CXCL9 and Q fever: CXCL9 production was significantly higher in chronic Q fever patients (median 15.1 ng/mL, IQR 8.5–26.5) than in healthy controls (median 3.6 ng/mL, IQR 1.7–8.2, p < 0.05) and past Q fever patients (median 3.8 ng/mL, IQR 2.8–5.3, p < 0.05).