Map of Simcoe Muskoka


Passive Tick Surveillance

Key Messages
Tick Submissions
Technical Notes

Key Messages

  • An increasing number of ticks are being submitted to the health unit each year.
  • The proportion of these ticks that are Ixodes scapularis (blacklegged ticks) and the proportion of those blacklegged ticks that are locally acquired has been growing from 2007 to 2019.
  • A growing number of the blacklegged ticks submitted to the health unit are testing positive for Borrelia burgdorferi, the bacteria which causes Lyme disease.

Tick Submissions

  • In 2019, 12 locally acquired Ixodes scapularis (blacklegged ticks) tested positive for Borellia burgdorferi.
  • From 2007 to 2019, 52% of locally acquired ticks submitted were blacklegged ticks, between 0% in 2008 to 71% in 2019. This suggests that blacklegged ticks continue to spread in our local environment.
  • From 2007 to 2019, 1,257 ticks were submitted to the Simcoe Muskoka District Health Unit for testing.
  • Half (49%) of the ticks submitted to the health unit from 2007 to 2019 were blacklegged ticks.
  • Three-quarters (76%) of the blacklegged ticks received in this period were locally acquired, meaning they resulted from outdoor activity in the Simcoe Muskoka region.


In 2019, 12 locally acquired blacklegged ticks submitted to the health unit tested positive for Borrelia burgdorferi, the pathogen which causes Lyme disease, this is an increase from 3 in 2018 and 8 in 2017. From 2014 to 2019, there were an additional 25 black legged ticks submitted to the health that tested positive for B. burgdorferi: 21 acquired in other regions in Ontario, one in the United States and three acquired in unknown locations.


Technical Notes

When people find a tick on themselves or on other people, they are asked to submit the tick to the health unit for testing through Public Health Ontario. This is referred to as passive tick surveillance, and has been ongoing at Simcoe Muskoka District Health Unit since 2007.

The passive tick surveillance program provides us with information on the type of ticks present throughout Simcoe Muskoka communities and informs active surveillance (tick dragging) activities. The purpose is to detect and monitor the presence of blacklegged ticks (Ixodes scapularis) that can or are carrying Borrelia burgdorferi, the bacteria that causes Lyme disease in humans.

An endemic area is defined as an area in which a reproducing population of Ixodes scapularis or Ixodes pacificus tick vectors is known to occur, which has been demonstrated by molecular methods to support transmission of B. burgdorferi at that site (source: Public Health Ontario Lyme Disease Case Definition).

A risk area is defined as a location where at least one blacklegged tick was found during three person-hours of drag sampling at a location, between May and October. To warrant tick drag sampling, information from passive tick surveillance and suitable conditions to support populations of blacklegged ticks must be present.

Further Reading

For more information about ticks and Lyme Disease:

Page Last Modified: August 18, 2020.