Risk factors for Lyme disease among residents of rural, suburban, and urban areas in the United States: a case-control study.

Lyme disease (LD) is the most common vector-borne disease in the United States, with 476 000 cases estimated each year. It is unclear how LD risk factors vary by residential setting. We conducted a case-control study on LD risk according to rural, urban, and suburban residential settings. Individuals from 15 high-incidence states and the District of Columbia in the Optum Research Database were identified as cases (LD medical claim) or controls (no LD medical claim, matched by county of residence and census block group population density). Participants were surveyed about LD history, outdoor activities, and residential characteristics. The final analytic data set had 750 LD cases and 965 controls. Residence in a rural setting had increased LD risk (odds ratio [OR], 1.41; 95% CI, 1.16-1.72). In multivariable analyses, activities associated with LD were hiking/walking/running or having an occupation in forests, wooded areas, or areas of tall grass (all respondents), and spending time in a yard (rural and urban residents only). Public health interventions can help prevent LD in high-incidence jurisdictions by reinforcing the near-universal LD risk for rural residents and highlighting activities that lead to increased LD risk for those in areas with less ubiquitous tick exposure like in urban and suburban settings.