Assessing the spread of and risk classification approaches for the blacklegged tick, Ixodes scapularis, in Ontario, Canada

Abstract

The rapid range expansion of the blacklegged tick, Ixodes scapularis, has been occurring in central and eastern Canada. This tick is a concern for human and animal health, given it is a vector for several pathogens, including Borrelia burgdorferi, the causative agent of Lyme disease. In this thesis, spatial and temporal patterns of I. scapularis and its pathogens were examined in Ontario, and surveillance approaches utilized to classify Lyme disease risk across Canada were assessed. Drag sampling at 48 sites in Ontario from 2017 to 2019 detected I. scapularis at 30 sites and B. burgdorferi at 9 sites. Tick and pathogen hotspots were identified in eastern Ontario in 2017 and 2018, respectively. A one year gap between I. scapularis presence and B. burgdorferi detection was detected at 4 of 15 sites. There was limited agreement among the seven Lyme disease risk classification approaches assessed. Understanding the expansion of I. scapularis and B. burgdorferi can help target future risk areas where primary methods of prevention should be implemented to minimize the transmission of tick-borne pathogens.