The 2026 ILADS conference once again highlighted that the diagnosis of Lyme borreliosis continues to raise a number of unresolved issues – particularly regarding the interpretation of the immune response.
At the London event, Dr Klára Esztó and Dr András Pál Bózsik analysed the data together, with Dr Esztó presenting the clinical cases. In the majority of these cases, the use of the DualDur direct testing method successfully identified Borrelia and Bartonella infections in patients who had suffered multiple spontaneous miscarriages. Following specific treatment, 13 healthy babies were born out of the 16 cases. The case studies generated significant professional interest and sparked lively discussion among the participants.
Clinical cases and interpretative challenges
The audience raised numerous questions regarding the cases presented. One of the greatest challenges in Lyme disease diagnosis is that the attending physician often fails to investigate the connections between the frequently mild, barely noticeable symptoms, and thus does not request Lyme testing. And if a laboratory test is requested, it is typically a serological test, which the physician may not necessarily be able to interpret correctly. In the present cases, the obstetrician-gynaecologist referred the patients to a Lyme disease specialist, for whom the laboratory findings and the clinical picture were perfectly consistent, and the specific, combined treatment resulted in recovery. The latter also confirmed the correctness of the diagnosis (so-called ex juvantibus diagnosis).
The main takeaways from the presentation were that infertility or habitual spontaneous abortion, on its own or alongside other mild Lyme symptoms, can be a characteristic leading symptom of Lyme disease and bartonellosis. Furthermore, in every case where an IgM test was performed, the result was a true positive, as confirmed by direct testing.
The issue of IgM persistence
One of the central topics of the professional debate was why, in certain cases, the IgM response persists whilst IgG does not appear.
It is a known phenomenon that Borrelia can influence the functioning of the immune system and may inhibit IgM–IgG isotype switching. This may partly explain why the IgG response is absent in some patients.
However, one question remains open:
why does the IgM response persist, despite the fact that it is normally short-lived?
According to immunological principles, IgM antibodies typically degrade within 10–12 days. However, the mechanism underlying their persistent presence is not fully understood.
The role of Borrelia’s variability
One possible explanation raised at the conference was the extraordinary genetic and antigenic variability of Borrelia. This was not only predicted by Dr Béla Pál Bózsik’s research decades ago, but is now supported by most scientific articles. The former president of ILADS, who was part of the team that developed the first PCR test, commented on this during the discussion: “the most variable pathogen I have ever seen”.
The pathogen:
- constantly changes its surface antigens
- adapts at a genetic level
- successive generations can differ significantly from one another
In his presentation, András Pál Bózsik explained that this dynamic may result in the immune system repeatedly perceiving the pathogen as a ‘new infection’ and triggering an IgM response time and again.
The presumed cyclical pattern (in 3–4-week cycles) may explain the development of recurrent IgM responses – which therefore do not represent the persistence of the IgM reaction, but rather the triggering of new reactions. There is, however, general agreement among laboratory specialists that the serological tests currently in use are highly specific, so the likelihood of cross-reaction with other pathogens is low. This supports the view that the IgM response measurable in the late stage also yields a true positive result.
This serological pattern was identified on the basis of more than one hundred thousand serological tests carried out at the National Institute of Public Health under the leadership of Dr Béla Pál Bózsik, where virtually every course of the disease could be modelled. The typical course, which involves an IgM response developing over 4–6 weeks followed by a slowly developing IgG response, is not observed in the majority of cases.
The role of direct detection methods
In connection with the cases presented, direct diagnostic approaches have also come to the fore.
The DualDur Lyme test is an assay that does not measure the immune response but aims to directly detect the presence of the pathogen. This may be particularly relevant in clinical situations where serological results do not provide a clear answer.
The method has been validated at European level and aims to provide supplementary, clinically meaningful information to aid diagnostic decisions.
International interest and a changing landscape
The interest shown at the conference was significant at an international level as well. The DualDur stand, which was also present as an exhibitor, was visited by American specialists and representatives of the ILADS leadership.
In the United States, there is an increasing emphasis on the more accurate diagnosis of Lyme disease, which is also reflected in changes to the regulatory environment. This trend is expected to influence the development of diagnostic approaches.
Further professional connections
The insights from the conference also relate to several other relevant topics, such as the impact on patients’ quality of life:
https://lymenet.hu/2026/04/17/kirstie-haysman-amikor-a-lyme-kor-teljesen-megvaltoztatja-az-eletet-3/
András Bózsik’s professional profile:
https://membercompass.ilads.org/contacts/andras-bozsik
Previous ILADS report:
https://dualdur.com/2026/03/27/ilads-dualdur/
Summary
One of the key takeaways from the 2026 ILADS conference is that Lyme diagnosis still cannot be reduced to a single method or answer.
In clinical decision-making, an increasingly important role is played by:
- interpreting the dynamics of the immune response
- taking into account the biological characteristics of the pathogen
- and the combination of different diagnostic approaches
The issue of IgM persistence clearly demonstrates that even in the case of immunological patterns once thought to be fundamental, further research and clinical experience are required.
