Summer is the season of the ticks, and with them comes the risk of illnesses such as Lyme disease. But there is another tick-borne disease on the rise, especially in parts of Canada, that is best avoided — anaplasmosis.
Anaplasmosis is a bacterial infection that some blacklegged ticks can transmit through their saliva, according to Public Health Ontario. The illness can cause a variety of symptoms and complications, including rare complications like myocarditis — inflammation of the heart muscle.
According to the Cleveland Clinic, about 5,000 to 6,000 people contract anaplasmosis in the U.S. each year. In Canada, the disease has been relatively rare until recently, according to a 2025 Canadian Family Physician study. The data show that there are about 500 cases in Canada each year, and this may be due to blacklegged ticks moving northward into Canada because of rising temperatures due to climate change.
While anaplasmosis is a lesser-known tick-borne illness, officials urge monitoring and public awareness to help keep people healthy.
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How Is Anaplasmosis Spread and What are the Symptoms?
Tick bites can transmit anaplasmosis. When a blacklegged tick, also known as a deer tick, bites a host, it can transfer the bacteria Anaplasma phagocytophilum into the bloodstream, according to the Cleveland Clinic.
According to the Public Health Agency of Canada, a tick needs to be embedded in a host for 24 to 48 hours before the bacteria can spread. However, the transmission can happen more quickly than that. Because of this, the Public Health Agency urges anyone who finds a tick on them to remove it as promptly as possible.
If transmission occurs, an infected host may begin to see symptoms between 5 and 21 days after the bite. Common symptoms include:
- Nausea
- Chills
- Fever
- Diarrhea
- Vomiting
- Headache
- Myalgia (muscle pain)
- Abdominal pain
- Loss of appetite
Public Health Agency notes that many of these symptoms are also common indicators of Lyme disease and Powassan virus, so it’s important to be examined for any possible tick-borne illness.
If left untreated, further and more severe, but rare, complications can occur, such as:
- Organ failure
- Coma
- Seizures
- Heart complications such as cardiac tamponade, pericardial effusion, and heart failure
- Neurological complications like stiff neck, clonus, and other mental health shifts
According to the Cleveland Clinic, in more severe cases, anaplasmosis may weaken the immune system and could lead to respiratory failure, renal failure, internal bleeding, acute respiratory distress syndrome (ARDS), and in very rare cases, meningitis.
Rashes are not a very common symptom (like they are for Lyme disease), according to the Public Health Agency of Canada.
Who Is at the Greatest Risk of Developing Anaplasmosis, and What Are the Treatments?
Anyone is capable of contracting anaplasmosis, according to the Cleveland Clinic, but those who are over 50, immunocompromised, and don’t seek treatment right away are more susceptible to the disease.
If symptoms do begin to appear, the best thing to do is to seek treatment right away. Doctors usually diagnose anaplasmosis with a blood test. A medical professional may also diagnose anaplasmosis based on symptoms and a physical exam.
Once anaplasmosis is diagnosed, a doctor will usually treat it with doxycycline, a common antibiotic. The treatment will last around 10 days.
How to Avoid Anaplasmosis
To avoid tick bites, the Cleveland Clinic recommends using a bug repellent when outdoors in tall grass or wooded areas. Check for ticks after being outside, especially in warm areas like the armpits and groin.
Pets can also contract anaplasmosis, according to the Cornell Richard P. Riney Canine Health Center. Checking pets for ticks can help prevent ticks from crawling onto their owners.
This article is not offering medical advice and should be used for informational purposes only.
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Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Canadian Family Physician: Anaplasmosis
- This article references information from Public Health Ontario: Anaplasmosis
- This article references information from Cleveland Clinic: Anaplasmosis
- This article references information from the Public Health Agency of Canada: Anaplasmosis: For health professionals
- This article references information from the Cornell Richard P. Riney Canine Health Center: Anaplasmosis
