If you're a hunter or eat wild-caught game (deer, elk, moose, reindeer), then you should be concerned with chronic wasting disease (CWD). Chronic wasting disease is an always-fatal prion disease similar to "mad-cow disease" (bovine spongiform encephalopathy) in cattle.
In chronic wasting disease there is a long incubation period, followed by the brain become progressively like a sponge - riddled with holes, along with deterioration in brain function, behavioral changes, and eventually death. A horrible slow death. There are no treatments or vaccines.
It turns out that chronic wasting disease is slowly spreading and infecting wild game across the United States (26 states) and 3 Canadian provinces. [Also detected in Finland, Norway, South Korea, and Sweden.] The concern is that this disease will jump to humans, especially in people who eat contaminated meat.
A research center monitoring the situation and publishing information and research on its site is CIDRAP (Center for Infectious Disease and Policy). Make sure to look at the Tweets (Twitter).
One scary thing about CWD is that once it gets into the soil, it stays there for years, and high heat, disinfectants, and radiation don't kill it. Yikes! Dr.Zabel at the Colorado State Univ. Prion Research Center suggested a few years ago that controlled burns (fires) of infected fields or areas could eliminate the prions left behind by infected animals (from animal mucus/saliva, urine, and feces, and decaying carcasses) on plants and soil.
An article with advice for how hunters can protect themselves, and a map of where CWD is found in the US.: 5 Ways Hunters Can Prevent Spreading Chronic Wasting Disease
Here is some of what CIDRAP says on their site about CWD:
Chronic wasting disease (CWD) is a prion disease that affects several cervid species: deer, elk, reindeer, sika deer, and moose. CWD was first identified in 1967 in a captive mule deer living in a Colorado research facility. In 1981, CWD was detected for the first time in a wild cervid. Since these initial detections, CWD has been identified in 26 states and three Canadian provinces. It has also been detected in Finland, Norway, South Korea, and Sweden.
CWD is believed to be transmitted horizontally (i.e., animal-to-animal contact) through infectious bodily fluids such as saliva, urine, and feces. Once excreted into the environment, CWD prions can persist for years and withstand extremely high levels of disinfectants such as heat, radiation, and formaldehyde. CWD prions also are capable of binding to certain plants, with the ability to be transported while still remaining infectious. CWD is increasing in cervids as more animals come into contact with infectious prions, usually via direct contact with an infected cervid and its bodily fluids, although viable CWD prions in the environment can also infect animals. ...
Since CWD is now an established wildlife disease in North America, proactive steps, where possible, should be taken to limit transmission of CWD among animals and reduce the potential for human exposure. Although CWD has not yet been found to cause infections in humans, numerous health agencies have taken the stance that people should not be consuming CWD-positive animals. Since 1997, the World Health Organization has recommended that agents of any prion disease should not enter the human food chain. Likewise, the US Centers for Disease Control and Prevention, Health Canada, and multiple provincial and state health and natural resources agencies recommend that people should not consume the meat of an animal found to be positive for CWD.
Given the typical ten year or longer incubation period of prion-associated conditions, improving public health measures now to prevent human exposure to CWD prions and to further understand the potential risk to humans may reduce the likelihood of an event like bovine spongiform encephalopathy (BSE). In BSE, also known as "mad cow" disease, some British officials in the 1990s declared there was no risk of transmitting BSE prions through the consumption of contaminated beef, only to confirm related human cases of a similar prion disease in the ensuing years.