Public Health Ontario Launches New Ontario Vector-Borne Disease Tool

Public Health Ontario’s (PHO) new Ontario Vector-Borne Disease Tool offers comprehensive surveillance data on vector-borne diseases (VBDs) in Ontario, presenting data from multiple surveillance systems and partners. The VBD Tool consolidates data from several existing PHO resources into a single platform, offering a modern, intuitive experience with enhanced geographic functionality and interactive data visualizations.

Key features and uses of the tool:

• Monitor trends: Track weekly and year-to-date case counts for all reportable vector-borne diseases, including West Nile virus illness, Lyme disease, anaplasmosis, babesiosis, Powassan virus infection, at both the provincial and public health unit levels.
• Geographic analysis: Visualize mosquito and tick surveillance data, including species distribution and positive test results, using interactive maps with customizable layers.
• Risk assessment: Access interactive blacklegged tick established risk area maps, to better support public health professionals and clinicians in their management and case investigations of tick-borne diseases.
• More frequent updates: Data are available from 2014 to present. Weekly updates from May through October for human case and mosquito data, will support enhanced surveillance during peak vector activity.

What’s included in the tool:

As a centralized resource of VBD surveillance data, the following PHO resources have been discontinued, with information integrated into the new Ontario Vector-Borne Disease Tool:

• West Nile Virus Surveillance Tool
• Ontario Blacklegged Tick Established Risk Areas maps

Ontario Blacklegged Tick Established Risk Areas

In 2025, most of the risk areas are in southern Ontario along the north shores of Lake Erie, Lake Ontario and the St. Lawrence River. There are also risk areas within the health unit boundaries of Northwestern and Thunder Bay. The current map has thirteen newly identified areas in six different PHUs: MSL (2), NIA (1), PEL (2), REN (3), SEH (3), and WAT (2).

It is important to note that while low, there is a possibility of encountering blacklegged ticks almost anywhere in the province, provided the habitat is suitable (e.g., wooded or brushy areas).

Where does data from the tool come from?

The data presented in the tool are sourced from multiple surveillance systems and partners:

• Human vector-borne disease data: All VBD surveillance data are sourced from PHO’s Infectious Disease Trends in Ontario (IDTO) tool up to and including 2023. Data for 2024 and recent years are sourced from the integrated public health information system (iPHIS).
• Tick data:
  • Blacklegged Tick established risk areas: Tick dragging data (active tick surveillance) are reported to PHO on an annual basis by the National Microbiology Laboratory (NML) at the Public Health Agency of Canada.
  • Percent positive: percent of blacklegged ticks collected through active surveillance (tick dragging) that tested positive for disease using PCR/RT-PCR testing, and results are reported to PHO.
• Mosquito surveillance and testing: Maintained by PHO, includes mosquito identification and arbovirus testing for Eastern equine encephalitis virus and West Nile virus.

What can I do if I can’t find the information that I am looking for?

If you can’t find the information you are looking for, please email your questions to communicable.diseasecontrol@oahpp.ca.

We will also be offering an online demo of the tool. Check out our Events page for more details.