A "ZOMBIE disease" that has killed thousands of deer in the US could soon infect humans in a chilling echo of Mad Cow Disease.
Chronic Wasting Disease (CWD) has swept across 22 states in the US and health experts fear it could mutate and jump the species barrier.
Mark Zabel, an immunologist at Colorado State University, told Colorado Public Radio that CWD is a newly discovered condition and may evolve rapidly, adding: "which leads us to believe that it's only a matter of time before a CWD prion (faulty protein) emerges that can do the same thing and infect a human".
Mad Cow disease emerged in the UK in the mid-1980s after cattle ate bone meal of sheep infected with scrapie, a similar brain-wasting disease.
The disease then made the jump to people through infected beef products, causing a new variant of Creutzfeldt-Jakob Disease (CJD).
Both CJD and CWD are deadly neurological disorders - transmissible spongiform encephalopathies (TSE) - that affect the brains and nervous system of many animals, including humans.
Scientists believe something similar to the CJD outbreak could happen should a hunter eat an infected deer.
Canadian researchers found that monkeys contracted CWD after eating a deer with the disease - the first time the disease has been shown to spread to a primate through meat.
Matt Dunfee, head of the Chronic Wasting Disease Alliance in Fort Collins, Denver, told the News Observer: "While most research shows there's a robust species barrier, this recent study showed that barrier might not be quite as robust as we once thought."