Geographic Distribution and Expansion of Human Lyme Disease, United States

Emerg Infect Dis. 2015 Aug;21(8):1455-7. doi: 10.3201/eid2108.141878.


Lyme disease occurs in specific geographic regions of the United States. We present a method for defining high-risk counties based on observed versus expected number of reported human Lyme disease cases. Applying this method to successive periods shows substantial geographic expansion of counties at high risk for Lyme disease.

Keywords: Borrelia burgdorferi; Lyme disease; United States; bacteria; epidemiology; surveillance; tickborne; vector-borne infections; zoonoses.

MeSH terms

  • Animals
  • Disease Vectors*
  • Geographic Mapping*
  • Humans
  • Lyme Disease / epidemiology*
  • Lyme Disease / transmission
  • Ticks
  • United States / epidemiology