Fact Check: Is CWD harmful to humans?

Is Chronic Wasting Disease (CWD) Harmful to Humans?

Introduction

The claim that chronic wasting disease (CWD), a prion disease affecting deer, elk, and moose, poses a risk to human health has garnered attention in recent years. While there is currently no direct evidence of CWD transmission to humans, concerns persist regarding its potential zoonotic risk. This article examines the available research and expert opinions on the matter, highlighting the complexities and uncertainties surrounding the claim.

What We Know

1. CWD Overview: CWD is a transmissible spongiform encephalopathy (TSE) that primarily affects cervids. It is characterized by neurological degeneration and is fatal to infected animals 6.

2. Species Barrier: A recent study conducted by the National Institutes of Health (NIH) suggests that there is a substantial species barrier preventing CWD from transferring from cervids to humans. The study utilized a human cerebral organoid model and indicated that the likelihood of transmission is low 1.

3. Mixed Evidence: Other studies have reported mixed results regarding the zoonotic potential of CWD. For instance, while some in vitro studies suggest that the species barrier is not absolute, epidemiological studies have not shown any confirmed cases of CWD transmission to humans 25.

4. Epidemiological Concerns: The increasing prevalence of CWD in cervid populations raises concerns about potential exposure to humans, especially in regions where hunting and consumption of venison are common. Some researchers argue that the risk of a new form of human prion disease could arise, similar to the transmission of bovine spongiform encephalopathy (BSE) to humans 37.

5. Current Guidelines: Health organizations, including the Centers for Disease Control and Prevention (CDC), recommend that hunters avoid consuming meat from infected animals and take precautions when handling carcasses 69.

Analysis

The evidence regarding the risk of CWD to humans is nuanced and requires careful consideration of the sources:

• NIH Study: The NIH study is a primary source that provides a strong argument for the low risk of CWD transmission to humans. However, it is essential to note that this research is based on a specific model and may not fully capture the complexities of real-world exposure 1.

• Mixed Results in Research: The mixed results from various studies indicate that while there is a strong species barrier, it is not absolute. This uncertainty is echoed in the literature, where some studies suggest potential transmission pathways under certain conditions 25. The reliance on in vitro studies raises questions about their applicability to real-life scenarios.

• Epidemiological Studies: The lack of confirmed human cases linked to CWD is a critical point. However, the potential for future zoonotic transmission cannot be dismissed, especially given the historical context of other prion diseases 34.

• Potential Conflicts of Interest: Some sources, such as state wildlife agencies, may have an interest in downplaying risks to promote hunting and wildlife management practices. This potential bias should be considered when evaluating their claims 9.

• Need for Further Research: Given the evolving nature of CWD and its spread, ongoing research is crucial to monitor any changes in its zoonotic potential. Studies that explore long-term exposure effects and the mechanisms of prion transmission would be particularly beneficial.

Conclusion

Verdict: Mostly False

The claim that chronic wasting disease (CWD) poses a significant risk to human health is assessed as "Mostly False." The primary evidence supporting this verdict stems from a study by the National Institutes of Health, which indicates a substantial species barrier that likely prevents CWD from transmitting to humans. However, the evidence is not definitive, as mixed results from various studies suggest that while the risk appears low, it is not entirely absent.

The context surrounding this claim is crucial; while there have been no confirmed cases of human transmission, the increasing prevalence of CWD in cervid populations and the historical precedent of other prion diseases raise valid concerns. Additionally, potential biases in reporting from wildlife agencies and the need for further research highlight the complexities of this issue.

It is important to acknowledge the limitations of the current evidence. The reliance on specific models and in vitro studies may not fully represent real-world scenarios, and ongoing research is necessary to clarify the zoonotic potential of CWD.

Readers are encouraged to critically evaluate information regarding CWD and its implications for human health, considering the nuances and uncertainties that exist in the current body of research.

Sources

1. NIH study shows chronic wasting disease unlikely to move from animals to people. National Institutes of Health. Link
2. Exposure Risk of Chronic Wasting Disease in Humans. PubMed. Link
3. Chronic Wasting Disease and Potential Transmission to Humans. PubMed Central. Link
4. Chronic Wasting Disease: State of the Science. PubMed Central. Link
5. Chronic wasting disease: Emerging prions and their potential risk. PubMed Central. Link
6. About Chronic Wasting Disease (CWD). Centers for Disease Control and Prevention. Link
7. Chronic wasting disease - PMC - National Center for Biotechnology Information. Link
8. Lack of Transmission of Chronic Wasting Disease Prions to Humans. CDC. Link
9. Human Health and CWD | Virginia DWR. Virginia Department of Wildlife Resources. Link
10. NIH researchers never said there is no risk of CWD. CIDRAP. Link