Chronic Wasting Disease Spreads Among North American Deer Populations
Scientists have identified Chronic Wasting Disease (CWD), also known as the “zombie deer disease,” within multiple North American deer populations. Of particular concern, the largest number of infected animals, with more than 800 samples found in deer, elk, and moose, was discovered in Wyoming, according to The Conversation.
Origins and Spread of Chronic Wasting Disease
First detected in Colorado in the late 1960s, CWD was initially found in captive deer and later in wild deer in 1981. The Centers for Disease Control and Prevention (CDC) reports that the disease has since spread to at least 31 states across the U.S., affecting various regions. Additionally, it is important to note that some states lacking extensive animal surveillance systems may have undetected cases of CWD. The disease has the potential to persist in the environment for long periods, with affected areas expecting further expansion.
Devastating Impact on Infected Animals
In depth studies published in the journal Annual Reviews reveal that CWD is a prion disease, where abnormal proteins misfold healthy brain proteins, leading to neurological damage. Infected animals may suffer from a series of debilitating symptoms, including drooling, lethargy, weight loss, stumbling, and vacant gazes. Significantly, up to a year could pass before infected animals display these symptoms. CWD affects animals of all ages, and some may succumb to the disease without exhibiting any signs. Currently, no cures or vaccines for CWD exist, according to the CDC. The disease appears to spread between animals through body fluids such as saliva, blood, urine, and excrement. Transmission occurs through direct animal contact or when animals encounter contaminated soil, food, or water sources. The CDC warns that once CWD infiltrates an area, it can spread rapidly within deer and elk populations.
Potential Human Health Risks Associated with CWD
Although no confirmed cases of CWD in humans have been reported, various prion diseases have crossed the animal-human barrier in the past. “Mad cow disease,” for instance, claimed the lives of millions of cattle and 178 humans since 1995, as reported by The Conversation. University of Texas Health Science Center findings, published in JNeurosci, found that CWD could infect human cells under specific conditions. Scientists hypothesize that the disease could spread to humans through the consumption of infected deer populations. Detecting and diagnosing prion diseases in humans poses significant challenges as prions do not engage the immune system, making it difficult to identify them using standard methods. Consequently, early intervention and disease containment become problematic.
Ecological and Economic Implications
Alongside health concerns, the spread of CWD poses additional risks. Deer hunting serves as both a widely enjoyed recreational activity and a vital source of food and income. Disruption of this delicate balance due to CWD could severely harm deer populations and compromise food security. Moreover, the effects of CWD are not limited to deer alone; these animals play a role in shaping plant growth and altering ecosystems over time. Consequently, a decline in deer numbers due to the disease may have a diverse impact on plants, soils, and other wildlife that depend on deer for sustenance or habitat.
Spread of CWD beyond North America
While the majority of reported CWD cases are found in the United States and Canada, instances of the disease have also been identified in other countries. These countries include Norway, Finland, Sweden, and South Korea. The CDC cautions that CWD may exist in countries with limited or weak animal surveillance systems.
Preventing the Spread of CWD
To curtail the spread of CWD, the CDC recommends specific guidelines for hunters in affected areas:
- Avoid shooting, handling, or consuming meat from deer and elk that appear sick, behave strangely, or are found dead.
- When dressing a deer, utilize latex or rubber gloves, handle organs as little as possible, and avoid using household knives or kitchen utensils.
- Stay informed about testing recommendations through state wildlife and public health guidelines.
- Consider testing deer or elk for CWD before consuming their meat.
- Opt for individual meat processing to avoid mixing meat from multiple animals in commercial processing.
- If an animal tests positive for CWD, refrain from consuming its meat.
While further research is necessary to fully understand and combat CWD, ongoing clinical trials investigating potential vaccines are taking place in Canada, as highlighted in a review published in Inder Science Online.
