A prospective active surveillance study across six European countries found medically attended Lyme borreliosis incidence of about 660 per 100,000 population in high-endemic areas—far above official surveillance figures. The research points to under-detection or under-reporting in surveillance systems that rely on routine notification pathways. By combining active surveillance with clinical verification, the study provides a clearer view of real-world burden, including where disease is most frequently seen. That gap can directly influence health planning for diagnostic capacity, clinician awareness, and patient access to timely treatment. For public health decision-makers and healthcare systems, the findings suggest that surveillance-driven estimates may underestimate exposure and clinical workload in high-incidence regions. The study also sets a higher benchmark for evaluating improvements in tick-borne disease control measures and public education initiatives.