Another threat to the food supply is chronic
wasting disease. This is a prion disease that
infects deer, elk and moose. And it's been
recognized as increasingly prevalent in these
animals. On this map of the US and Canada,
you can see numbers which indicate the years
that chronic wasting disease has been discovered
in these animals, so you can see it's been
found throughout the US, particularly in the
Midwest states. It's also been found in Canada
and more recently in South Korea and the graph
on the right shows you among total captive
and free ranging animals, the increase in
discovery of this affliction since 1965.
So there's been a steep increase since 1995.
So these animals develop a TSE essentially
very much like mad cow disease, they become
disoriented and eventually they die. This
is thought to be a threat to the food supply
in standing herds of elk and deer, you can
have 90 or 60% of the animals positive for
chronic wasting disease, prions and in wild
animals, up to 15% of randomly sampled animals,
seem to have these prion diseases. Now why
is this a threat to us, well many people hunt
deer and so this is making you at risk for
possibly being contaminated by a deer prion.
We don't know if deer prions can be transmitted
to humans, but if you listen to another more
advanced lecture on prion diseases, we'll
talk about some experiments that address that
Another potential issue with the human food
supply is that deer often contaminate pastures
in which there are cows that are used for
milk or for eating. So for example at night
the deer may go into the pastures and defecate
in the pasture, the feces of deer and urine
of deer has been shown to contain prions,
so the next day the cows may be contaminated
with that, and the prion may cross into cows.
So right now we're a little bit worried about
chronic wasting disease as it affects either
deer meat or beef.
So after listening to this, you're probably
very frightened about eating beef, but remember
it's a very rare disease, the TSE, so you're
probably okay, but also I hope that you
know the history of prion discovery. I hope
you understand what a prion is and what diseases
prions can cause. You should know the three
different kinds of prion diseases and you
should be able to assess why mad cow disease
and chronic wasting disease are threats to
the food supply.
Thanks for listening, I'm sorry if I scared you,
see you next time.