Lyme Disease Risk May Be Underestimated in North Carolina
What if Lyme disease risk exists in areas not officially labeled as endemic? Evidence from North Carolina suggests that infected ticks may be present even when public health maps say otherwise.
This raises an important question: do current Lyme disease maps fully reflect real-world exposure risk? Findings from the Outer Banks suggest a gap between surveillance data and environmental risk.
The Centers for Disease Control and Prevention (CDC) reports that black-legged ticks (Ixodes scapularis) are now documented in nearly half of U.S. counties.
“The presence of I. scapularis has been documented in 1,420 counties,” according to Eisen from the CDC. However, designation as an endemic area requires reported human cases, not just the presence of infected ticks.
Infected Ticks in the Outer Banks
A study published in Zoonoses and Public Health identified Borrelia burgdorferi-infected ticks in 50% of surveyed sites in the Outer Banks of North Carolina.
“The spirochetes were consistently detected in questing adult ticks over an 18-year period,” reports Levine from North Carolina State University.
The strains identified showed 98–99% homology with Borrelia burgdorferi sensu stricto, similar to strains found in the northeastern United States.
Why Some Areas Are Not Labeled Endemic
Despite evidence of infected ticks, the Outer Banks has not been designated as endemic for Lyme disease.
CDC criteria require at least two confirmed human cases within a county. In some regions, infected ticks may be present even when human cases are underreported or not recognized.
This creates a gap between environmental risk and official classification.
Implications for Clinicians and Patients
These findings suggest that Lyme disease risk may extend beyond traditionally recognized endemic regions.
Patients and clinicians may consider exposure risk based on environment and travel history, not solely on official maps.
Tick-borne infections may occur in areas where surveillance data are limited or evolving.
Clinical Perspective
Lyme disease risk is influenced by both tick presence and reporting patterns. Areas not labeled as endemic may still pose a risk of exposure.
Patients may benefit from awareness of tick bite prevention, review of Lyme disease symptoms, and understanding testing limitations when evaluating possible infection.
Learn more in the Lyme disease prevention hub and testing and diagnosis hub.
References
- Levine JF et al. Borrelia burgdorferi transmission in the Outer Banks. Zoonoses Public Health. 2016.
- Eisen RJ et al. Distribution of Ixodes ticks in the U.S. J Med Entomol. 2016.
- Pegram PS et al. Lyme disease in North Carolina. South Med J. 1983.
- CDC Lyme disease surveillance data.
- TickChek Lyme disease map.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
Considering how many people that have it, or know someone that has it, I can tell you that the west side of the Cascades can be added to that list. But let’s be honest…this is an epidemic situation, not endemic. The powers that be know it. I just wish I knew why they are denying it. People are suffering, and very few even care.
I have lyme. I was diagnosed late last year. I went through the standard 20 day treatment and then… wha.. la… I would be good as new. Well… I have still always felt miserable up to today. So I when to get retested and low and behold I still have lyme. So I fall right into your statement ” People are suffering, and very few even care”…. I can find no one who raises and eyebrow that I still tested positive. The only thing I was told was that “sometimes” there can be a false positive and to get check again in 6 months. So what do I do with my crappy days until my next test (which I am sure will be positive again). The rollercoaster does not stop and the end of the ride.
The tests cannot be used to tell when a tick-borne illness has resolved.
The majority of cases of Lyme disease are reported in the Northeast and north central United States ( Bacon et al., 2008 ), but confirmed cases of Lyme disease are also regularly reported in the Southeast ( Pegram et al., 1983 ; Oliver, 1996 ; Centers for Disease Control and Prevention (CDC), 2015 ). Few areas in the Southeast currently meet Centers for Disease Control and Prevention criteria, which requires two indigenous cases to be reported in the same county for the disease to be considered endemic ( CDC, 2015 ). Human cases are less numerous and more widely geographically dispersed in North Carolina and other southeastern states CDC (2015). However, infected questing
transmission. In these studies, we have focused on the primary pathogen of public health interest, but there is a great deal more that we need to learn to clearly understand the dynamics of spirochaete transmission. Although vector competent ticks and reservoir competent hosts are abundant in the state, the vectorial capacity of resident for transmission to humans needs further study. Arsnoe et al. (2015) documented differences in the questing behaviour of nymphal
I agree