Lyme Disease Emergence After Invasion of the Blacklegged Tick

Ixodes scapularis, Ontario, Canada, 2010-2016

Manisha A. Kulkarni; Isha Narula; Andreea M. Slatculescu; Curtis Russell


Emerging Infectious Diseases. 2019;25(2):328-332. 

In This Article

Abstract and Introduction


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.


Lyme disease (LD) is the most reported vectorborne disease in North America, where it is caused by Borrelia burgdorferi sensu stricto and principally transmitted by the blacklegged tick (Ixodes scapularis).[1] With northward expansion of I. scapularis tick populations from endemic areas in the United States, LD is rapidly emerging in parts of central and eastern Canada.[2–4] Although several studies have mapped blacklegged tick populations across Canada and developed models to predict future spread of ticks and LD risk,[2,3] little is known about the extent of human LD in relation to tick vector distributions at a fine geographic scale. We examined spatiotemporal trends in the occurrence and expansion of I. scapularis ticks, B. burgdorferi–infected ticks, and human LD cases over a 7-year period to elucidate the process of LD emergence in eastern Ontario, Canada.