Laboratory diagnosis of Lyme disease remains one of the most complex areas among infections. In clinical practice, the most commonly used serological tests measure the immune system’s response, primarily through the detection of IgM and IgG antibodies.
However, scientific literature emphasizes that the interpretation of these results is not always straightforward.
What Does IgM Mean in Lyme Disease Diagnostics?
IgM antibodies typically appear during the early stage of infection. In the standard two-tier diagnostic system (ELISA + Western blot), IgM testing may have particular relevance when early infection is suspected.
However, according to the Cleveland Clinic Journal of Medicine review article, interpretation of IgM results requires increased clinical caution.
The article highlights that:
- during early infection, the immune response may not yet be measurable,
- positive IgM results can be difficult to interpret in patients with long-standing symptoms, in many cases they coincide with an ongoing infection
- cross-reactivity and false-positive results may occur in certain situations,
- laboratory findings alone are not sufficient to establish a diagnosis.
The authors emphasize that IgM and IgG results should always be interpreted together with:
- clinical symptoms,
- medical history,
- tick exposure,
- and the duration of symptoms.
Why Is Antibody-Based Testing Challenging?
Serological tests fundamentally assess the immune system’s response rather than directly detecting the pathogen itself.
This means that:
- in the early phase of infection, antibody production may still be insufficient,
- the immune response from a previous infection may persist for an extended period,
- and non-specific immune reactions may influence the results in some cases.
For this reason, increasing attention is being directed toward diagnostic approaches that are not based on measuring the immune response.
Direct Diagnostic Approach: How Is DualDur® Different?
The DualDur® test operates on a different principle than traditional IgM/IgG serological testing.
While antibody-based methods evaluate the immune response, DualDur® is a direct diagnostic method that identifies live and motile Borrelia bacteria directly in the blood sample.
This approach:
- is not based on antibody response measurement,
- does not evaluate IgM or IgG values,
- but instead focuses on the direct presence of the pathogen.
The goal of direct diagnostic methods is to support clinical evaluation from a different perspective, particularly in cases where the interpretation of serological findings and symptoms is not entirely clear.
Diagnostics Always Require Complex Clinical Decision-Making
The diagnosis of Lyme disease should not rely solely on a single laboratory test. According to international professional recommendations, diagnostic decisions should always take into consideration:
- clinical presentation,
- the temporal course of infection,
- possible tick exposure,
- and the overall context of laboratory findings.
For this reason, an accurate diagnostic approach may be especially important in complex or uncertain clinical cases.
