For clinicians

Diagnosing and treating Lyme disease can be very challenging. CanLyme supports an understanding of Lyme and other vector-borne diseases that considers emerging research, clinical expertise, patient experiences and the strengths and limitations inherent in our healthcare system.

Understanding vector-borne illnesses

Lyme disease is one of multiple interacting vector-borne infections that can be transmitted by routes beyond a tick bite. It is most commonly caused by a corkscrew shaped bacteria, Borrelia burgdorferi, which has unique properties that enable it to move out of the bloodstream into tissues, take on various morphologies, become dormant, evade the immune system and trigger various immune and inflammatory processes. Manifestations of vector-borne diseases can be found in virtually every system in the body, including the brain and nervous system, heart, skin, joints, stomach and eyes. 

Borrelia are complex organisms, and disease manifestations can also be complex and vary widely between patients. In the context of challenges related to testing and defining the disease, limited research, and systemic healthcare barriers, Lyme and associated infections can be challenging to manage. The importance of curiosity and open-mindedness is paramount when treating these emerging and complex infections. 

A doctor looks out over their desk at a patient, while a patient explains their situation.
Two researchers stand together with a clipboard looking at data.

Who is at risk?

Different strains of Borrelia and several other tick-borne pathogens can be found across Canada and worldwide. When considering risk maps for these pathogens it’s important to keep in mind the limitations of surveillance data. Data is limited by when, where and how we look for ticks and the pathogens they carry.

In Canada and worldwide there are many areas with limited or no active surveillance, and birds and animals are constantly carrying ticks into new territory. When considering a diagnosis for tick-borne illnesses, species of ticks and pathogens found in a patient’s place of residence, bordering provinces and states, and the patient’s travel history should be considered. Borrelia can remain dormant, resulting in asymptomatic infection for extended periods of time. All previous domestic and international travel history should be taken into account when considering the testing and diagnosis of vector-borne pathogens. 


Lyme disease is a clinical diagnosis made in the context of a patient’s history and symptom presentation. Testing may be helpful in confirming a diagnosis, but should never be solely relied upon to exclude tick-borne infections from the differential diagnosis. Although testing is least accurate in the first few weeks after infection, false negatives are possible at any time. Patients with a negative test can still have Lyme disease, and patients with symptoms of Lyme may have other illnesses.

Many patients who have Lyme disease do not recall seeing a tick, feeling a tick bite or having a rash. Patients with Lyme disease often experience symptoms that wax and wane, and migrate to different areas of the body. Symptoms checklists can be helpful for patients and clinicians to articulate symptoms and monitor them over time. Tools that assess pain, mental health and quality of life may also be helpful. See the Additional resources section below for links to checklists related to Lyme and other tick-borne infections.

Patients may have Lyme disease along with other tick-borne infections often referred to as co-infections, other infections including reactivated viruses, and other medical problems which may or may not be related to Lyme. Patients with Lyme disease may be diagnosed with other diseases such as Fibromyalgia, ME/CFS, MS, juvenile arthritis and other autoimmune and inflammatory diseases before receiving a diagnosis of Lyme disease. Including Lyme disease in the differential diagnosis early on is essential. Lyme disease is much more challenging to manage when diagnosis and treatment are delayed. 

Limitations with testing protocols within Canada and internationally are well documented. Many international labs have robust research and development standards; it can be challenging to stay up to date with specific research for each test from each lab. Two labs that many Canadian patients use are Armin Labs in Germany and IGeneX in the US. Test results from these labs often contain more detail than standard testing in Canada and need to be considered on an individual basis. Tests from any lab, domestic or international, also need to be interpreted in the context of a thorough patient history and examination.

Canadian and US health agencies acknowledge that the number of cases of Lyme disease is higher than case reporting. Although there are around 30,000 reported cases in the US every year, the US CDC reports that approximately 476,000 Americans are diagnosed and treated for Lyme disease every year. Although further research is needed to bring clarity to this issue, there is a growing body of evidence indicating that patients diagnosed with Lyme disease have recovered through the use of treatments beyond those outlined in the IDSA guidelines.


Historically, Canadian clinicians have been encouraged to follow treatment guidelines created by the Infectious Diseases Society of America, or IDSA. Treatment based on these guidelines often leaves patients with lingering symptoms that can be life altering. The term Post Treatment Lyme Disease Syndrome, or PTLDS, is sometimes used to describe lingering symptoms after a limited course of antibiotic treatment. The term has historically been used to imply that ongoing symptoms are not caused by persistent infection. The current testing protocol in Canada is not useful in ruling out the persistence of infection after treatment. Other terms such as chronic, persistent or long Lyme disease do not inherently associate ongoing symptoms with the effectiveness of treatment.

Persistent symptoms after treatment for Lyme and other tick-borne infections may be due to persistence of these pathogens in the body, inflammation, immune dysfunction or other mechanisms. Unfortunately standard treatments to address each of these possible causes are not always effective for patients with tick-borne infections. There is a growing body of in vitro, animal, and human research looking at the effectiveness of longer courses of antibiotics, the use of combination antibiotic treatments and the use of herbal treatments against these pathogens. Clinicians and patients must navigate the information that is currently available in the context of the risk and cost of treatment options and their potential benefit.

There are also guidelines, such as those published by ILADS, the International Lyme and Associated Diseases Society, that have been created by treating clinicians and researchers who acknowledge and work within a more complex framework for tick-borne illnesses. These guidelines encourage a more nuanced approach that includes the use of combination antibiotic therapy and other treatment modalities, and is informed by the patient’s response to treatment. 

There are currently no treatments for acute or chronic Lyme disease that work for all patients all of the time. Patients receive better care when there is collaboration, coordination and communication between the various healthcare professionals involved in their care, and when treatment response is considered in the clinical decision making process.

CanLyme cautions against the use of single dose doxycycline or other antibiotic, for treatment of tick bites, rashes or other manifestations of Lyme disease. Read more about the shortcomings of the supporting research or watch this video.

Healthcare education

Clinicians who are interested in deepening their understanding of tick-borne diseases have many options for online and in-person courses.

ILADS Vector-borne Illness Fundamentals Course is a starting point in gaining a broader understanding of vector-borne diseases. ILADS has many other online courses, international conferences and offers clinician mentorship and support.

Invisible International is a non profit organization, supporting ongoing medical education with research based courses curated by top international researchers and clinicians. They offer a variety of complementary CME courses that are focussed and concise.

CanLyme provides Education Grants to support clinicians in deepening their understanding of vector-borne illnesses.

Additional Resources

ILADS provides an explanation of the controversies and challenges surrounding tick-borne infections, diagnosis, testing, treatment and clinical management of these diseases. This resource includes an extensive reference list for further exploration on these topics.

Checklists for Lyme and other tick-borne infections include those by Dr. Burascano, Dr. Horowitz, and Dr. Fallon, et al.

Learn more about approaches to testing, diagnosis and treatment, including some of the regulatory considerations in these videos by internal medicine physician Dr. Ralph Hawkins and infectious diseases physician Dr. Jack Lambert.

Find out more about the limitations of Canadian two tiered testing in this Adverse Reaction Bulletin published by the Government of Canada.