The rising tide of tick-borne diseases, particularly anaplasmosis, is a growing concern for healthcare professionals and the public alike. This bacterial illness, transmitted by blacklegged ticks, has seen a dramatic expansion in its range across Canada, with a notable surge in cases since 2024. The story of Martin Haché, a retired accountant from the Ottawa Valley, serves as a stark reminder of the potential severity of anaplasmosis. Despite never having spotted a tick on his property, Mr. Haché suddenly fell ill and collapsed, eventually being diagnosed with anaplasmosis. This case report, published in the Canadian Medical Association Journal (CMAJ), highlights the importance of healthcare practitioners being vigilant for this fast-growing public health threat.
Anaplasmosis, while still far outstripped by Lyme disease in terms of cases, has seen a rapid rise in recent years. In Ontario, the number of anaplasmosis cases doubled from the previous year, with 315 cases reported in 2024. Nova Scotia, known for its high rates of Lyme disease, saw at least 681 cases of anaplasmosis in 2025, with 232 cases reported this year. The symptoms of anaplasmosis are often non-specific, including fever, fatigue, chills, headache, or nausea, making it difficult to diagnose without proper testing. If left untreated, the illness can turn severe, especially among the elderly or immunocompromised, leading to complications such as respiratory failure, bleeding problems, organ failure, and myocarditis.
The shift in anaplasmosis cases, particularly in dogs, has raised concerns among veterinarians. In the Kingston area, the percentage of dogs testing positive for antibodies against anaplasmosis increased from less than one percent in 2019 to 24 percent last year. This trend is mirrored in the tick populations, with a higher percentage of ticks testing positive for anaplasmosis since 2022. The Southeast Public Health unit in Ontario now has the highest infection rates for both Lyme disease and anaplasmosis, with 51 cases of anaplasmosis reported so far this year.
The question remains: will anaplasmosis follow a similar growth trajectory to Lyme disease? One silver lining is that antibiotics are very effective against anaplasmosis, and the precautions taken to prevent Lyme disease will also work for anaplasmosis. However, the increasing prevalence of ticks and the pathogens they carry poses a significant public health concern. As summer approaches and more people spend time outdoors, it is crucial to raise awareness about the risks of tick-borne diseases and take preventive measures to protect ourselves and our pets.
In my opinion, the rise of anaplasmosis is a wake-up call for society to take the threat of tick-borne diseases more seriously. While the symptoms may be mild or even asymptomatic for many, the potential severity of the illness cannot be overlooked. As we adapt to a changing climate and spend more time outdoors, it is essential to be vigilant and take proactive steps to prevent tick bites. The story of Martin Haché serves as a reminder that these diseases are not just a distant threat, but a very real and growing concern for public health.
