Important Change to Passive Tick Surveillance in Ontario

Advisory Alert

September 23, 2020

*Cette information est seulement disponible en anglais.

To: Community health providers

As of September 20, 2021, the National Microbiology Laboratory (NML) will no longer test blacklegged ticks (BLT) collected through passive surveillance. Individual tick pathogen testing will no longer be available. This is a change from the previous practice, where all BLTs are submitted for testing. Public Health Ontario (PHO) will continue to accept tick submissions and provide identification results to various submitters, but this can take weeks to process. An alternative for clinicians is, an online image-based tick identification platform, which may produce faster results.

The diagnosis of Lyme disease is mainly clinical, supported by a possible history of tick exposure. It is important to remember that tick identification and pathogen testing of ticks as part of Ontario’s surveillance system were not specifically designed to aid clinicians in managing tick bites. Individual tick pathogen testing results may cause unintended harm to the patient due to:

Please note that despite these changes, monitoring of tick populations in Ontario remains an important part of public health activities. Active surveillance efforts, which involve ‘dragging’ for ticks in specific areas to determine if pathogen carrying ticks are present, will continue. Ticks found during active surveillance practices will be submitted to the NML for identification and pathogen testing.

Further information about Lyme disease can be found on PHO’s Lyme disease resource page, the Ontario Ministry of Health’s Lyme disease website, and by visiting or by calling Public Health Sudbury & Districts at 705.522.9200 (toll-free 1.866.522.9200).


Original Signed By

Dr. Penny Sutcliffe
Medical Officer of Health and Chief Executive Officer

NOTE: All Advisory Alerts are found on our website.

This item was last modified on September 24, 2021