Changes in the Regional Incidence of Lyme Disease Across the United States From 2004 to 2019: A PHIS Database Study

Lyme disease is the most common vector-borne disease in United States children. It was traditionally thought to be limited to the Northeast and upper Midwest due to the prevalence of tick and deer vectors in these regions. We hypothesize that as Lyme disease cases in children continue to increase throughout the country, nontraditional regions such as the Midwest and South may have an increased rate of Lyme disease compared with the Northeast region.

The Pediatric Health Information System (PHIS) database was queried for patients 19.0 years or younger who were treated for Lyme disease between 2004 and 2019 through Emergency Department and in-patient records using ICD coding. Data from 49 pediatric hospitals was included and the centers were split into 4 regions based on geographic location. The data was separated into 2 time periods: 2004 to 2014 and 2015 to 2019. Slopes were compared using a general linear model with interaction to determine if annual rates of Lyme disease were statistically different between the 2 time periods. The data was then split by geographic region and again the annual rate of Lyme disease was compared between the 4 regions. A P -value <0.008 was considered significant to adjust for multiple comparisons.

Between 2004 and 2019, 7,572 cases of Lyme disease were reported with a mean age of 9.5 years (range: 0.08 to 19.00 y) and 58% male. From 2004 to 2019, there was an annual increase of 46.5 cases. When separated by region from 2004 to 2019, the Midwest had a higher increased annual rate of Lyme disease (30.7 additional cases/year) compared with the Northeast (10.0 additional cases/y), the South (3.6 additional cases/y), and the West (2.2 additional cases/y).

Lyme disease continues to show an increased rate across the United States. The annual increase in cases in the Midwest was significantly higher than the other regions from 2004 to 2019. There does appear to be a significant regional spread, particularly in the Midwest. Awareness of the increased rate and spread of Lyme disease across the US is crucial in helping to identify national and regional strategies to diagnose and treat this disease in children.

Level IV.