This post was originally published at Mind the Science Gap on Nov. 29, 2012.
In early October a deer tested positive for Chronic Wasting Disease for the first time in Pennsylvania. The positive result, which was found in a farm herd, resulted in the quarantine of all the deer on the property. Earlier this month, a deer escaped the quarantine and was running free in Pennsylvania. Two days ago that deer was shot and killed to prevent further disease transmission. That doe is still undergoing testing to determine if she was infected. As a result of all of these events unfolding, Pennsylvania has swiftly put plans into action. Chronic Wasting Disease (CWD) is nearly impossible to eradicate once it establishes itself in a population, and in order to save PA’s deer herds, they needed to act fast.
Chronic Wasting Disease is endemic (established in wild populations) in Colorado and Wyoming. It has also been reported in wild herds in Illinois, Kansas, Maryland, Minnesota, Missouri, Nebraska, New Mexico, New York, North Dakota, South Dakota, Texas, Utah, Virginia, West Virginia, and Wisconsin. CWD has been found in captive herds in other states, such as Iowa. States with no confirmed cases often have CWD task forces and policies to prevent introduction of the pathogen. For example, Washington recently began requiring hunters returning from CWD-endemic areas to undergo testing and processing to remove infectious material.
CWD is a type of transmissible spongiform encephalopathy (TSE), a group of disease that includes Bovine Spongiform Encephalopathy (Mad Cow), Scrapie (a disease commonly found in sheep), Creutzfeldt-Jacob disease (a neurodegenerative disease in humans), and Fatal familial insomnia (a disease where protein misfolding results in insomnia which progresses to delusions and eventually death). TSEs are all caused by a pathogenic organism known as a prion. Prions are rather unique in that they are not a virus or bacteria, but a protein with an abnormal structure. These prions can be infectious and transmissible (like CWD and Mad Cow) or inherited (like the fatal insomnia). Continue reading