Online videos of crazed deer crashing through the American countryside are racking up views online. They have the deer version of BSE – Chronic Wasting Disease, or CWD - and it's now spread to northern Europe too. Scientists are worried.

History repeats itself as hunters speculate on the origin theories of this deer prion disease. The US government insists people are safe, but conspiracy theories about a hoax or cover up are starting to spread online.

Written, presented and produced by Lucy Proctor