ARCHIVED - Lyme Disease


Please visit the current Lyme disease case definition for the latest updates.

Nationally notifiable since 2009

1.0 National Notification

Confirmed and probable cases of disease should be notified.

2.0 Type of Surveillance

Routine case-by-case notification to the federal level

3.0 Case Classification

3.1 Confirmed case

Clinical evidence of illness with laboratory confirmation:

  • isolation of Borrelia burgdorferi from an appropriate clinical specimen
  • detection of B. burgdorferi DNA by PCR

Clinical evidence of illness with a history of residence in, or visit to, an endemic area and with laboratory evidence of infection:

  • positive serologic test using the two-tier ELISA and Western Blot criteria (see section 4.0)

3.2 Probable case

Clinical evidence of illness without a history of residence in, or visit to, an endemic area* and with laboratory evidence of infection:

  • positive serologic test using the two-tier ELISA and Western Blot criteria (see section 4.0)

Clinician-observed erythema migrans without laboratory evidence but with history of residence in, or visit to, an endemic area*

4.0 Laboratory Comments

Criteria for serologic testing are described by the guidelines of the Canadian Public Health Laboratory Network(1). Serologic evidence is confirmatory only in patients with erythema migrans or objective clinical evidence of disseminated Lyme disease, and a history of residence in, or visit to, an endemic area.

5.0 Clinical Evidence

The clinical information presented below is not intended to describe the complete range of signs and symptoms that may be used in a clinical diagnosis of Lyme disease. Symptoms of early or late disseminated Lyme disease are described in the 2006 clinical practice guidelines of the Infectious Diseases Society of America(2). Other symptoms that are, or have been suggested to be, associated with Lyme disease (including those of so-called "chronic" Lyme disease and post Lyme disease syndromes) are considered too non-specific to define cases for surveillance purposes, whether or not they may be caused by B. burgdorferi infection. The following signs and symptoms constitute objective clinical evidence of illness for surveillance purposes for Lyme disease:

Erythema migrans: a round or oval expanding erythematous area of the skin greater than 5 cm in diameter and enlarging slowly over a period of several days to weeks. It appears one to two weeks (range 3-30 days) after infection and persists for up to eight weeks. Some lesions are homogeneously erythematous, whereas others have prominent central clearing or a distinctive targetlike appearance. On the lower extremities, the lesion may be partially purpuric. Signs of acute or chronic inflammation are not prominent. There is usually little pain, itching, swelling, scaling, exudation or crusting, erosion or ulceration, except that some inflammation associated with the tick bite itself may be present at the very centre of the lesion. Note: An erythematous skin lesion present while a tick vector is still attached or that has developed within 48 hours of detachment is most likely a tick bite hypersensitivity reaction (i.e. a non-infectious process), rather than erythema migrans. Tick bite hypersensitivity reactions are usually < 5 cm in largest diameter, sometimes have an urticarial appearance and typically begin to disappear within 24-48 hours.


Objective evidence of disseminated Lyme disease includes any of the following when an alternative explanation is not found:

Early neurological Lyme disease: acute peripheral nervous system involvement, including radiculopathy, cranial neuropathy and mononeuropathy multiplex (multifocal involvement of anatomically unrelated nerves), and CNS involvement, including lymphocytic meningitis and, rarely, encephalomyelitis (parenchymal inflammation of brain and/ or spinal cord with focal abnormalities). Late neurologic Lyme disease may present as encephalomyelitis, peripheral neuropathy or encephalopathy.
Lyme arthritis is a monoarticular or oligoarticular form of arthritis most commonly involving the knee, but other large joints or the tempero-mandibular joint may be involved. Large effusions that are out of proportion to the pain are typical. Lyme arthritis is often intermittent if untreated, with episodes of joint infl ammation spontaneously resolving after a few weeks to a few months. Persistent swelling of the same joint for 12 months or more is not a usual presentation.
Cardiac involvement associated with Lyme disease includes intermittent atrioventricular heart block often involving the atrioventricular node (although heart block may occur at multiple levels) and sometimes associated with myopericarditis. Carditis can occur in the early stages of the disease

6.0 ICD Code(s)

6.1 ICD-10 Code(s)


Lyme Disease (Erythema chronicum migrams due to Borrelia burgdorferi)

6.2 ICD-9 Code(s)

7.0 Type of International Reporting


These are definitions for surveillance and epidemiologic purposes only, and they do not represent clinical case definitions.

9.0 References

  1. Canadian Public Health Laboratory Network. The laboratory diagnosis of Lyme borreliosis: guidelines from the Canadian Public Health Laboratory Network. Can J Infect Dis Med Microbiol 2007;18:145-8.
  2. Wormser GP, Dattwyler RJ, Shapiro ED et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis 2006; 43:1089-134.

Date of Last Revision/Review:

May 2008

* An endemic area is defined as a locality in which a reproducing population of Ixodes scapularis or I. pacificus tick vectors is known to exist, as demonstrated by molecular methods and to support transmission of B. burgdorferi at that site

Report a problem or mistake on this page
Please select all that apply:

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: