Many cases of Lyme disease are under-recognized because early symptoms – typically fever, fatigue and achiness, are common in many other illnesses. At the same time, testing is fraught with pitfalls, including poor sensitivity early in the course of disease and complicated algorithms that often are misinterpreted. While historically considered a low-incidence state, North Carolina has reported an increasing number of cases over the past decade, particularly in the Blue Ridge Mountains region, where some northwestern counties are experiencing rates similar to New England states.
A new study from Ross Boyce, MD, MSc, assistant professor in the UNC Division of Infectious Diseases, with first author Gayoung Lee, MPH, a recent graduate of the Applied Epidemiology MPH program at the Gillings School of Global Public Health and partners at the N.C. Division of Public Health, looked at how introduction of a new testing approach – known as the modified two-tier testing (MTTT) – along with updated case definitions, impacted surveillance and reporting of Lyme disease in North Carolina between 2017 and 2023. The findings show that a greater proportion of cases were classified as confirmed, rather than probable, following these changes, published in Clinical Infectious Diseases.

“There’s a lot more confirmed (as opposed to probable) cases, which means we feel more certain about the diagnosis, which could ultimately shift us into the CDC’s ‘high incidence’ category in the coming years,” said Boyce.
Diagnostics have traditionally relied on a series of two blood tests performed sequentially, starting with an enzyme immunosorbent assay (EIA) that looks for antibodies to the bacteria that cause Lyme disease. The Western blot is the second test, which is labor intensive and uses electricity to split certain proteins in the blood into patterns that are compared to the pattern in people known to have Lyme disease. But these are not always dependable, particularly in early disease, and not all labs have the same standards.
Read more on the Institute for Global Health and Infectious Diseases.