Lyme Disease Serologic Testing Interval
If initial serologic testing is negative in a patient with suspected Lyme disease and symptoms for less than 4 weeks, repeat testing should be performed 2-4 weeks after symptom onset to allow for antibody development. 1
Testing Algorithm Based on Symptom Duration
Early Disease (< 4 weeks of symptoms)
- Initial testing may be falsely negative due to delayed antibody response, as antibodies are often not detectable in the primary stage of infection using currently available test methods 1
- Serologic testing is negative in many patients during the initial 3 weeks after infection 2
- Perform both IgM and IgG Western blot during the first 4 weeks of illness if the initial EIA/ELISA is positive 1
- Repeat testing 2-4 weeks after symptom onset if initial testing is negative but clinical suspicion remains high 1
Late Disease (> 4 weeks of symptoms)
- Only IgG Western blot should be performed after 1 month of symptoms 1
- IgM Western blot is not interpretable after 1 month's duration because the likelihood of false-positive results for current infection is high 1
- Patients with early disseminated or late-stage disease usually have strong serologic reactivity 1
Critical Timing Considerations
Antibody Development Timeline
- Specific antibodies develop approximately 2 weeks after symptom onset 1
- Antibodies reach maximum titers after 3-4 weeks from onset of clinical manifestations 1
- IgG antibodies are frequently present in the second stage of disease 1
- Patients with stage III illness typically have high IgG titers 1
Common Pitfalls to Avoid
Do not test too early: Testing before antibody development leads to false-negative results and unnecessary repeat testing 2, 3
Do not use IgM after 4 weeks: IgM Western blot results after 1 month of symptoms have high false-positive rates and should not be ordered 1
Do not confuse persistent antibodies with active infection: Antibodies persist for months to years after successful treatment and should not be used as markers of active disease 1, 4
Do not retest after treatment to assess cure: Serologic testing remains positive long after successful treatment and cannot distinguish between past and ongoing infection 4, 5
Special Clinical Scenarios
Erythema Migrans
- Clinical diagnosis alone is sufficient without laboratory confirmation in the United States 1
- Patients can be reasonably diagnosed and treated based on history and clinical signs alone 1
Neuroborreliosis
- CSF pleocytosis may be absent if only several days have elapsed since disease onset 1
- Intrathecally-produced antibodies may not be detectable for a short time after symptom onset 1
- Most cases show intrathecally produced antibodies in CSF, which is the most important microbiological diagnostic criterion 1