Lyme disease in humans is caused by three species of Borrelia bacteria. In North America, Lyme disease is caused primarily by Borrelia burgdorferi, while in Europe the disease is caused mainly by B. garnii and B. afzelli. In Ontario, transmission occurs through the bite of infected blacklegged ticks called Ixodes Scapularis or deer ticks.
The overall risk of acquiring Lyme disease in Toronto is low but is increased if doing activities in wooded and bushy areas in eastern parts of Toronto.
Blood sample should be collected in a red-top tube and sent to Public Health Ontario Laboratory.
The first step involves testing using a screening Enzyme Immunoassay (EIA) test.
If initial EIA result is non-reactive, healthcare providers should consider an alternative diagnosis; or in cases where the patient has had symptoms for less than or equal to 30 days, the provider may treat the patient and follow up with a convalescent serum.
If the EIA result is reactive or indeterminate, a confirmatory test using Western Immunoblot assay is performed.
Blood tests may be negative in patients with early-stage Lyme disease or in patients previously treated with antibiotics.
The accuracy of blood tests increases as the infection progresses, although it is recognized that a small proportion of patients with later-stage Lyme disease may test negative.
The stage of infection and the possible impact of treatment on the outcomes of blood testing should be taken into consideration during diagnosis.
If a patient was exposed to other species of Borrelia such as those that occur in Europe:
Provide travel history and request testing for European Lyme disease.
The specimens from these patients are sent to the National Microbiology Laboratory for antibody testing.
Ticks must be collected in a clean transparent container. Name of the patient and date of birth must be marked on the container. A sterile urine collection container may be used for this purpose.
All ticks submitted for testing must be accompanied by the Surveillance Form for Tick Identification (Public Health Ontario)
Ticks must be couriered or delivered to:
Parasitology Laboratory, Public Health Ontario
MaRS 2 Tower (south side)
661 University Avenue
Toronto, Ontario M5G 1M1
To assist with Toronto Public Health’s (TPH) passive surveillance activities, please remember to fax the submission form to 416-392-0714, attention Vector Borne Disease Manager or call TPH for tick submission assistance at 416-338-7600.
Note: The City of Toronto has a prevalence of ticks infected with Borrelia burgdorferi greater than 20 per cent and therefore meets the criteria for consideration of post-exposure prophylaxis.
A single dose of oral doxycycline may be offered to patients of any age when all of the following conditions are met:
Adult or nymph of I. scapularis tick was attached for more than 24 hours; and
Prophylaxis can be started within 72 hours from the time that the tick was removed: and
Person was exposed in an area where ecologic information indicates that the rate of infection of ticks is greater than 20 per cent. This applies to the City of Toronto, and
Doxycycline treatment is not contraindicated
There is effective antibiotic treatment for early localized Lyme disease. Should prophylaxis not be indicated based on the above criteria, the health care provider should watch for signs and symptoms of Lyme disease and treat early.