• Chronic wasting disease is an infectious prion disease which can affect five of the cervid species (whitetails, mule deer, elk, moose and reindeer). Prions are infectious proteins.

• Similar prion brain diseases have been around for decades, for example, Creutzfieldt Jakobs Disease in humans, which was first diagnosed in 1920.• CWD was first recognized in a captive mule deer herd, held for research in Colorado in the 1960s, but other cases could have occurred in Colorado and other areas before the disease was recognized. CWD currently has been detected in free and captive cervids in 24 states and three Canadian provinces. The disease is always fatal.• When a CWD-positive deer passes prions via mucous, urine or feces, the prions remain in that location for years. Some infected deer initially will show little effects, but as prevalence in the population increases that changes.In an eight-year study in Wyoming, 29 percent of sampled deer had CWD in 1999. In 2003, that had jumped to 32 percent; by 2010, the number was 43 percent. Overall, from 2003 to 2010, the deer population declined by 10 percent.• Pennsylvania has previously taken steps to isolate the disease. In deer management area 2, feeding and baiting have been banned; hunters may not use urine-based deer lures. It is also illegal to remove whole deer carcasses from the area; only the meat and skull cap (with high risk parts removed) may be taken out of the area.