In the quiet vast forests and grasslands of North America, a silent but worrying phenomenon is unfolding: Chronic Wasting Disease (CWD). The condition, often called “zombie deer disease,” is spreading stealthily among deer populations, raising concerns among scientists, conservationists and the public.
This neurological disorder, characterized by numerous symptoms such as drooling, lethargy, stumbling and a blank stare, has now been detected in more than 800 deer, elk and moose samples in Wyoming alone, underscoring the magnitude and urgency of the problem.
At the heart of the CWD puzzle lies a peculiar culprit: prions.
Prions are misfolded proteins that can cause normal proteins in the brain to also misfold, leading to neurological degeneration. This unique characteristic makes prion diseases of particular concern as they are notoriously resilient and can persist in the environment for years, resisting traditional disinfection methods such as formaldehyde, radiation and combustion at extreme temperatures.
The spread of CWD poses significant ecological and potentially human health risks. Although there is no conclusive evidence that CWD can directly infect humans, the possibility remains a concern.
Prion diseases, such as Creutzfeldt-Jakob disease (CJD) in humans and ‘mad cow disease’ in cattle, have shown that they can cross the species barrier – with devastating consequences.
For example, the mad cow disease outbreak in Britain resulted in the slaughter of millions of cattle and led to 178 human deaths since 1995, attributed to the human variant of the disease.
Despite the lack of confirmed cases of CWD in humans, concerns remain due to several factors. First, studies have shown that prions responsible for CWD can infect and reproduce in human cells under laboratory conditions, raising the specter of possible transmission.
Second, people are already unintentionally exposed to potentially infected animals by hunting and eating them. Reports indicate that between 7,000 and 15,000 CWD-infected animals were consumed by humans annually in 2017, with projections indicating an annual increase of 20%.
In regions where the prevalence of CWD is high, such as Wisconsin, thousands of people may have unknowingly consumed meat from infected deer, underscoring the urgency of action to reduce the risks.
Furthermore, the inherent difficulties associated with detecting and diagnosing prion diseases in humans further complicate the situation. Unlike conventional infectious agents, prions do not induce an immune response, making them difficult to detect by conventional means. This poses a significant obstacle to early intervention and control efforts.
The potential of CWD to affect human health is not limited to direct transmission. The persistence of prions in the environment means that humans can also be exposed through indirect routes, such as contaminated soil, water and other environmental sources.
Given the resilience of prions and their ability to persist in the environment for extended periods, the long-term consequences of CWD on human health remain uncertain but deserve serious attention.
In addition to the immediate health concerns, the spread of CWD also poses significant environmental and economic risks. Deer hunting is not only a popular recreational activity, but also an essential source of livelihood for many communities.
The proliferation of CWD threatens to disrupt this delicate balance, potentially decimating deer populations and endangering food security in affected regions.
Furthermore, the ecological effects of CWD extend beyond deer populations and affect entire ecosystems. Deer play a crucial role in shaping vegetation dynamics (how plant communities change and evolve over time) through browsing and grazing.
And their decline could have cascading effects on plant communities, soil health and other wildlife species that rely on deer as a food source or habitat modifier.
Also in Europe
It is notable that although there have been no outbreaks of CWD in Britain, the disease was diagnosed in wild deer in Norway in 2016, marking the first cases of CWD in Europe.
This development underlines the potential for CWD to spread beyond its current range and emphasizes the need for international cooperation in monitoring and controlling the disease.
Addressing the many challenges posed by CWD requires a comprehensive and coordinated approach.
This includes strengthening surveillance and monitoring to track the spread of the disease, and implementing strict biosecurity measures to prevent onward transmission – such as controlling the movements of deer and elk populations, conducting regular testing to monitor the prevalence of diseases and promote responsible hunting practices to minimize the spread of diseases. the risk of transmission.
More research is also needed to better understand the disease’s transmission dynamics, its ecological effects, and its potential impacts on human health.
Ultimately, the specter of CWD underscores the interconnectedness of ecosystems and human health. By heeding scientists’ warnings and taking decisive action to limit risks, we can strive to protect both wildlife and human populations from the insidious grip of CWD and other emerging zoonotic diseases.
In doing so, we honor our commitment to protect the health and well-being of our planet and its inhabitants for generations to come.
Samuel J. White, Senior Lecturer in Genetic Immunology, Nottingham Trent University and Philippe B. Wilson, Professor of One Health, Nottingham Trent University
This article is republished from The conversation under a Creative Commons license. Read the original article.
