Insights from the Geographic Spread of the Lyme Disease Epidemic

Taylor Eddens, Ph.D Daniel J Kaplan, M.D Alyce J M Anderson, Ph.D Andrew J Nowalk, M.D.,Ph.D Brian T Campfield, M.D
Clinical Infectious Diseases, ciy510,
Published: 16 June 2018

Reproduced by permission of Oxford University Press on behalf of the Infectious Diseases Society of America. 9c) The Author(s) 2018. All rights reserved. For permissions, e-mail: Please visit:

Lyme disease is the most common reportable zoonotic infection in the United States. Recent data suggests spread of the Ixodes tick vector and increasing incidence of Lyme disease in several states, including Pennsylvania. We sought to determine the clinical presentation and healthcare utilization patterns for pediatric Lyme disease in western Pennsylvania.

The electronic medical records of all patients with an ICD9 diagnosis of Lyme disease between 2003-2013 at Children’s Hospital of Pittsburgh were individually reviewed for cases meeting the 2011 CDC case definition for Lyme disease. 773 patients meeting these criteria were retrospectively analyzed for patient demographics, disease manifestations, and healthcare utilization.

An exponential increase in Lyme disease occurred in the pediatric population of western Pennsylvania. There was a southwestward migration of Lyme cases, with a shift in concentration from rural to non-rural zip codes. Healthcare provider involvement also changed from subspecialists to primary care pediatricians(PCP) and emergency departments(ED). Patients from non-rural zip codes more commonly presented to the ED, while patients from rural zip codes utilized PCPs and EDs similarly.

The current study details the conversion of western Pennsylvania from a Lyme-naïve to a Lyme-epidemic area, highlighting changes in clinical presentation and healthcare utilization as the epidemic evolved. Presenting symptoms and provider-type differed between those from rural and non-rural zip codes. By understanding the temporospatial epidemiology, disease presentation and healthcare utilization of Lyme, the current study may inform future public health initiatives regionally while serving as an archetype for other areas at-risk for Lyme epidemics.