Among the seropositive group, pooled seroprevalence of IgG antibody was 10.2 %, while pooled seroprevalence of IgM antibody was 1.5 %, indicating recent or acute infection (Table 2, Part A).1.2Seroprevalence of Q fever was statistically different in subgroups of countries based on income categories (P = 0.02), and seroprevalence in low/lower-middle income countries (24.4 %, 9 % CI: 0.0–56.4) was higher than in upper-middle-income (16.4 %, 95 % CI: 7.1–25.7) and high-income (9.0 %, 95 % CI: 6.5–11.5) (Fig. 2). Here, CD40LG is linked to Q fever.