Background: Tick-borne diseases are increasing in incidence in the United States, however limited data exist on regional trends of associated hospitalizations. Using a nationally distributed dataset of U.S. hospital-based medical records, we aimed to assess trends in incidence of hospitalizations from tick-borne disease by geographic region.
Methods: Data were examined from 156 U.S. hospitals from 2009-2014 to identify hospitalizations with tick-borne disease. Cases were described and Poisson regression used to estimate the annual percent change (APC) and associated 95% confidence intervals (CI) in incidence by region over time.
Results: Overall, 2,543 hospitalized patients with tick-borne disease were identified (average annual incidence=28.4 cases/100,000 hospitalized persons), including 1,613 (63%) with Lyme disease, 379 (15%) tick-borne fever, 293 (12%) ehrlichiosis, 93 (4%) babesiosis, 43 (2%) rickettsiosis, and 122 (4%) multiple tick-related diagnoses. Tick-borne diseases varied significantly by region, with Lyme disease more frequent in those residing in the Northeast (68%) than the South (57%) or West (42%) and tick-borne fever more common in the West (28%) versus the South (18%), Midwest (14%) and Northeast (13%) (p<0.0001). Significant increases in tick-borne disease hospitalizations were identified across nearly all U.S. regions, ranging from 15% per year in the South (95% CI=8-24%) to 45% per year in the West (34-58%), with the exception of the Northeast, where incidence declined by 6% per year (0.04-11%). Lyme disease hospitalizations showed similar trends, with the greatest increase in the South (APC=53%, 95% CI=33-76%) and a decrease in the Northeast (APC= 13%; 3%-23%). Hospitalizations with tick-borne fever increased in the Midwest (APC=49%; 8-206%) and Northeast (APC=18%; 4-34%); with ehrlichiosis increased in the West (APC=231%; 75-306%); and with babesiosis increased in the South (APC=50%; 12-201%) and the Midwest (APC=21%; 5-39%).
Conclusion: Incidence of hospitalizations from tick-borne disease is increasing throughout much of the nation, except in the Northeast where decreases in Lyme disease were observed. While hospitalizations with tick-borne diseases remain rare, the increases noted are substantial and may reflect rising incidence of these diseases within the represented states.
E. Ricotta, None
D. R. Prevots, None