- Case counts (2016-2025), population estimates (2016-2023), & population projections (2024-2025): Public Health Ontario.
- Query: Case counts of reportable diseases by public health unit and year. Toronto, ON: Ontario Agency for Health Protection and Promotion; extracted on March 9, 2026.
Babesiosis
Babesiosis is caused by microscopic parasites (Babesia microti) that infect red blood cells and are spread by blacklegged ticks (Ixodes scapularis), also called a deer tick. These ticks are in our region and are also spreading to new areas of the province, sometimes travelling on birds and deer. See Public Health Ontario's Vector-Borne Disease Tool.
Ticks are most active in spring and summer but can be found at any time of the year when the temperature is above freezing (0oC). As we experience global warming, ticks are becoming a greater concern.
Infections brought on by blacklegged tick bites, including Lyme disease, anaplasmosis, babesiosis, and Powassan virus, can be serious. Not all blacklegged ticks carry the infectious agents that cause infections, and not everyone who is bitten by an infected tick will develop signs and symptoms of these diseases.
See the Ministry of Health’s Tick-Borne Diseases webpage for information about:
- What blacklegged ticks look like and where they live
- How to avoid getting a tick bite and how to remove a tick
- Tick testing
- Signs and symptoms, diagnosis, and treatment
The Public Health Agency also has information about how to remove a tick and how to prevent tick bites.
Found a tick on you?
If you find a tick on you or someone else, place it in a container and get it identified on eTick.ca. If you find a tick on your pet, call your veterinary clinic. Laboratory testing is for surveillance purposes only and is not intended to replace clinical guidance.
Visit your healthcare provider as soon as possible if you are not comfortable with removing a tick, you cannot remove the tick because it has buried itself deep into your skin, or if you have concerns after being bitten by a tick, aren’t feeling well, or have any symptoms.
Contact our Environmental Health program for more information. They can be reached at 705-474-1400 or toll-free at 1-800-563-2808, ext. 5400.
Know Your Tick.
Submit a photo of your tick and find out its species within 48 hours on eTick.ca.
Local Information
2025 Statistics
Incidence rate is the number of new cases of disease divided by the number of persons at risk for the disease during a particular time period.
Cases
0*
Incidence rate per 100,000 in 2025: 0
*Includes confirmed cases in 2025.
Incidence rate per 100,000 of Babesiosis by year
More Information about Babesiosis
- Public Health Agency of Canada: Babesiosis: symptoms and treatment
- See our Lyme Disease webpage for more information about tick prevention, management, and safety.
Report to the Health Unit within one business day by fax (705-482-0670) or phone at 705-474-1400 or toll free at 1-800-563-2808, ext. 5229 if babesiosis is suspected or confirmed as per Ontario Regulation 135/18 and amendments under the Health Protection and Promotion Act, R.S.O., c.H.7.
Should one go to childcare, school, or work if they have babesiosis?
No exclusion necessary unless too ill to participate in regular activities. Person to person transmission has not been documented.
Healthcare Provider Information
Treatment of babesiosis usually involves a combination of two prescription medications. The typical combinations are:
- atovaquone and azithromycin or
- clindamycin and quinine
Consultation with an infectious disease specialist is recommended when considering the treatment and management plan.
For additional information for the treatment of babesiosis, refer to the Public Health Agency of Canada’s webpage, Babesiosis: For health professionals.
As per the most recent Infectious Diseases Society of America (IDSA) guidelines, microscopy is the gold standard diagnostic test for babesiosis and should be requested whenever babesiosis is suspected. A single negative microscopic examination is not sufficient to rule out infection.
While microscopy is the primary test, Public Health Ontario (PHO) automatically performs PCR when microscopy is positive, discordant, or inconclusive to confirm and identify the species. PCR testing can be requested after consulting with the Parasite Operational Lead or Parasitology Microbiologist at PHO (e.g. if microscopy is negative but clinical presentation is strongly suggestive of babesiosis).
Babesia serology is not recommended for diagnosis of acute babesiosis. Serology requests require prior approval from a PHO microbiologist and is generally used only for specific cases (e.g. transfusion-transmitted, transplant-associated, or congenital infection) with negative microscopy and PCR results. Serological antibody titres may be negative early in infection or in patients with severe immunosuppression. False positive reactions may occur in patients with autoimmune disorders (e.g. rheumatoid arthritis).
Co-infection warning: Babesiosis is carried by ixodes scapularis ticks, which also carry Lyme disease, anaplasmosis, and Powassan virus. Testing for these co-infections should be considered if symptoms are present.
For additional information and instruction on specimen collection, refer to the Public Health Ontario Lab's (PHOL) test information sheet on Babesia - Microscopy and PCR and Babesia microti - serology. The Infectious Disease Protocol, Appendix 1: Babesiosis also provides additional testing and management recommendations.
- Public Health Ontario: Babesiosis
- Public Health Ontario: Arthropods (e.g., Mites, Lice, Fleas, Maggots, and Ticks) - Microscopy
- Contact the Public Health Ontario Laboratories
- Public Health Ontario: The ticks of Ontario
- Infectious Disease Protocol, Appendix 1: Babesiosis
- Public Health Agency of Canada: Babesiosis: For Health Professionals
- Canada Communicable Disease Report (CCDR): Ixodes scapularis and ixodes pacificus ticks and their associated pathogens
Contact our Communicable Disease Control (CDC) program at 705-474-1400 or toll free at 1-800-563-2808, ext. 5229, or by email to cdc@healthunit.ca for more information.
Last updated: Apr 2026, by CDC