October 2, 2024

By Rachel Morrow, Gillings School communications fellow

While the ticks that carry Lyme disease have historically been associated with northeastern states, recent evidence shows that these ticks are expanding their geographic range southward along the Appalachian Mountains. This geographic shift establishes the need for effective prediction and surveillance tools to understand and prevent Lyme disease in humans.

Dr. Ross Boyce

Dr. Ross Boyce

Data collected from pet dogs at routine veterinary checkups can be used to approximate the risk of Lyme disease for humans, according to a recent study in northwestern North Carolina led by Peyton Pretsch, MPH, a doctoral candidate from the UNC Gillings School of Global Public Health, and in conjunction with Ross Boyce, MD, assistant professor of medicine and epidemiology at UNC-Chapel Hill and member of the Institute for Global Health and Infectious Diseases. 

During routine heartworm screenings for dogs, which are also vulnerable to Lyme disease, veterinary clinics collect blood and test for antibodies to the bacteria that causes Lyme disease. Given that humans and pet dogs would likely have encountered many of the same environmental conditions that would expose them to a tick, this data can be used to estimate the exposure risk of Lyme disease for humans. 

Accurately predicting and preparing for Lyme disease is essential, since, in the United States, Lyme disease is the most frequently reported vector-borne disease — one passed to humans via an insect. Among tick-borne diseases, Lyme disease accounts for more than three-quarters of reported cases. 

While most infections will resolve with antibiotics, untreated cases of Lyme disease can progress to carditis — inflammation of the heart — and arthritis, among others. Even with treatment, 10-15% of people will experience post-treatment Lyme disease syndrome, characterized by chronic pain, fatigue and cognitive impairments often referred to as “brain fog.” 

This study focused specifically on Watauga County, N.C., the home of Boone, with data drawn from 2017 through 2021. The percentage of dogs exposed to Lyme disease increased from 2.2% in 2017 to 11.2% in 2021, indicating an increase of ticks carrying Lyme disease in Watauga County between those years. Additionally, geographic analysis suggests that ticks carrying Lyme disease had become more dispersed across Watauga County by 2021 as compared to a more clustered existence in 2017. Both trends are consistent with public health surveillance data and suggest an increased risk of Lyme disease for humans. 

This research is impactful in both the data collection strategies and the research outcomes. The individual-level data from veterinary clinics has two primary benefits. The individual-level factor allows for more granular analysis including evaluating specific risk areas and geographic risk factors. The availability of data from veterinary clinics allows these Gillings School researchers to leverage information that would be difficult to produce among human populations. 

“Findings from this research demonstrate that the risk for Lyme disease has increased rather quickly over the past several years in northwestern N.C.,” says Pretsch. “In the later years of the study, the percentage of dogs testing positive for antibodies against the bacteria that causes Lyme disease in Watauga County was similar to that of traditionally high-incidence states like Rhode Island, Connecticut and Maine.” 

With this increase in Lyme disease cases in N.C., using research strategies such as data from veterinary clinics can allow researchers to continue to track and prevent Lyme disease cases making, dogs no longer just man’s best friend but also man’s best research companion.

Read the full article in Emerging Infectious Diseases.


Contact the UNC Gillings School of Global Public Health communications team at sphcomm@unc.edu.

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