OK.So, a known method of spreading the disease is shipping deer around the country. Why would we enable the spread with so much at stake?If this disease is found in nature,why is it not reported in those states with large deer populations outside these disease areas?Surely hunters or others spending time in deer habitat would have reported it.Here in PA,there are pastures shared by sheep and deer and in my 50 years of deer hunting I never read or heard of infected deer.If I were a betting man I would bet that researchers experiments created this disease.
I doubt that research experiments created CWD. From my understanding it is caused by a prion which is an improperly folded protein. It is a type of spongiform encephalitis, which mad cow is also. Spongiform encephalitis is a naturally occurring thing. Have you ever heard of Creutzfeldt Jacobson Disease in humans (CJD)? It is caused by prions and is like mad cow disease, only it is in humans. The misfolded proteins or prions can occur naturally in all populations. It is rare, but can happen when proteins are made in the body and fold in a random improper manner. It can also be genetic instead of random, stemming from an allele that codes for improper protein formation.
For one animal to get it from another animal there has to be a transfer of the prion from one to another, so ingestion is one way that prions can transfer from animal to animal. However since deer are not carnivores I doubt that that is how they spread. Generally it is spread through the ingestion of infected tissue, and since it effects the brain this means eating brains. There are cannibalistic cultures where spongiform encephalitis is more common than the rest of the world, simply because they eat the brains of people. Prions are
thought also be transmitted through blood, again a possible vector of transmission during fighting. However "catching" prions is not like catching a virus when someone coughs, or bacteria from a dirty surface. However the prions that cause CWD may have another transmission vector that is unique to CWD that I have not heard about yet, but the above is based on the general transmission of prions as taught in biochemistry. It is my understanding that the mad cow outbreak in England was because of the incorporation of animal protein in feed rations (using the parts of a cow that were not eaten in feed to boost the protein numbers).
Now this is just a guess of mine, but I feel like the reason that CWD is seen more in captive deer is that it generally takes a large chunk of time before symptoms develop. In cows it can take as long as 8 years (but generally shows itself in 4-5 years) for an animal that has prions to exhibit mad cow disease. Now in the wild where there is predation the chance for an animal to be infected is already low, combine that with a possible long "incubation" period, and the animal will probably be eaten before it shows symptoms. Now take away the predators and prolong the deer's life so he becomes trophy size, and you may have allowed the disease enough time to impact the deer's brain to the point of showing symptoms. Again this is just a theory of mine, but it seems plausible.
Again this is my understanding based on what I was taught in biochemistry, and yes I did pretty well in it, lol. But knowledge on the subject of prions may have changed since then