Tick-borne Disease Information for Health Care Professionals
Northwestern Ontario has areas where the climate and environment allow black-legged ticks to live and transmit tick-borne pathogens.
On July 1, 2023, Anaplasmosis, Babesiosis, and Powassan virus became Diseases of Public Health Significance (DoPHS). Lyme disease has been a DoPHS since 1988. We monitor the prevalence of tick-borne diseases to better understand the burden of illness as tick populations and their reservoir hosts migrate throughout the province and region.
Lyme disease
Lyme disease is an infection caused by the bacteria Borrelia burgdorferi. Being bitten by an infected black-legged (deer) tick is the most common way that humans get infected with Lyme disease.
Our infectious disease surveillance in 2022 showed that there were seven (7) cases of Lyme disease reported in the NWHU area, with an incidence rate of 8.6 per 100,000. Due to relatively small numbers, incidence fluctuates from year to year in the area, but there has been a general increasing trend in recent years. NWHU rates are similar to provincial rates and trends on average. Note that not all cases of Lyme disease are captured in this data; the early detection of ticks, prompt treatment, and testing only when clinically indicated would not necessarily result in laboratory confirmation of the disease.
Estimated risk area of Lyme disease
To learn more about risk areas for Lyme disease, please refer to Ontario Lyme Disease Estimated Risk Areas Map 2023.
We did not complete active tick surveillance in 2020-2022 but it has resumed in 2023. Tick dragging surveillance statistics for our area from 2019 showed that more than 20% of ticks were positive for Borrelia burgdorferi (the bacteria that causes Lyme disease).
Disease-carrying black-legged ticks are endemic in parts of our region and are not likely to decrease. Please consider that the data is more robust in areas where human populations and suitable habitat for black-legged ticks overlap. You may encounter an infected black-legged tick anywhere in Ontario, including our region, if the habitat allows for ticks to live.
Symptoms, testing, diagnosis, and treatment
- Public Health Ontario laboratory testing recommendations, updated April 1, 2023, indicate a modified two-tiered testing (MTTT) algorithm to maximize sensitivity and specificity, which has changes reflected in Box 6. Laboratory Testing, and Box 7: Sensitivity of Serological (Modified Two-Tier) Testing in Patients with Lyme Disease.
Lyme disease post-exposure prophylaxis criteria are the same as before:
- Black-legged tick attached for more than 24 hours AND
- Tick acquired in a risk area with more than 20% infected ticks (this includes the risk areas of NWHU) AND
- It has been less than 72 hours since the tick was removed AND
- There are no contraindications for doxycycline
Reporting Lyme disease
Lyme disease is a reportable disease under the Health Protection and Promotion Act. Reporting allows for routine, ongoing surveillance, and the identification of endemic areas.
To report Lyme disease, visit our Reporting Diseases of Public Health Significance page.
We expect additional tick-borne diseases (i.e., Anaplasmosis and Babesiosis) will be added to the reportable disease list and will inform our health care partners when changes occur.
Other tick-borne diseases – Anaplasmosis, Babesiosis, Powassan virus
Anaplasmosis in an infection caused by the bacteria, Anaplasma phagocytophilum. Black-legged (deer) ticks are the primary vector, and human infection is caused when an infected tick bites a person.
The fall of 2017 was the first year that a small number of ticks in the Kenora area tested positive for the bacteria that causes Anaplasmosis, as part of our active tick surveillance activities (tick dragging). It is uncertain whether ticks will continue to test positive. We are continuing active tick surveillance to determine if this is an ongoing risk for the area.
We previously have had sporadic black-legged ticks test positive for the parasite that causes Babesiosis and the virus that causes Powassan virus infection. This data suggests that our endemic black-legged tick populations do not routinely transmit these illnesses,
As of July 1, 2023, Anaplasmosis, Babesiosis, and Powassan virus are reportable diseases under the Health Protection and Promotion Act. Reporting allows for routine, ongoing surveillance, and the identification of endemic areas.
To report these diseases, visit our Reporting Diseases of Public Health Significance page.