Diagnosis
Diagnosis Is Primarily Clinical
Lyme disease is diagnosed primarily based on your symptoms, potential exposure history, and physical examination — not laboratory tests alone. Standard blood tests have significant limitations, especially in the first weeks of infection. A clinician experienced in tick-borne illness takes a comprehensive approach that considers your symptom timeline, geographic context, and outdoor activities.
The CDC Two-Tier Testing Protocol
The standard laboratory approach uses a two-step process:
ELISA / EIA Screening Test
An enzyme-linked immunosorbent assay (ELISA) detects antibodies your immune system produces in response to Borrelia bacteria. This test is highly sensitive but produces false positives. A positive or indeterminate result triggers the second test.
Western Blot Confirmatory Test
The Western blot identifies specific antibody bands associated with Lyme infection, providing greater specificity. A positive result requires certain defined bands to be present.
Why Tests Miss Early Lyme Disease
Antibody tests detect your immune response — not the bacteria itself. In the first 2–3 weeks of infection, your body may not have produced enough antibodies for the test to detect. A negative result during this window does not rule out Lyme disease. If symptoms are consistent and exposure occurred, many clinicians begin treatment before test results return.
When the Rash Confirms Diagnosis
If the characteristic erythema migrans rash is present, that alone is sufficient to diagnose Lyme disease — no laboratory test is required. This is why recognizing the rash and seeking prompt medical care is so important.
Preparing for Your Appointment
The more information you bring, the better equipped your provider will be to make an accurate assessment. Document:
- Any known tick bites, including date and location on body
- Dates and locations of any recent outdoor activities in wooded or grassy areas
- When your symptoms started and how they have progressed
- All symptoms, even those that seem unrelated
- Current medications and recent health history
Use our Symptom Journal & Visit Prep to organize this information before your visit.
Questions to Ask Your Doctor
- Do my symptoms and exposure history suggest Lyme disease?
- Should treatment begin while we wait for test results?
- Should I also be tested for tick-borne co-infections?
- If my test is negative but symptoms continue, when should we retest?
- Would you refer me to an infectious disease specialist?