The Emergence of Lyme Disease in Appalachia (2000-2019)

Emerging infectious diseases continue to threaten human health and healthcare resources across the world, and with the sustained emergence of some like Lyme disease, this trend is only expected to get worse. Even though some research has examined the spread of Lyme disease in different parts of the United States, focusing on its origin, spread, surveillance, and reporting, there has been minimal research on the recent spread of Lyme disease into and within Central and Southern Appalachia. This is an important gap, considering that this region is at the edge of the disease's expanding incidence and range. Considering this factor and the consequences that this disease may have on the residents of Appalachia who already face an array of underlying problems like chronic conditions, decreased access to health care, and exposure through outdoor work like resource extraction, addressing this gap will be important in understanding the current and future spatial range and impacts of the continued emergence of Lyme disease in Appalachia. This study thus sought to examine the extent of the emergence of Lyme disease in Appalachia between 2000 and 2019 using spatial scan statistic. This type of analysis uses spatiotemporal information to quantify disease emergence and diffusion using retrospective case and location data within a GIS environment; hence it helped quantify the spatial distribution and diffusion of Lyme disease into and within Appalachia and identify additional areas that can be targeted with public health prevention measures. We found five statistically significant clusters of Lyme disease across the contiguous US, indicating that the disease expanded spatially over the study period. Lyme disease has more than tripled across the US, with the number of counties with RR>1 increasing from 130 in 2000 to 453 by 2019. Lyme disease also increased more than eightfold in Appalachia, with spread southwards into and within Appalachia. The number of Appalachian counties with RR>1 increased from 16 in 2000 to 127 in 2019. These findings are important in understanding the current and future spatial range and the impacts of the continued emergence of Lyme disease in Appalachia. With this understanding, we can minimize the misdiagnosis of Lyme disease and inform public health action to reduce public vulnerability.