Over a recent 10-year period, western Pennsylvania transformed from a Lyme-naive to a Lyme-endemic area as cases of the tick-borne disease increased exponentially, researchers reported in Clinical Infectious Diseases.
“As pediatric infectious disease physicians, we were anecdotally seeing patients with Lyme disease with increasing frequency at our hospital and that was new,” Brian Campfield, MD, pediatric infectious disease specialist at the University of Pittsburgh School of Medicine, told Infectious Disease News. “Previously the cases of Lyme disease that we would see were often in children who we thought had acquired it somewhere else and traveled to our area.”
Campfield and colleagues reviewed all diagnosed cases of Lyme disease recorded at the Children’s Hospital of Pittsburgh between 2003 and 2013 to see how many met the 2011 CDC case definition. They included 773 patients in the final retrospective analysis and studied patient demographics, disease manifestations and health care utilization.
According to the study, the pediatric population of western Pennsylvania experienced an exponential increase in Lyme disease burden during the study period from five documented cases between 2003 and 2005 to close to 300 cases in 2013, with a calculated doubling time of around 1.6 years. Campfield and colleagues noted a shift in the concentration of Lyme disease cases from rural zip codes to nonrural zip codes. A southwestward migration of cases also was observed, with the most common site shifting from Butler County — north of Pittsburgh — from 2008 to 2010 to Allegheny County and Pittsburgh from 2011 to 2013.
Amid an increase in cases, the type of provider diagnosing Lyme disease changed. Diagnoses were comparably made at pediatric subspecialty clinics, primary care pediatricians and EDs until 2008. From 2008 to 2012, however, diagnoses at primary care providers and in EDs increased equally over time, whereas the frequency remained unchanged at subspecialty providers. Patients with nonrural zip codes were more commonly diagnosed in EDs, whereas patients with rural zip codes were similarly diagnosed at both primary care providers and EDs.
According to Campfield and colleagues, western Pennsylvania’s shift from a Lyme-naive to Lyme-endemic region highlighted changes in clinical presentation and health care utilization. They suggested the study could inform local public health initiatives other areas that may soon face a high burden of Lyme disease.
“A majority of the patients actually came from the city of Pittsburgh or the suburban towns, as opposed to the rural areas,” Campfield said. “Often, the thought is you have to be out in the woods to get Lyme disease, but this would suggest that, no, you simply need to be someplace that has the tick and that could be anywhere as rural as your city park.” – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.