- In environmental news, UW-Madison scientists have
discovered chronic wasting disease prions in soil and water
where deer congregate.
According to a lead researcher in the discovery,
it's the first time the existence of prions in soil has
been demonstrated.
The discovery coincides with Governor Scott Walker's new
emergency rules that include requiring reinforced fencing
around deer farms, banning the movement of live deer from deer
farms in CWD-affected counties and a ban on moving whole deer
carcasses from such counties.
But prions in soil and water?
Could that be what has helped CWD spread to affect 53 of
Wisconsin's 72 counties?
UW-Madison Professor of Soil Science, Joel Pedersen,
helped lead the research.
He joins us now.
Thanks for being here.
- Good to be with you.
- So as to that question, could CWD prions in the soil be an
additional cause for the spread of CWD?
- We and others have for many years hypothesized that
environmental routes of transmission such as via soil
and water may contribute to CWD epidemics.
The relative importance of environmental routes versus
direct contact between an infected animal and unaffected
animal is not clear.
- So how would you describe, though,
this discovery made on the part of yourself and others?
- Well, as you said, it's the first time that prions
have been discovered in naturally-contaminated soils.
We found them at sites where deer congregate.
Whether they are at sufficiently high concentrations
to cause transmission and contribute to epidemics
is not clear at this time.
- Further research is ongoing on this though,
on your part and others across the country?
- Yes. - Yeah.
And so these mineral licks, where deer congregate,
would the same kind of numbers of deer congregate
at feeding or baiting sites
and cause the same kind of prions to enter the soil?
- Certainly any area where deer congregate has a potential of
shedding prions into the environment.
We are particularly interested in mineral licks because
these are locations where deer actually consume soil,
so the medium onto which they would shed the prions.
- So once the prions get into the soil,
what happens to them then?
I mean, are they washed away or washed into groundwater or...?
- Research-- excuse me.
Research conducted in my group indicates that
leeching into groundwater is not a significant cause for concern.
They certainly could attach to soil particles
and be washed off of a site.
There was a previous report of prions in a water sample
in Colorado in a watershed-draining CWD--
area with high incidence of CWD.
The degradation of prions in soil seems to be rather slow.
We don't have a good sense for how long it would take
for them to degrade.
- And what do scientists know about whether or not if there
are these CWD prions in soil, whether that could result in
transmission to other animals?
- There's certainly that potential,
but we don't have any -- to my knowledge,
no experiments have been done to address that.
- And what about, really, the big question,
transmission to humans?
- That, of course, is a question on many people's minds.
There is not conclusive evidence that
prions could transmit to humans at this time.
There is ongoing work in that effort.
And there is ongoing work in trying to understand that,
both in the National Institutes of Health and at universities.
- Because people really are kind of starting to sound
the alarm on that, aren't they?
- I don't think that-- again, we don't have any definitive
proof of transmission to humans.
And I hope to learn more about this next week when I'm at a
prion meeting where I think that some results that are relevant
to this question will be reported.
- We'll be looking for that as well.
What kind of reaction have you had to this discovery from
policymakers or regulators here in Wisconsin or elsewhere?
- Some interest, but I haven't had much contact with them.
- Given the results of this research,
what do you think should be done to limit these kinds
of congregations of deer?
- Well, certainly it seems that practices that cause deer to
congregate should be revisited in terms of whether we should
regulate that or not.
Our study, while showing that prions are present
in such places, again, does not answer the question
about whether transmission is significant at those locations.
- All right. Joel Pedersen, thanks very much.
- Thank you.