the obvious? GD and WNS have not showed up everywhere in the continental US. If humans were the vector, that surely would have already happened a long time ago.
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Re: WNS Spread Prediction Paper

Postby wyandottecaver » Apr 30, 2013 8:49 pm

"This study uses little data to create reasonable results"

I think the authors own words describe this the best. It is in fact a pretty good student MS Thesis. As an authorative and illuminating study of WNS infection and transport it was...not. Like Peter I thought the GIS was interesting, but in examining the methods it tended to greatly oversimplify or skew real world expectations. Interestingly, while some of her reasoning was badly flawed such as using # caves regardless of whether they had bats as a direct measure of susceptability...many actually ended up producing a reasonable end result. It was overall, a good summary of previous work with a lot of holes. Some were legitimately hers, but many were actually the result of her cited sources like Boyles.

I thought she actually correctly identified the OK north TX corridor as the best possible chance to stop WNS at least in the short term. I also think she did a good job of addressing the shortcomings of the work in the end. My first impression issues were:

largest issue is that as a predictor you should NEVER use existing data to weight the model, only to validate the results. therefore since the model was engineered for known variables in known cases the predictions for the west seem reasonable even though the variables are all actually quite different.
Did you know that closing caves eliminates the possibility of human transmission? :doh:
I'm not sure I would characterize the entire Eastern US bat population as "decimated" but thats minor.
statement that since spores have wider temp tolerance temp is not important for transmission...then uses temp as a main variable. Also, overlooks probable differing transmission scale between active GD and Spores in bat-bat.
The perpetuation of bats as insect control mythology really annoys me. Bugs have LOTS of predators and thinking the loss of bats over a 4-6 year span in an area will result in plagues and economic devastation is pure popycock.
Using #caves as a direct measure is a failure of logic and in fact you would expect more caves/county to disperse bat populations resulting in lower susceptability. Vermont is a good case for concentrated populations vs Kentucky.
Using surface temp instead of cave humidity was understandible given the data available but likely skewed the results...a lot. The West is in general a very dry place.
bats moving to entrances to collect passive warmth from the sun I found..... amusing.
Similiarly, bats drinking in winter has been going on a loong time before WNS.
WNS has evolved to be less deadly? in 7 years? really? Possible I suppose.
Using accessability by transport rather than actual caver activity.
# of species/site county should decrease values...monocultures are far more vulnerable and while more species might increase transmission pathways they also represent barriers (if imperfect ones) to transmission between species.
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Re: WNS Spread Prediction Paper

Postby GroundquestMSA » Apr 30, 2013 9:33 pm

My internet connection won't allow me to actually read this paper, but one of the objections voiced by both tncaver and wyandottecaver seems unfair.

wyandottecaver wrote:Using accessability by transport rather than actual caver activity.


tncaver wrote:Does she not realize that humans go everywhere regardless of roads and airports and that GD could have already reached every bat cave in the continental US long ago if humans were the vector?


It seems that to a large extent accessability = "actual caver activity." While some humans may "go everywhere regardless of roads and airports," a lot more of them stick to caves that are easy to access. Indeed, the surest way, I think, to find virgin caves, is to find an area of karst landscape as far from a road as possible, and go there. I don't know what point the author is trying to make with this argument, but if she is assuming that humans are spreading WNS, then it would certainly be justified to predict that its arrival would firstly occur near easily accessed areas. Until I can get to an adequately modern connection to the outside world, let me know if I'm misunderstanding.
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Re: WNS Spread Prediction Paper

Postby tncaver » May 1, 2013 6:43 am

GroundquestMSA wrote: snip

wyandottecaver wrote:Using accessability by transport rather than actual caver activity.


tncaver wrote:Does she not realize that humans go everywhere regardless of roads and airports and that GD could have already reached every bat cave in the continental US long ago if humans were the vector?


It seems that to a large extent accessability = "actual caver activity." While some humans may "go everywhere regardless of roads and airports," a lot more of them stick to caves that are easy to access. snip: I don't know what point the author is trying to make with this argument, but if she is assuming that humans are spreading WNS, then it would certainly be justified to predict that its arrival would firstly occur near easily accessed areas.snip:


Consider this...there are lots of bat caves in the Southeast that ARE close to roads and have easy access to humans. One primary example is Ellison's Cave Georgia, which has been a major caving destination before, during and after WNS was
found in New York. Yet, it took seven years for WNS to make it's way there. If cavers were spreading WNS, one would surmise that Ellison's Cave would have contracted the disease a long time ago. Ellison's is one of the most popular caves in the Southeast. Cavers have always been capable of flying or driving from all over the country to get to Ellison's Cave and
intermingling on caving trips. It would seem that if cavers were spreading WNS, it would have shown up in Ellison's years ago and then spread around all over the country by so many cavers who were on trips together at the same time in the cave. That did NOT happen. Cavers could hike from New York to Ellison's faster than WNS arrived there.
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Re: WNS Spread Prediction Paper

Postby PYoungbaer » May 1, 2013 10:49 am

wyandottecaver wrote:I thought she actually correctly identified the OK north TX corridor as the best possible chance to stop WNS at least in the short term. I also think she did a good job of addressing the shortcomings of the work in the end.


I agree. That OK/TX corridor is easily viewed in her graphics, and makes sense. Your other numerous points are all well-taken. I didn't want to get into a full litany, but simply point out that this thesis should not given the same scientific deference as a peer-reviewed professional paper. Still, it's a decent informative student paper.
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Re: WNS Spread Prediction Paper

Postby Tlaloc » May 1, 2013 12:58 pm

I find it interesting that the methodology identified Teton County, Wyoming as a likely place for WNS. This is apparently because of the large number of caves. Almost all of these are crappy little groat holes and they're at high altitude where it's too cold for bats. The same can be said for areas in Montana. Bats are generally absent in Alpine caves.
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Re: WNS Spread Prediction Paper

Postby GroundquestMSA » May 1, 2013 4:59 pm

Tn - I'm not saying that WNS is caver spread, and if that is what the author of this paper is claiming then I can't agree. I'm only saying that caver traffic is greatest in easily accessible areas.
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Re: WNS Spread Prediction Paper

Postby tncaver » May 1, 2013 5:54 pm

GroundquestMSA wrote:Tn - I'm not saying that WNS is caver spread, and if that is what the author of this paper is claiming then I can't agree. I'm only saying that caver traffic is greatest in easily accessible areas.


Agreed.
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Re: WNS Spread Prediction Paper

Postby Extremeophile » May 2, 2013 10:02 am

Tlaloc wrote:Bats are generally absent in Alpine caves.

I'm not sure this is a widely accepted fact. I find that many people define alpine somewhat broadly. We have very few caves in Colorado that are truly alpine, i.e. above tree line, which is 11,500-12,000' for us. We have many sub-alpine caves at elevations between 10,000-10,500 feet with internal temperatures below 40F that are used by bats. Regardless, I agree that there is little correlation between the number of cave entrances and the number of bats.
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Re: WNS Spread Prediction Paper

Postby wyandottecaver » May 2, 2013 5:34 pm

groundquest,

the issue with her methodology for access was that she used transportation systems in general including airports to "weight" the expected vulnerability geographically. Thus the presence of an airport, interstate, or dense road network alone counted.

While I, like TN disagree with the logic it was used for (airports dont increase vulnerability to cavers per se), which was focused at individual people carrying spores, it could actually end up being useful as the most likely human transport scenario in my opinion is one where an infected bat is transported via commercial means...most likely by an airport or interstate.... :doh:
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