Question

. Borreliosis is primarily detected using two step serology. What are the components of each step? What are the limitations of diagnosis associated with each step? (

Answer 1

Answer:

1. The appearance of a typical EM rash occurring in season and with a history of exposure to ticks should be considered an indication for antibiotic treatment, irrespective of the results of serological testing.

2. An EM-like rash occurring out of season and/or after exposition in a Lyme nonendemic area where ticks are not known to be established should be investigated with antibody testing.

   1. Initial negative serological tests in patients with skin lesions suggestive of EM should have testing repeated after four weeks.

3. Patients with symptoms and signs suggestive of early disseminated or late Lyme disease should be tested for antibodies to B burgdorferi.

   1. Initial testing should include an EIA commercially available and approved for use in Canada.

   2. Sera that are positive or indeterminate by an EIA should be subjected to Western blot confirmatory testing.

   3. Sera that are screened negative for antibodies using an EIA should not be subjected to Western blot testing.

4. Western blot tests should be interpreted using criteria set forth by the CDC Working Group.

   1. Western blot tests that fail to meet all of the criteria set out by the CDC Working Group should be reported as negative; testing may be repeated when it is appropriate to do so.

   2. The specific banding patterns seen on Western blots should not be reported.

   3. When serological testing is requested for Lyme borreliosis, and when the initial screening test is positive and the subsequent Western blot confirmatory test is negative, specimens should be reported as ‘negative for antibodies to B burgdorferi’.

5. Culturing for B burgdorferi is a low-yield procedure and is not encouraged; if performed, it should be done only on biopsies from EM lesions and synovial or spinal fluid.

6. There is inadequate evidence to support the use of B burgdorferiantigen testing as an adjunct to the diagnosis of Lyme borreliosis.

   1. The role of NAT (eg, PCR) is limited, and its use should be restricted to patients with objective evidence of joint or central nervous system infection.

   2. There is inadequate evidence to recommend PCR testing of blood and urine for the diagnosis of Lyme disease.

7. Patients without objective findings suggestive of B burgdorferi infection should not be ‘screened’ for B burgdorferiantibodies.

   1. The diagnosis of Lyme borreliosis should not be based on positive serological tests in the absence of objective findings of infection and a credible epidemiological link to infected ticks.

   2. Bypass of laboratories that apply the two-step testing procedure (initial EIA followed by Western blot testing) is strongly discouraged.

   3. Patients should be made aware that antibody testing is subject to false-positive results, and that a positive test in the absence of objective findings and credible exposure histories usually represent false-positive results.

8. The role of antibody testing to monitor the results of therapy has not been established and is therefore not recommended.

9. The role of the microbiology laboratory in the assessment of patients with the persistence of symptoms following antibiotic treatment has not yet been established.

10. In patients in whom tick exposure occur outside of North America, physicians should seek diagnostic advice on testing from a Canadian laboratory with expertise in the diagnosis of Lyme disease.

11. Testing patients suspected of Lyme disease for other tick-associated diseases should not be routinely performed; instead, testing should be based on risk exposure and clinical symptoms.