CD40LG and tick-borne infectious disease: Among 1350 patients suspected of a tick-borne infection between 2000 and 2009, 418 (31%) of patients were found positive for either IgG or IgM antibodies, using IFA against A. phagocytophilum, for both IgG and IgM antibody (cut-off value 1:64 and 1:20, respectively) [96].