Larry M. Baddour, MD reviewing Lantos PM et al. Open Forum Infect Dis 2015 Sep 27.

The progressive increase of Lyme disease cases, particularly in southwestern Virginia, over a 15-year period is striking and suggests southward expansion of the disease.

Lyme disease (LD) has been endemic to limited areas of the U.S., including the northeast coastal states and the upper Midwest. In response to an increasing number of cases reported in Virginia, including from the southern border of Virginia (which is shared by North Carolina) — i.e., outside of previously identified endemic areas — researchers conducted a detailed evaluation, including spatial and spatiotemporal cluster analyses. Investigators included both probable and confirmed cases, based on CDC surveillance definitions, reported to the respective state health departments between 2000 and 2014. In addition, they included residential zip codes for each case and used a geographic information system to geographically show pertinent data.

More than 11,000 LD cases were included for subsequent analysis, 89% and 11% of which were registered by the Virginia and North Carolina health departments, respectively. A trend toward an increase in the number of cases was apparent only for Virginia; the most marked annual increase was in southwestern Virginia. New disease clusters were identified along the Appalachian chain between Charlottesville and the North Carolina border and along the southeastern border of older clusters in northern Virginia.

Citation(s):

Lantos PM et al. Geographic expansion of Lyme disease in the southeastern United States, 2000–2014. Open Forum Infect Dis 2015 Sep 27; [e-pub].

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