Lyme Disease

Lyme disease is an infection caused by Borrelia burgdorferi, a bacteria transmitted through the bite of an infected blacklegged tick (Ixodes scapularis). Most humans are infected through the bite of an immature tick (nymph) during the spring, summer and fall months.

Risk of transmission of Borrelia burgdorferi from tick to human increases with the duration of tick attachment. When ticks acquired in high-risk areas have been attached less than approximately 24 hours, the probability of infection is low enough not to warrant use of prophylaxis. Nevertheless, in this situation patients should be counselled to observe for rash—especially an expanding red rash at the site of the initial tick bite—or other symptoms of Lyme disease for 32 days, and return for medical assessment should these arise. Partial or full engorgement of nymph and adult ticks would suggest the tick has been feeding longer than 24 hours, and should trigger the recommendation for prophylaxis for those eligible. The general principles of antibiotic stewardship should be applied and an informed consent discussion should include the risks of antibiotic therapy to the individual.

Blacklegged ticks in various stages of feeding:

Three nymphs of the blacklegged tick are shown in different stages of feeding.

The following image shows 5 female blacklegged ticks in different stages of feeding.

For additional photos showing blacklegged ticks in various phases of engorgement from feeding visit the Tick Encounter Resource Center website.

Blacklegged ticks are present in Ottawa and transmission of Lyme disease from infected ticks is known to occur here. Regions surrounding Ottawa, including many locations where Ottawa residents visit for recreation, may also be considered risk areas for Lyme disease. For the most current map visit the Public Health Ontario - Lyme disease webpage, under “Type of Resource” click on “Surveillance Report” and look for most current year.

Information regarding both number of cases and incidence of Lyme disease in Ottawa can be found on the 

Reportable Infectious Diseases Statistics page.

Diagnosis of early localized Lyme disease is based solely on clinical presentation and history of potential exposure. Patients may not recall a tick bite because nymphs can be the size of poppy seeds and difficult to see, so an assessment of likelihood of exposure to blacklegged ticks is an essential part of the risk assessment.

Please report all suspect and clinical diagnoses of Lyme disease to OPH, not only those confirmed by laboratory testing.

Early localized disease: (3 to 32 days following tick bite)

A classic sign is erythema migrans, a single expanding red rash with clearing behind the outer ring ("bull's eye") and usually greater than 5 cm in diameter. However, the appearance of the rash may vary (e.g., there may not be any central clearing) and it is not present in approximately 20 to 30% of cases. Other symptoms can include fatigue, fever, headache, lymphadenopathy, myalgia and arthralgia. Note: a small area of erythema at the site of the tick bite may appear within the first 48 hours of a bite but may reflect local irritation rather than early Lyme disease.

The Government of Canada website has more images of rashes post exposure.

Early disseminated disease: (days to weeks following tick bite, less than 3 months)

If untreated, the infection can spread via the bloodstream and cause additional erythema migrans rashes on other areas of the body, fatigue, weakness, neurologic symptoms (e.g., facial nerve palsy, meningitis, encephalopathy) and/or cardiac symptoms (carditis, conduction abnormalities).

Late disseminated disease: (months to years following tick bite)

If untreated, about 60% of patients may develop arthritis (chronic or intermittent, often affecting the knees) and up to 5% may have neurologic symptoms (problems with memory and concentration, paresthesias).

Post-treatment Lyme disease syndrome

Approximately 10 to 20% of patients may have lingering fatigue, pain, joint and muscle aches, sleep disturbance or cognitive difficulties following appropriate antibiotic treatment. The cause of these symptoms is not known. Treatment with extended courses of antibiotics has not proven effective for post-treatment Lyme disease syndrome and carries risk of serious complications.

In most cases, the visual identification of erythema migrans* can be sufficient to diagnose a patient with Lyme disease who has been bitten by a tick from an area known to have ticks that carry Borrelia burgdorferi. Delaying antibiotic treatment for Lyme disease while awaiting results of laboratory serology testing in these circumstances is not recommended, nor is laboratory testing of ticks as discussed below as per the National Microbiology Laboratory (NML):

• Turn-around times for tick identification and testing are too long to be useful in the patient’s management and the results of tick testing can be misleading. For example, positive results do not mean that a person has become infected because for most tick-borne pathogens, infected ticks must be attached for at least 24 hours in order for transmission to occur. Likewise, negative results do not mean there is zero risk of infection, since a person might have been bitten unknowingly by a different infected tick that was not found and hence could not be tested.
• In special circumstances, there are rare instances where results of tick testing may be informative to health care professionals (e.g., when a person is allergic to antibiotics and cannot receive a preventative treatment, or if a patient has clinical signs of a particular disease and the results of tick testing would help confirm the etiologic agent of the infection). Such special requests are handled on a case-by-case basis and health care professionals who want such testing should consult with staff from the NML to describe the circumstance before ticks are submitted (nml.fs-lnm.et@phac-aspc.gc.ca, (204) 789-7434 or (204) 789-7662). Ticks will only be accepted for testing when there is a strong justification and value to doing so. 

* In the absence of erythema migrans, clinical diagnosis may be more difficult and consideration should be given to serologic testing of the patient not only at the time of the first visit, but again at least 2 weeks later. In the first 2 weeks of infection, serologic sensitivity is low; therefore, a convalescent sample 2 to 4 weeks after the first test will improve test sensitivity. Each of these tests is conducted at the PHO laboratory as two-tier testing (as of April 1, 2023, PHOL will begin testing patient samples for Lyme disease antibodies using the Modified Two-Tier Testing (MTTT) algorithm. In this algorithm, initial screening (Tier 1) will be performed by IgG/IgM ELISA on whole cell lysates. Samples that are reactive or indeterminate will be further tested (Tier 2) on a second IgG/IgM ELISA targeting specifically VlsE1 and pepC10 antigens.).

Serologic testing is also useful for patients in whom early disseminated or late Lyme disease is suspected.

A downloadable requisition form is available from the Public Health Ontario Laboratory's website (English only).

If the tick bite occurred in Europe, please provide a specific travel history on the lab requisition form, as the specimen will be forwarded to the National Microbiology Laboratory for appropriate testing.

Private laboratory testing for Lyme disease is not recommended. These laboratories often use unvalidated tests and/or interpretation criteria – treatment decisions should not be based on these tests.

Revised Tick Surveillance Program: (As of September 20, 2021)

1. Public Health Ontario will continue to accept ticks for identification from members of the public through health care providers. Ottawa Public Health does not accept ticks for identification. The tick identification results will be reported to submitters. It may take up to three weeks to receive identification results back from PHO’s laboratory during peak season. The online platform (etick.ca) may be an alternative option if you require a faster result.
2. PHO will no longer send blacklegged ticks to the National Microbiology Laboratory (NML) for pathogen testing (except in rare instances by special request after consultation with NML staff). As a result of this change, submitters will no longer receive pathogen results from their submitted ticks.

As per Infectious Disease Society of America (IDSA) Guidelines for Lyme Disease, tick identification should not be used for diagnosis and management of Lyme Disease.

All cases of Lyme disease, whether clinically diagnosed or laboratory confirmed, are reportable to local public health under the Health Protection and Promotion Act. Note: This includes individuals who have been clinically diagnosed with Lyme disease in the absence of serology. Ottawa Public Health is mandated to collect information on clinical signs and symptoms (such as diameter of any erythema migrans), as well as information on tick exposure.

Health Care Provider Lyme Disease Reporting Form [PDF 170 KB]

Antibiotic treatment of Lyme disease:

For drugs, dosages, and duration of treatment therapy, please consult a reference such as “Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis and Treatment of Lyme Disease”, which is listed in the Physician Resources section below.

Following tick exposure, a patient with an erythema migrans rash should be treated for Lyme disease promptly, without the need for serological testing. Most cases of Lyme disease can be treated successfully with appropriate treatment. Patients who are treated with an appropriate antibiotic early in the course of illness (early disease) tend to recover more quickly than those who are treated at later stages of disease (late disease). Doxycycline, cefuroxime axetil, and amoxicillin are the most commonly recommended oral antibiotics. Doxycycline as treatment is not recommended in pregnancy.

Short-term use of doxycycline is considered acceptable in breastfeeding mothers. More information can be obtained from LactMed (English only)

Early disseminated Lyme disease with meningitis or cardiac symptoms or late disseminated Lyme disease may also be treated with oral antibiotic agents, including doxycycline. The longer duration of treatment of late disseminated disease means that children younger than 8 years should receive an antibiotic other than doxycycline. The American Academy of Pediatrics states in its 2018 Red Book that there “are limited safety data on the use of doxycycline for >21 days in children <8 years if age.” Consider consultation with an infectious disease specialist in the event of disseminated Lyme disease.

Chemoprophylaxis following a tick bite:

A single dose of oral doxycycline may be offered to adult patients (200 mg dose) and to children of any age (4.4 mg/kg, up to a maximum dose of 200 mg), when all of the following conditions are met:

• patient presents with an engorged or partially engorged blacklegged tick or history of one that was attached for more than 24 hours
• exposure in known risk area
• it has been less than 72 hours since removal of the tick
• doxycycline is not otherwise contraindicated

When a patient has been exposed to ticks in other health units:

Public Health Ontario (PHO) has a risk area map that indicates places in which chemoprophylaxis should be considered after tick bites. For the most current map visit the Public Health Ontario Lyme diseases webpage, under “Type of Resource” click on “Surveillance Report” and look for most current year.

Please visit specific health units' websites for the current recommendations for exposure to ticks in their respective health units. A listing of Ontario public health units can be found at the Ministry of Health and Long-Term Care website.

The Institut national de santé publique Québec (INSPQ) publishes a risk area map for Québec at https://www.inspq.qc.ca/zoonoses/maladie-de-lyme.

Health Canada has a risk area map for Canada at https://www.arcgis.com/apps/dashboards/447f0300dab344049ddc19a5ba53bfe9.

If a patient presents with the tick attached:

1. Use tweezers to grasp the tick where it attaches to the skin.
2. Pull the tick straight out, slowly and firmly, and do not jerk or twist the tick as this can cause the tick's mouthparts to break off. Avoid squeezing the tick's abdomen.
3. Disinfect the feeding site after the tick is removed.

4. Tick identification:

a) Revised Tick Surveillance Program: (As of September 20, 2021)

1. Public Health Ontario will continue to accept ticks for identification from members of the public through health care providers. Ottawa Public Health does not accept ticks for identification. The tick identification results will be reported to submitters. It may take up to three weeks to receive identification results back from PHO’s laboratory during peak season. The online platform (etick.ca) may be an alternative option if you require a faster result.

2. PHO will no longer send blacklegged ticks to the National Microbiology Laboratory (NML) for pathogen testing (except in rare instances by special request after consultation with NML staff). As a result of this change, submitters will no longer receive pathogen results from their submitted ticks.

• Application of a Health Canada approved insect repellent containing DEET or icaridin to exposed skin and clothing
• Wearing long pants, a long sleeved shirt, shoes and socks to cover exposed skin
• Tucking pants into socks
• Wearing light coloured clothing so it is easier to spot ticks
• If possible, staying on the trails when hiking in the woods or walking in long grass
• Performing a "full body" check (also on children, and pets if applicable) for ticks. Ticks often attach in areas such as between toes, behind knees, in the groin, armpits and scalp.

All cases of Lyme disease, whether clinically diagnosed or laboratory confirmed, are reportable to local public health under the Health Protection and Promotion Act. Note: This includes individuals who have been clinically diagnosed with Lyme disease in the absence of serology. Public Health is mandated to collect information on clinical signs and symptoms (such as diameter of any erythema migrans), as well as information on tick exposure.

For Provincial surveillance case definition and disease-specific direction for the public health management of Lyme Disease, please see the Ontario Ministry of Health's Appendix 1 - Case Definitions and Disease Specific Information.

For details on how to report, please see the Reporting Requirements section.

Health Care Provider Lyme Disease Reporting Form [PDF 170 KB]

Information for the public can be found on the Lyme Disease page (Printable PDF) and Health Canada.

General Information on Lyme Disease

• Lyme Disease Position Statement and Resources, AMMI Canada (Association of Medical Microbiology and Infectious Disease Canada) eTick electronic tick identification platform, Bishop’s University
• Lyme Disease Resources, Health Canada
• Ontario Lyme Disease Map – Estimated Risk Areas, Public Health Ontario (For the most current map, at Lyme disease | Public Health Ontario, under “Type of Resource” click on “Surveillance Report” and look for most current year)
• For Health Professionals: Lyme Disease, Health Canada 
• Clinical Guidance Document: Management of Tick Bites and Investigation of Early Localized Lyme Disease (September 2023), Ontario Health (under Guidance Documents, please see “Clinical Guidance” section under "Lyme Disease" heading), Health Quality Ontario (HQO)
• Human Tick-borne Disease in Ottawa [PDF - 695 KB], Ottawa Public Health
• Lyme Disease Resources, Public Health Ontario
• Summary: Ticks Species in Ontario (in English only), Public Health Ontario: This report brings together the scientific literature and surveillance information on ticks of Ontario into a single source.  Explore the tick species reported from Ontario in the last 120 years, with information on their distribution, establishment status and medical and veterinary importance. 
• Ontario Public Health Standards: Requirements for Programs, Services and Accountability Infectious Disease Protocol - Appendix 1: Case Definitions and Disease Specific Information: Lyme Disease, Ontario Ministry of Health.
• Surveillance for Ixodes scapularis and Ixodes pacificus ticks and their associated pathogens in Canada, 2020, Canada Communicable Disease Report (CCDR)

Reporting

• Health Care Provider Lyme Disease Reporting Form [PDF 170 KB], Ottawa Public Health

Lab Testing

• Lyme Disease Serology, Public Health Ontario
• Tick Submission Form, Public Health Ontario will continue to accept ticks for identification from members of the public through health care providers. Ottawa Public Health does not accept ticks for identification. 

International Resources on Lyme Disease

• Lyme Disease Resources, U.S. Centers for Disease Control and Prevention

• Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis and Treatment of Lyme Disease Published CID, 11/30/2020
• M. Mora et al., Shorter versus longer duration of antimicrobial therapy for early Lyme disease: A systematic review and meta-analysis, Diagnostic Microbiology and Infectious Disease 109, no. 2 (June 2024). ScienceDirect.
  
• TickEncounter Resource Center, University of Rhode Island