Risk of haematologic cancers among individuals tested for Borrelia burgdorferi antibodies, and Borrelia burgdorferi seropositive individuals: a nationwide population-based matched cohort study

Clin Microbiol Infect. 2024 Feb;30(2):231-239. doi: 10.1016/j.cmi.2023.10.017. Epub 2023 Oct 21.


Objectives: In a nationwide, matched cohort study, we aimed to investigate risks of haematologic cancers among individuals tested for Borrelia burgdorferi (Bb) antibodies, and among serum Bb seropositive individuals.

Methods: We identified all Bb seropositive individuals in Denmark (1993-2020) (n = 52 200) and constructed two age- and sex-matched comparison cohorts: (a) Bb seronegative controls (n = 104 400) and (b) background population controls (n = 261 000). We calculated short-term OR (aOR) (<1 month of study inclusion), and long-term hazard ratios (aHR) (>1 month after study inclusion) adjusted for age and sex. We stratified seropositive individuals on only Bb-IgM seropositive (n = 26 103), only Bb-IgG seropositive (n = 18 698), and Bb-IgM-and-IgG seropositive (n = 7399).

Results: Compared with the background population, individuals tested for Bb antibodies had increased short-term (aOR: 12.6, 95% CI: 10.1-15.6) and long-term (aHR: 1.3, 95% CI: 1.2-1.4) risk of haematologic cancers. The Bb seropositive individuals had no increased risk of haematologic cancers compared with those who tested negative for Bb, except that Bb-IgM-and-IgG seropositive individuals had increased long-term risk of chronic lymphatic leukaemia (aHR: 2.0, 95% CI: 1.2-3.4).

Discussion: Our results suggest that Bb antibody testing is included in the work-up of unspecific symptoms preceding diagnosis of haematologic cancers. Bb-IgM-and-IgG seropositivity was associated with a two-fold increased long-term risk of chronic lymphatic leukaemia, which warrants further investigation.

Keywords: Borrelia burgdorferi sensu lato; Borreliosis; Cohort study; Haematologic cancer; Leukaemia; Lyme disease; Serology.

MeSH terms

  • Antibodies, Bacterial
  • Borrelia burgdorferi Group*
  • Borrelia burgdorferi*
  • Cohort Studies
  • Hematologic Neoplasms* / epidemiology
  • Humans
  • Immunoglobulin G
  • Immunoglobulin M
  • Leukemia, Lymphocytic, Chronic, B-Cell*
  • Lyme Disease* / diagnosis
  • Lyme Disease* / epidemiology
  • Lyme Disease* / microbiology


  • Antibodies, Bacterial
  • Immunoglobulin G
  • Immunoglobulin M