NOV 10, 2017 08:28 AM PST

Chronic Wasting Disease Prion Shedding in Deer

Chronic wasting disease (CWD) is a contagious neurological disorder that affects deer, elk, reindeer, and moose that leads to degeneration of brain tissue. Symptoms in infected animals include emaciation, abnormal behavior, loss of bodily functions, and ultimately death. CWD is a member of the transmissible spongiform encephalopathies (TSEs) which include scrapie and mad cow disease.

Chronic wasting disease (CWD) is a neurodegenerative disorder that affects deer, elk, reindeer and moose. It is caused by a misfolded protein known as a prion. Credit: Colorado State University

CWD can has been detected in animals in North America, Canada, Norway, and South Korea. As of September 2017, the CDC reported that at least 21 states in the continental US found CWD in free-ranging deer. While affected areas continue to expand, the overall incidence of CWD is relatively low.

Fortunately, there has been no reported incidence of CWD in humans however; studies have shown that it is possible for CWD to spread from infected deer or elk to non-human primates such as monkeys. The disease could potentially spread to humans through the consumption of contaminated meat or through contact with the brains or bodily fluids of CWD-infected animals. The World Health Organization advises it is important to prevent agents of prion diseases from entering the food chain.

Detection of prion diseases is difficult due to the nature of this atypical pathogen. CWD is caused by the misfolded form of a normal protein. As proteins are made within the cell, they fold into a specific configuration that allows them to perform a specific function. When proteins are misfolded, they are unable to perform their function, leading to disease.

A group of researchers from Colorado State University and the Alaska Fisheries Science Center used predictive modeling to discriminate the shedding of prions and the detection of prions in saliva. According to the authors of the study, this distinction is important for understanding the role of prion shedding in disease transmission as well as diagnosis of the disease. Sensitive detection methods are difficult for samples containing a high level of microbial diversity, such as saliva.

Their statistical analyses revealed that shedding of prions in saliva increases from the time the animal becomes infected. Shedding of prions can occur before the animal even shows symptoms of CWD which can occur for up to a year or more. Shedding was not influenced by the sex of the animal or by the specific genotype of the prion. Interestingly, authors of the study found that the source of the prion by which animals were experimentally inoculated played a large role in the quantity of prion shedding. Specifically, animals who were inoculated with prions from the saliva of CWD-infected animals shed more prions than those inoculated with brain tissue from CWD-infected animals.

This research provides insight into the horizontal transmission of CWD in animals as well as factors that influence prion shedding in the wild. More sensitive detection methods for better surveillance and diagnosis of the disease are warranted.

Sources: Chronic Wasting Disease Alliance, Journal of Clinical Microbiology, CDC

About the Author
  • I am a postdoctoral researcher with interests in pre-harvest microbial food safety, nonthermal food processing technologies, zoonotic pathogens, and plant-microbe interactions. My current research projects involve the optimization of novel food processing technologies to reduce the number of foodborne pathogens on fresh produce. I am a food geek!
You May Also Like
OCT 11, 2018
Microbiology
OCT 11, 2018
New Vaccine Protects Against Lassa Fever and Rabies
In Africa, Lassa fever is a significant threat to public health. It is a member of the same family of viruses as Ebola....
OCT 16, 2018
Videos
OCT 16, 2018
Can the Bacteria That we Carry Give us Special Powers?
The bacteria that we carry in and on our bodies can affect our health and well-being in many ways....
OCT 30, 2018
Drug Discovery
OCT 30, 2018
Combination of Drugs Extends Lifespan of C. elegans
In a study published in the journal Developmental Cell, a cocktail of pharmaceutical drugs were recently found to extend the life of the microscopic worm,...
NOV 07, 2018
Videos
NOV 07, 2018
The Threat of Neglected Tropical Diseases
Did you know that around one billion people suffer from a neglected tropical disease?...
NOV 19, 2018
Cell & Molecular Biology
NOV 19, 2018
How Mitochondria can Help the Cell Fight Pathogens
Some pathogens can get around out bodies' natural defense mechanisms. So our body developed a Plan B....
NOV 26, 2018
Health & Medicine
NOV 26, 2018
The Role of Clinical Lab Scientists
The clinical laboratory is the heart of any hospital or healthcare system. It is responsible for greater than 70% of medical diagnoses and decisions made b...
Loading Comments...