Antibodies and T-cell reactivity to Borrelia burgdorferi in an asymptomatic population: a study of healthy blood donors in an inland town district in the south-east of Sweden.

To address the issue of whether Borrelia infection can be asymptomatic, blood donors with no history of borreliosis (n = 408) were screened for antibodies against Borrelia burgdorferi. Seropositive individuals (n = 17) were further investigated with respect to Borrelia-specific T-cell reactivity, using an interferon-gamma ELISPOT assay. Anti-Borrelia antibodies as well as Borrelia-specific T-cell responses were evident in 9 asymptomatic donors, strongly supporting a current or previous asymptomatic Borrelia infection.