Seroprevalence of Borrelia burgdorferi Antibodies in Patients with Ulcerative Colitis and Its Association with Disease Activity.

Background and Aim: Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by immune dysregulation. Environmental factors, including infectious agents, have been proposed to influence disease activity in inflammatory bowel disease. Although Borrelia burgdorferi has been shown to exert complex immunomodulatory effects on host immune responses, its seroprevalence and potential association with disease activity in patients with ulcerative colitis have not been systematically investigated. This study aimed to evaluate the seroprevalence of Borrelia burgdorferi IgG antibodies in patients with ulcerative colitis and to assess the relationship between seropositivity and laboratory markers of disease activity.

Methods

In this retrospective observational study, 100 patients with ulcerative colitis (59 males, 41 females; mean age 48.5 ± 17 years) who underwent Borrelia burgdorferi IgG serological testing due to musculoskeletal or neurological symptoms suggestive of possible Lyme disease between October 2020 and October 2024 were included. Demographic characteristics, hematological and biochemical parameters, and inflammatory markers were compared between seropositive and seronegative groups. Due to the retrospective design, validated clinical disease activity indices were not consistently available; therefore, disease activity was indirectly assessed using laboratory inflammatory markers.

Results

Among patients with ulcerative colitis, 22% were seropositive for Borrelia burgdorferi IgG. Seropositive patients had significantly lower uric acid, alkaline phosphatase, and C-reactive protein levels compared to seronegative patients (p = 0.001, p = 0.023, and p = 0.020, respectively). Free T4 levels were significantly higher in the seropositive group (p = 0.049). In terms of erythrocyte indices, mean corpuscular volume and mean corpuscular hemoglobin were significantly higher, while RDW-CV values were significantly lower in seropositive patients (all p < 0.05).

Conclusion

Borrelia burgdorferi IgG seropositivity in patients with ulcerative colitis was associated with lower laboratory markers of systemic inflammation and a more stable hematological profile. Although causality cannot be established, these findings may suggest a potential association between prior Borrelia exposure and a distinct inflammatory phenotype in UC; however, this relationship should be interpreted with caution. Further prospective and mechanistic studies are warranted to clarify the potential immunological interactions between environmental microbial exposure and inflammatory bowel disease activity.