Researchers detected evidence of chronic wasting disease prions in blood samples from free-ranging white-tailed deer, including some deer with no detectable prion deposits in other tissues. The discovery could help advance early detection—but important questions remain.
The Big Takeaway
Chronic wasting disease (CWD) can spread through deer populations long before infected animals show obvious symptoms. That makes detecting infections early a major challenge for wildlife managers.
In a 2026 study published in Scientific Reports, researchers detected CWD prion seeding activity in blood samples from 19 of 33 healthy-appearing white-tailed deer collected in regions where CWD was established. In three of those deer, the researchers detected prion activity in blood even though their tests found no prion deposits in the lymphoid or brain tissues examined.
The findings suggest that blood-based testing could eventually provide another way to detect CWD, potentially identifying some infections earlier than tissue-based tests.
But this was a relatively small study using a specialized laboratory technique. Blood testing also failed to detect prion activity in some deer whose tissues tested positive. The method is promising, but it has not yet been established by this study as a stand-alone diagnostic test for routine deer management.
What Did Researchers Study?
Devon J. Trujillo and colleagues investigated whether a specialized laboratory assay could detect CWD prions in the blood of naturally exposed, free-ranging white-tailed deer.
The study included 37 deer collected from four locations in the southeastern United States. Thirty-three came from areas where CWD was established:
- Arkansas: 11 deer
- Tennessee: 14 deer
- West Virginia: 8 deer
The remaining four deer came from Georgia, an area without detected CWD in the study’s sampling region. Those animals served as a comparison group.
Researchers collected blood and tissue samples to evaluate whether prion activity could be detected in the blood and how those findings compared with evidence of infection in other tissues.
How did the blood test work?
The researchers used a modified technique called lipase iron-oxide bead real-time quaking-induced conversion, or LIQ RT-QuIC.
Rather than relying on visible symptoms, this laboratory method detects seeding activity associated with abnormal prion proteins. The assay amplifies the signal from these proteins so that very small amounts can be detected.
Researchers examined buffy coat cells, the portion of blood that contains white blood cells and platelets. They also tested lymphoid tissues and the brainstem region known as the obex using laboratory methods that included RT-QuIC and immunohistochemistry.
This approach allowed the researchers to compare blood-test results with evidence of prion activity or accumulation in other tissues.
What Did the Researchers Find?
1. Prion activity was detected in blood from 58% of deer sampled in CWD-endemic areas
The blood assay detected prion seeding activity in 19 of the 33 deer collected from CWD-endemic areas, or 57.6%.
The detection rates differed among the three states:
- Arkansas: 4 of 11 deer, or 36.4%
- Tennessee: 11 of 14 deer, or 78.6%
- West Virginia: 4 of 8 deer, or 50%
All four deer sampled in the Georgia comparison area tested negative.
These results show that the assay could detect blood-borne prion activity in free-ranging deer from multiple regions where CWD was established.
However, the percentages should not be interpreted as estimates of CWD prevalence in those states. The study involved small, selected samples rather than a representative survey of each state’s deer population.
Likewise, four negative comparison animals are too few to establish the test’s performance across a broad range of conditions.
2. Blood testing detected prion activity in three deer without detectable deposits in other tissues
This was one of the study’s most important findings.
Among the 33 deer from CWD-endemic regions, researchers identified three animals in which the blood assay detected prion seeding activity despite no detectable prion deposits in the lymphoid or brain tissues examined.
That represented three of the ten deer classified in this early-detection category.
The result suggests that blood may provide a detectable signal at a point when other sampled tissues have not yet tested positive.
Why does that matter?
CWD has a prolonged incubation period. Infected deer can appear healthy for months or years before clinical signs become apparent. A diagnostic method that detects some infections before other tissues test positive could eventually help wildlife agencies improve surveillance and understand the early stages of infection.
There is an important distinction, though: this study demonstrated earlier detection relative to the tissue tests performed, not a universally validated timeline showing exactly when every infected deer becomes detectable in blood.
3. Detection became more common as evidence of tissue involvement increased
The probability of detecting prion activity in blood increased among deer with more extensive evidence of prion involvement in other tissues.
Researchers reported the following results:
| Tissue findings | Blood assay detected prions |
|---|---|
| No detectable lymphoid or brain involvement | 3 of 10 (30%) |
| One lymphoid tissue involved | 2 of 5 (40%) |
| Multiple lymphoid tissues involved | 6 of 10 (60%) |
| Lymphoid and brain involvement | 8 of 8 (100%) |
The pattern suggests that detectable blood-borne prion activity was more common in deer with evidence of more extensive tissue involvement.
But the relationship was not perfect. Seven of the 23 deer with evidence of prion activity in tissues tested negative in the blood assay.
That matters because a test that misses some infected animals cannot reliably rule out CWD on its own.
The results also suggest that blood and tissue testing may provide different information about an animal’s infection status.
What Does This Mean for Deer Managers?
The potential value of this research is improved surveillance, not an immediate change to how landowners manage their deer populations.
Earlier detection could eventually improve surveillance
If future studies establish reliable performance under routine sampling conditions, blood-based testing could give wildlife agencies another way to investigate CWD in free-ranging and captive deer.
A less invasive sample could be particularly useful when repeated testing is needed or when collecting tissue samples is difficult.
The study also provides evidence that the technique can detect prion activity in deer carrying different variants of the prion protein gene. That is relevant because genetic differences can influence CWD susceptibility and disease progression.
However, the current findings are preliminary. Wildlife managers would need validated testing procedures, known performance characteristics, and appropriate sampling strategies before relying on blood testing for management decisions.
Blood testing would not necessarily replace tissue testing
The assay failed to detect blood-borne prion activity in some deer with positive tissue results.
That finding argues against treating a negative blood result as proof that a deer is free of CWD.
For the foreseeable future, management decisions should continue to follow the testing and surveillance guidance of the relevant state wildlife agency. The study does not justify substituting an experimental blood assay for established diagnostic procedures.
The discovery does not change the basics of CWD management
CWD remains a fatal disease with no established cure or vaccine for infected deer.
Blood-based detection may eventually help researchers and wildlife agencies understand the disease and improve surveillance, but this study did not evaluate whether using the assay reduces transmission, changes population-level infection rates, or improves the effectiveness of harvest strategies.
Those are separate questions requiring additional research.
Important Limitations
Several limitations are important when evaluating the study’s practical significance.
Small sample size. The main analysis involved 33 deer from CWD-endemic regions and only four comparison animals from the non-endemic area. The results need to be confirmed in larger samples representing more populations and conditions.
Specialized laboratory testing. LIQ RT-QuIC is an advanced prion-amplification technique. The study demonstrated its potential under research conditions, not a routine field test that hunters can administer themselves.
Samples were collected from harvested or euthanized deer. The researchers obtained blood directly from deer shortly after death. Although the results support further development of less-invasive, potentially live-animal testing, this particular field study did not demonstrate routine testing of free-ranging deer captured and released alive.
Not every infected deer tested positive in blood. Seven of 23 deer with tissue evidence of prion activity had negative blood results. Further work is needed to understand how often blood tests miss infections and how performance varies through the disease process.
Detection is not the same as demonstrating reduced transmission. The study investigated whether prion activity could be detected in blood. It did not test a management program or show that using the assay reduces CWD spread.
These limitations do not diminish the scientific value of the discovery. They help identify what researchers need to establish before the method can be applied confidently in the field.
The Bottom Line
Researchers detected CWD prion seeding activity in blood samples from healthy-appearing, free-ranging white-tailed deer, including three animals that lacked detectable prion deposits in the lymphoid and brain tissues examined.
That is an encouraging step toward better understanding early CWD infection and developing additional surveillance methods.
But the study also showed that blood testing missed some deer with tissue evidence of prion activity. The sample size was small, and the technique remains a specialized laboratory method requiring additional evaluation.
For deer managers, the takeaway is that blood-based CWD detection is a promising research direction, not yet a replacement for established testing and management procedures. The real value will depend on whether future research can establish reliable performance across larger populations and make the technique practical for routine use.
Original Research
Trujillo, D. J., Nalls, A. V., McNulty, E. E., Denkers, N. D., Scherner, S. K., Sandoval, A. M., et al. (2026). CWD prions are present in the blood of healthy-appearing, naturally infected free-ranging white-tailed deer. Scientific Reports, 16, Article 28061.
Read the original peer-reviewed study
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