Analysis of surveillance data for 2010-2016 in eastern Ontario, Canada, demonstrates the rapid northward spread of Ixodes scapularis ticks and Borrelia burgdorferi, followed by increasing human Lyme disease incidence. Most spread occurred during 2011-2013. Continued monitoring is essential to identify emerging risk areas in this region.
Keywords: Borrelia burgdorferi; Canada; Ixodes scapularis; Lyme disease; bacteria; blacklegged tick; epidemiology; tickborne diseases; vector-borne disease.