Format

Send to

Choose Destination
PLoS One. 2017 Dec 27;12(12):e0189393. doi: 10.1371/journal.pone.0189393. eCollection 2017.

Northward range expansion of Ixodes scapularis evident over a short timescale in Ontario, Canada.

Author information

1
Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
2
Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montréal, Saint-Hyacinthe, Quebec, Canada.
3
National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada.
4
National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
5
Office of the Chief Science Officer, Public Health Agency of Canada, Ottawa, Ontario, Canada.
6
Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
7
Canadian Wildlife Health Cooperative, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.

Abstract

The invasion of the blacklegged tick, Ixodes scapularis into Ontario, Canada poses a significant risk to public health because it is a vector for numerous pathogens, including Borrelia burgdorferi sensu stricto, the causative agent of Lyme disease. Baseline field sampling in 2014 and 2015 detected I. scapularis and B. burgdorferi at sites across southern, eastern and central Ontario, including a hot spot in eastern Ontario. A "speed of spread" model for I. scapularis developed by Leighton and colleagues (2012) estimated that the tick's range was expanding northward at 46 km/year. In 2016, we revisited a subset of sites sampled in 2014 and 2015 to understand the changing nature of risk, and assess whether the rate of tick invasion is consistent with the speed of spread estimate. Ticks were collected via tick dragging at 17 out of 36 sites, 5 of which were new sites for I. scapularis. Samples were positive for B. burgdorferi at 8 sites. No other I. scapularis-borne pathogens were detected. Centrographic statistics revealed an increase in the dispersion of I. scapularis positive sites in eastern Ontario. Field data for each site were then compared to the model's predicted year of establishment for each census subdivision. Our findings illustrate that the range expansion of I. scapularis and the emergence of B. burgdorferi is ongoing, and provide short timescale evidence of the processes associated with I. scapularis spread. The range front appears to be moving at a rate of ~46 km/year, with colonization of the tick behind this range front occurring at a slower and heterogeneous rate. Assessment of site-level ecological factors did not provide any insight into the underlying processes that may be influencing the colonization of I. scapularis in specific areas. Ongoing field sampling is needed to monitor this dynamic process. This study highlights the current geographic risk associated with Lyme disease, which can be used to target public health interventions to the areas of greatest risk.

PMID:
29281675
PMCID:
PMC5744917
DOI:
10.1371/journal.pone.0189393
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center