Lyme Borreliosis

Lyme borreliosis diagnosis currently relies on clinical assessment and detection of Borrelia-specific antibodies. However, serology does not allow reliable assessment of active infection. Evaluation of the cellular immune response through Borrelia-specific T lymphocyte monitoring may provide complementary diagnostic and prognostic information. This study aims to assess Borrelia afzelii-specific T-cell responses using multiparameter flow cytometry after stimulation with standardized peptide pools. This approach enables the characterization of CD4+ and CD8+ T cells, including polyfunctional immune responses. The diagnostic and prognostic value of this immunomonitoring strategy will be evaluated in patients with acrodermatitis chronica atrophicans, a late manifestation of Lyme borreliosis associated with B. afzelii.

Lyme borreliosis, commonly known as Lyme disease, has been clinically described for more than a century, but has been officially recognized for 40 years, with the detection of the Borrelia bacterium by W. Burgdorfer, in ticks of the Ixodes ricinus complex, identified a few years before.

Ticks are blood-sucking arthropods that feed on vertebrate hosts. Although wild and domestic animals are the primary source of tick blood meals, humans can be an accidental host. During a blood meal, a microorganism can be transmitted to the host who can develop a disease. All infectious diseases transmitted by ticks are referred to as tick-borne diseases (TBDs). They are the most prevalent vector-borne diseases in the Northern Hemisphere. Among these diseases, Lyme borreliosis is the most common. In Europe, Lyme borreliosis does not cause high fevers (\> 38°C). Therefore, when a patient presents with a high fever with the notion of exposure to ticks, another etiology must be suspected. Anaplasma phagocytophilum and the tick-borne encephalitis virus are classically described as causing febrile syndromes. In France, ticks and tick-borne diseases are increasing, particularly those associated with the Ixodes ricinus tick. This tick is mainly present in forest ecosystems with a peak of activity in May. Foresters represent a population with biting ticks and tick-borne diseases, notably Lyme borreliosis.