Lyme disease serology (two-tier, via Public Health Ontario)

Pick Ordered or Not ordered to see the note.

Indicated when

• —A compatible exposure history (tick bite, or travel to or residence in an area with Lyme-endemic or emerging-risk ticks) together with symptoms consistent with disseminated or late Lyme disease (e.g. Lyme arthritis, facial palsy or other neurologic findings, carditis), when there is no erythema migrans rash to diagnose clinically [1, 3]
• —Classic early erythema migrans rash with a compatible exposure history is a clinical diagnosis and does not require serology before starting treatment [1]

Not indicated when

• —No exposure history (no tick bite, no travel to or residence in a Lyme risk area) and no clinical presentation compatible with Lyme disease [3]
• —As a routine explanation for fatigue, general malaise, or nonspecific symptoms without a compatible exposure history or clinical picture

Why not

Serology performed outside a compatible exposure history and clinical picture has a meaningful chance of being a false lead: antibody tests can remain positive for years after past exposure, and interpreting Western blot/immunoblot results requires validated criteria. The CDC has specifically cautioned that some laboratories 'interpret Western blots using criteria that have not been validated and published in peer-reviewed scientific literature' [4]. Testing without a plausible history mostly generates anxiety and further work-up rather than a clinically actionable result [3].

Better first step

Take an exposure history (tick bite, time spent in or travel to a Lyme risk area) and look for a compatible clinical picture. Diagnose classic early erythema migrans clinically, without serology, in a patient with a compatible exposure. Reserve two-tier serology, via Public Health Ontario, for suspected disseminated or late Lyme disease without a diagnostic rash, using validated testing algorithms rather than send-out tests from unvalidated private laboratories [5, 2].

Typical ND rationale

An ND may order or recommend Lyme serology in a patient with fatigue, joint pain, or other chronic nonspecific symptoms, reasoning that Lyme disease is underdiagnosed, standard testing can miss it, and ruling it in or out is worthwhile given how treatable early disease is.

Ontario coverage & CONO orderability

OHIP status

unverified

Lyme serology does not appear by name in the community 2026 Schedule of Benefits for Laboratory Services searched this session; it is performed by Public Health Ontario as a public health laboratory service rather than billed through the community Schedule [2]. PHO's test information page describes specimen and requisition requirements but does not state a fee or confirm the test is provided to the patient at no charge, so whether an OHIP-insured physician's order carries any cost to the patient could not be confirmed this session; marked unverified rather than assumed, consistent with docs/research/ontario-coverage.md's guidance for tests outside the community Schedule. ND-ordered Lyme serology, through PHO or otherwise, is patient-paid regardless [6].

CONO orderable

Yes — CONO list #90

CONO list item 90, 'Lyme Disease Antibodies', blood specimen; the parsed CONO list entry directs use of a specific (PHO) requisition. This record covers that validated PHO two-tier pathway; the unvalidated protocols offered by private laboratories such as IGeneX or Armin Labs are addressed in the separate Lyme disease testing via private, non-PHO laboratories (IGeneX, Armin Labs, and similar) record, which is not on the CONO list.

Linked conditions

• Lyme disease ↗
• tired ↗

Counselling script

“If you've had a tick bite or spent time in a Lyme risk area and you have symptoms that fit with Lyme disease, especially without the classic rash, this test through the public health lab is the right next step. Without a real chance of tick exposure, I wouldn't order it for fatigue or vague symptoms alone, since a positive result in that situation is more likely to be misleading than helpful. If a compatible exposure or new symptoms come up, we can revisit this.”

Revisit if

• —A tick bite or travel/residence in a Lyme risk area is identified
• —Erythema migrans rash, joint swelling, facial palsy, or other findings compatible with Lyme disease develop

References

1. [1]Public Health Agency of Canada (2026). Lyme disease: For health professionals. linkDiagnosis of early localized Lyme disease is primarily clinical; in the absence of an erythema migrans rash, laboratory testing is recommended
2. [2]Public Health Ontario (2026). Lyme Disease - Serology: Test Information Index. linkPHO performs Lyme serology using a modified two-tier testing algorithm
3. [3]Canadian Rheumatology Association (Pediatric Rheumatology) / Choosing Wisely Canada (2025). Recommendations: Pediatric Rheumatology. linkCRA: do not order Lyme serology without an exposure history or endemic-area residence and a characteristic clinical presentation
4. [4]US Centers for Disease Control and Prevention (MMWR) (2005). Notice to Readers: Caution Regarding Testing for Lyme Disease. linkolder guidelineSome laboratories interpret Western blots using criteria not validated in peer-reviewed literature
5. [5]US Centers for Disease Control and Prevention (2026). Testing and Diagnosis for Lyme disease. linkCDC recommends FDA-cleared antibody tests for laboratory diagnosis of Lyme disease
6. [6]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkTests ordered by anyone other than an authorized provider, including NDs, are not insured services