Background: Lyme disease is widespread throughout the world, including Latvia. On average period 2009 to 2018, there have been 613 cases of Lyme disease registered in Latvia every year according to data from the Center for Disease Prevention and Control. Mainly early skin manifestations such as erythema migrans and neurological manifestations such as meningitis, cranial neuropathy and motor or sensor radiculoneuropathy of this disease are being discussed and emphasized. Therefore, undiagnosed and unexamined often remain articular manifestations of Lyme disease, leading to prolonged treatment and reduced patient quality of life.

Objectives: To investigate clinical presentation, immunological changes, and response to therapy in patients with Lyme disease.

Methods: A retrospective single center study was performed in the outpatient clinic Orto (Riga, Latvia) in the period from January 2018 until December 2021. Medical records from patients with diagnosed Lyme disease and articular symptoms, based on epidemiological, clinical and immunological findings, were analyzed. Patients who had other types of arthropathies were excluded.

Results: In total 76 patients were included in the study (54 females, 22 males, age range 19-84 years, median age 48.5 years), of whom 48 patients had arthritis and 28 arthralgias. Out of all patients with arthritis - 25 had monoarthritis, 16 - had oligoarthritis and 7 had polyarthritis. At the first visit patients with arthralgia had a median IgM 28.2 Au/ml (IQR 15.27- 47.35) and IgG 25.00 Au/ml (IQR 5.00 – 142.30) and patients with arthritis had a median IgM 14.7 Au/ml (IQR 5.50 - 28.80) and IgG 142.7 Au/ml (IQR 82.32-237). After the treatment with Doxycycline 200 mg QD for 30 days, 52 patients came to the 2nd visit, of them 41 patients with improvement of symptoms and 11 without. More improvement was seen in the arthritis group. After treatment the median IgM in arthralgia/ arthritis groups was 22.5 Au/ml (IQR 8.72-38.82) / 13.8 Au/ml (IQR 6.03-24.15) and IgG was 42.4 Au/ml (IQR 8.15 – 90.60) / 106.7 Au/ml (IQR 23.57-203.95). In both groups with arthralgias or arthritis, patients who had a positive clinical response after treatment had a significantly lower post-treatment IgG than before treatment (p <0.05, Wilcoxson signed rank test). At the same time patients who did not respond to the treatment had no significant difference between pre- and post- treatment IgG antibodies (p> 0.05, Wilcoxson signed rank test).

Conclusion: In all patients with musculoskeletal complaints the possibility of Lyme disease should be evaluated. The decrease of antibody titers may indicate a positive prognosis in patients with musculoskeletal manifestations of Lyme disease.

Disclosure of Interests: None declared