Borrelia infection and risk of non-Hodgkin lymphoma.

Reports of the presence of Borrelia burgdorferi DNA in malignant lymphomas have raised the hypothesis that infection with B. burgdorferi may be causally related to non-Hodgkin lymphoma (NHL) development. We conducted a Danish-Swedish case-control study including 3055 NHL patients and 3187 population controls. History of tick bite or Borrelia infection was ascertained through structured telephone interviews and through enzyme-linked immunosorbent assay serum analyses for antibodies against B. burgdorferi in a subset of 1579 patients and 1358 controls. Statistical associations with risk of NHL, including histologic subtypes, were assessed by logistic regression. Overall risk of NHL was not associated with self-reported history of tick bite (odds ratio [OR] = 1.0; 95% confidence interval: 0.9-1.1), Borrelia infection (OR = 1.3 [0.96-1.8]) or the presence of anti-Borrelia antibodies (OR = 1.3 [0.9-2.0]). However, in analyses of NHL subtypes, self-reported history of B. burgdorferi infection (OR = 2.5 [1.2-5.1]) and seropositivity for anti-Borrelia antibodies (OR = 3.6 [1.8-7.4]) were both associated with risk of mantle cell lymphoma. Notably, this specific association was also observed in persons who did not recall Borrelia infection yet tested positive for anti-Borrelia antibodies (OR = 4.2 [2.0-8.9]). Our observations suggest a previously unreported association between B. burgdorferi infection and risk of mantle cell lymphoma.