Risk Analysis from the Burden of Lyme Disease (BOLD) Study

Lyme borreliosis (LB) is endemic in many European countries. The prospective, epidemiological Burden of Lyme Disease (BOLD) study used unified case definitions to characterise LB burden in Europe. A retrospective case-control study was nested within the BOLD study to better understand LB risk factors. LB patients were evaluated at 14 healthcare practices in high-LB-incidence areas in six European countries: the Czech Republic, Germany, Poland, Slovakia, Slovenia, and Sweden between April 2021 and December 2022. Enrolled cases and age-group-matched controls were interviewed about potential risk factors, and multivariate regression analysis was used to analyse the responses. Patients with LB were more likely than matched controls to live in neighbourhoods with >50% woods, to have a garden that is composed of less than half dense trees, and to have a garden visited by wild animals. Characteristics associated with lower LB risk included being male and not having a bird feeder. The results are suggestive of risk associated with edge-of-the-forest areas, aligning with the previous literature on the increased risk of LB with forest fragmentation. Our findings support the importance of landscape structure and human-environment interactions in shaping LB risk.