Chronic Wasting Disease

Chronic wasting disease (CWD) is a contagious neurological disease that affects members of the deer family. It causes erratic behavior and weight loss that results in death. It is part of a family of diseases that includes bovine wasting disease (mad cow disease) and scrapie, a similar disease that infects sheep. CWD affects elk, moose, and multiple deer species. Colorado has been one of the epicenters of CWD since its discovery in 1967.

Discovery, Description, and Spread

In 1967, a group of scientists working at the Colorado Division of Wildlife facility in Fort Collins discovered a captive mule deer behaving strangely. Before long, the deer had died. Scientists discovered it was infected with a new disease. Several more infected mule deer were later reported. Scientists knew little about CWD until 1978, when Elizabeth Williams, a researcher at the Wyoming State Veterinary Laboratory, determined it was caused by irregularly folded prions—certain proteins—within the deer.

Produced by all mammals, prions are normally used and then broken down within an animal’s cells. When these prions are irregularly folded, the organism’s cells cannot properly break down the protein. When the prions are not broken down, they build up in neural and lymphatic tissue, causing abnormal behavior. This behavior can include a loss of fear of humans, diminished social interaction, increased drinking and urination, and increased salivation. The buildup of prions eventually leads to the animal’s death. Infected animals may show no sign of the infection for up to seventeen months. Once infection sets in, the average survival time is a few months.

Since 1967, CWD has spread from captive populations in Colorado to free-ranging elk, moose, and deer in other parts of the country. The disease can be spread by blood, saliva, and feces. Most of the disease’s spread can be attributed to healthy animals eating the same plants as infected ones. The first case of the disease reported outside of Colorado occurred in Wyoming in 1979. Since then, the disease has spread to more than twenty US states and two Canadian Providences.

CWD in Colorado

Significant research on CWD has been conducted at Colorado State University. Since mad cow disease can mutate to affect humans, many of the studies deal with CWD’s potential to infect noncervid organisms. So far, scientists have infected cows, transgenic mice, and spider monkeys. However, the only instances of infection have been in lab environments. So far, there are no known cases of CWD being transmitted to a noncervid organism in the wild. Studies examining the potential transfer of CWD to humans have shown no conclusive evidence that the disease is a threat to people.

CWD has a significant impact on Colorado’s deer and elk population. In areas with dense cervid populations, up to 30 percent of the population can be infected. From 2003 to 2013 Colorado’s mule deer population has dropped by 36 percent. Colorado’s elk herds have also started to decline in some parts of the state.

Colorado Parks and Wildlife has attempted to manage the disease. In 2001, the Division of Parks and Recreation implemented a ten-year plan to prevent the spread of CWD. These efforts have been largely ineffective. Officials continue to conduct further research.

Chronic wasting disease has had a widespread impact on wildlife across North America. The history of this disease has only just begun. Colorado is ground zero.

Chronic wasting disease (CWD) is a contagious neurological disease. It causes erratic behavior and weight loss that results in death. CWD affects elk, moose, and multiple deer species.

Discovery, Description, and Spread

In 1967, a group of scientists at the Colorado Division of Wildlife discovered a captive mule deer behaving strangely. Before long, the deer had died. Scientists discovered it was infected with a new disease. Several more infected mule deer were later reported. Scientists didn't know much about CWD until 1978, when they discovered the disease was caused by irregularly folded prions—certain proteins—within the deer.

Prions are normally used and then broken down within an animal’s cells. When these prions are irregularly folded, the animal's cells cannot process the protein. The proteins build up. The buildup leads to the animal’s death. Infected animals may show no sign of the disease for months. Once infection sets in, the average survival time is a few months.

Since 1967, CWD has moved from captive animals to free-ranging elk, moose, and deer. The disease can be spread by blood, saliva, and feces. Healthy animals can get the disease when they eat the same plants as infected ones. The first case of the disease reported outside of Colorado occurred in Wyoming in 1979. Since then, the disease has been found in more than twenty US states and two Canadian Providences.

CWD in Colorado

Much of the research on CWD has been conducted at Colorado State University. Many of the studies deal with CWD’s potential to mutate and infect noncervid organisms. So far, scientists have infected cows, transgenic mice, and spider monkeys. However, the only instances of infection have been in a lab. There are no known cases of CWD being transmitted to a noncervid organism in the wild. Studies have shown no conclusive evidence that the disease is a threat to people.

CWD has a significant impact on Colorado’s deer and elk population. From 2003 to 2013, Colorado’s mule deer population has dropped by 36 percent. Colorado’s elk herds have also started to decline in some parts of the state.

Colorado Parks and Wildlife has attempted to manage the disease. In 2001, the Division of Parks and Recreation put a ten-year plan to prevent the spread of CWD in place. These efforts have been largely ineffective.

Chronic wasting disease has had a widespread impact on wildlife. The history of this disease has only just begun. Colorado is ground zero.

Chronic wasting disease (CWD) is a contagious neurological disease. CWD affects elk, moose, and multiple types of deer.

Discovery, Description, and Spread

In 1967, a group of scientists found a captive mule deer behaving strangely. The deer later died. Scientists discovered it was infected with a new disease.

Scientists didn't know much about chronic wasting disease until 1978. They discovered the disease was caused by irregularly folded prions. Those are certain proteins found in mammals.

Prions are normally used and broken down within an animal’s cells. When these prions are irregularly folded, the animal's cells cannot process the protein. The proteins build up. The buildup leads to the animal’s death.

Infected animals may not appear sick for months. Once the disease sets in, animals die within a few months.

CWD has moved from captive animals to wild elk, moose, and deer. The disease is spread through blood and spit. Healthy animals can get the disease when they eat the same plants as infected ones.

In 1979, the disease was found in Wyoming. Since then, CWD has spread to more than twenty states.

CWD in Colorado

Much of the research on CWD is being done at Colorado State University. Many of the studies deal with CWD’s potential to mutate and infect other types of animals. There are no known cases of CWD being transmitted to another type of animal in the wild. Studies have shown no evidence that the disease is a threat to people.

CWD has had an impact on Colorado’s deer and elk population. From 2003 to 2013, Colorado’s mule deer population has dropped by 36 percent. Colorado’s elk herds have also started to decline in some parts of the state.

Colorado Parks and Wildlife has attempted to manage the disease. In 2001, a plan was put in place to prevent the spread of CWD. These efforts have not worked well.