We also include in the study two control groups of sera: (i) sera from Q-fever-seropositive patients, whose seropositivity was determined using a commercially available assay (Coxiella burnetii ELISA kits; Vircell, Spain), and (ii) serum from healthy persons who were seronegative for ARF IgG/IgM and Q fever IgG/IgM, with the fact being determined via commercially available assays from Vircell, Spain. Here, CD40LG is linked to Q fever.